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CydandClaude Fable 5 db7745fcd0 sda4: commit the Glaze developer hard-drive dump 
Un-ignored: the dev drive is the ground truth the restoration and
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source, BT/RP live+dev game trees, VGL_LABS pod boot, scene/audio
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NET User Reference Manual (NOS Version)
Phil Karn, KA9Q
1. The NET.EXE Program
The MS-DOS executable file net.exe provides Internet (TCP/IP),
NET/ROM and AX.25 facilities. Because it has an internal multi-
tasking operating system, net.exe can act simultaneously as a
client, a server and a packet switch for all three sets of proto-
cols. That is, while a local user accesses remote services, the
system can also provide those same services to remote users while
also switching IP, NET/ROM and AX.25 packets and frames between
other client and server nodes.
The keyboard and display is used by the local operator to control
both host and gateway level functions, for which a number of com-
mands are provided.
1.1. Installation
Net.exe uses the following directory structure:
/spool
/spool/help
/spool/mail
/spool/mqueue
/spool/rqueue
/spool/news
By default, the /spool directory is placed in the root directory
of the current drive. However, a subdirectory may be specified
with the -d command-line option described below. If a subdirec-
tory is given, the alias, autoexec.net, dialer, domain.txt and
ftpusers configuration files must also be located there.
The "/spool" directory and its sub-directories are used by the
bbs, SMTP and NNTP services. The areas, forward.bbs, history,
mail.log, rewrite and signatur configuration files are located
here.
The alias, forward.bbs and rewrite files are described in the
document "maildoc", which should be found at the same location as
this file.
1.2. net [-b] [-s <sockets>] [-d <directory>] [<startup file>]
1.2.1. -b
The -b option specifies the use of BIOS for console output; the
default is to write directly to the video display buffer. Use
this option if you are running under a windowing package and have
trouble with output "bleeding through" on top of other windows.
May 28, 1991
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1.2.2. -s
The -s option specifies the size of the socket array to be allo-
cated within net.exe. This limits the number of network connec-
tions that may exist simultaneously. The default is 40.
1.2.3. -d
The -d option allows the user to specify a directory for the con-
figuration and spool files; it defaults to the root directory of
the system.
1.2.4. Startup file
After all command-line options, the name of a startup file may be
specified. If no startup file is specified, net.exe attempts to
open a file named autoexec.net in the configuration directory of
the current drive. If the file exists, it is read and executed
as though its contents were typed on the console as commands.
(See the Commands chapter.) This feature is useful for attaching
communication interfaces, configuring network addresses, and
starting the various services.
2. Console modes
The console may be in one of two modes: command mode and converse
mode. In command mode, the prompt net> is displayed and any of
the commands described in the Commands chapter may be entered.
In converse mode, keyboard input is processed according to the
current session.
Sessions come in many types, including Telnet, FTP, AX25, NETROM,
Ping, More, Hopcheck and Tip. In a Telnet, AX25, NETROM, or Tip
session, keyboard input is sent to the remote system and any out-
put from the remote system is displayed on the console. In a FTP
session, keyboard input is first examined to see if it is a known
local command; if so it is executed locally. If not, it is
"passed through" to the remote FTP server. (See the FTP Subcom-
mands chapter). In a Ping session the user may test the path to
a remote site, and in a More session, the user may examine a
local file. A Hopcheck session is used to trace the path taken by
packets to reach a specified destination. A Tip session provides
a "dumb terminal" service that bypasses all network protocols.
The keyboard also has cooked and raw states. In cooked state,
input is line-at-a-time; the user may use the line editing char-
acters ^U, ^R and backspace to erase the line, redisplay the line
and erase the last character, respectively. Hitting either
return or line feed passes the complete line up to the applica-
tion. In raw state, each character is immediately passed to the
application as it is typed.
The keyboard is always in cooked state in command mode. It is
also cooked in converse mode on an AX25, FTP or NET/ROM session.
In a Telnet session it depends on whether the remote end has
issued (and the local end has accepted) the Telnet WILL ECHO
option (see the echo command).
On the IBM-PC, the user may escape back to command mode by hit-
ting the F10 key. On other systems, the user must enter the
escape character, which is by default control-] (hex 1d, ASCII
GS). (Note that this is distinct from the ASCII character of the
May 28, 1991
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same name). The escape character can be changed (see the escape
command).
In the IBM PC version, each session (including the command
"session") has its own screen. When a new session is created,
the command display is saved in memory and the screen is cleared.
When the command escape key (usually F10) is hit, the current
session screen is saved and the command screen is restored. When
a session is resumed, its screen is restored exactly as it
appeared when it was last current.
3. Commands
This chapter describes the commands recognized in command mode,
or within a startup file such as autoexec.net. These are given
in the following notation:
command
command literal_parameter
command subcommand <parameter>
command [<optional_parameter>]
command a | b
Many commands take subcommands or parameters, which may be
optional or required. In general, if a required subcommand or
parameter is omitted, an error message will summarize the avail-
able subcommands or required parameters. (Giving a '?' in place
of the subcommand will also generate the message. This is useful
when the command word alone is a valid command.) If a command
takes an optional value parameter, issuing the command without
the parameter generally displays the current value of the vari-
able. (Exceptions to this rule are noted in the individual com-
mand descriptions.)
Two or more parameters separated by vertical bar(s) denote a
choice between the specified values. Optional parameters are
shown enclosed in [brackets], and a parameter enclosed in <angle
brackets> should be replaced with an actual value or string. For
example, the notation <hostid> denotes an actual host or gateway,
which may be specified in one of two ways: as a numeric IP
address in dotted decimal notation (eg. 44.0.0.1), or as a sym-
bolic name listed in the file domain.txt.
All commands and many subcommands may be abbreviated. You only
need type enough of a command's name to distinguish it from
others that begin with the same series of letters. Parameters,
however, must be typed in full.
Certain FTP subcommands (eg. put, get, dir, etc) are recognized
only in converse mode with the appropriate FTP session; they are
not recognized in command mode. (See the FTP Subcommands chap-
ter.)
Note that certain commands may have been configured out of a
given copy of net.exe to save disk and memory. If a command has
been configured out, it will not appear in the list produced by
the "?" command, nor will it be recognized by the command inter-
preter.
3.1. <CR>
Entering a carriage return (empty line) while in command mode
puts you in converse mode with the current session. If there is
May 28, 1991
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no current session, net.exe remains in command mode.
3.2. !
An alias for the shell command.
3.3. #
Commands starting with the hash mark (#) are ignored. This is
mainly useful for comments in the autoexec.net file.
3.4. abort [<session #>]
Abort a FTP get, put or dir operation in progress. If issued
without an argument, the current session is aborted. (This com-
mand works only on FTP sessions.) When receiving a file, abort
simply resets the data connection; the next incoming data packet
will generate a TCP RST (reset) response to clear the remote
server. When sending a file, abort sends a premature end-of-
file. Note that in both cases abort will leave a partial copy of
the file on the destination machine, which must be removed manu-
ally if it is unwanted.
3.5. arp
Display the Address Resolution Protocol table that maps IP
addresses to their subnet (link) addresses on subnetworks capable
of broadcasting. For each IP address entry the subnet type (eg.
Ethernet, AX.25), subnet address and time to expiration is shown.
If the link address is currently unknown, the number of IP data-
grams awaiting resolution is also shown.
3.5.1. arp add <hostid> ethernet | ax25 <ethernet address> |
<ax25_address>
Add a permanent entry to the table. It will not time out as will
an automatically-created entry, but must be removed with the arp
drop command.
3.5.2. arp publish <hostid> ethernet | ax25 <ethernet address> |
<ax25_address>
This command is similar to the arp add command, but system will
also respond to any ARP request it sees on the network that seeks
the specified address. Use this feature with great care.
3.5.3. arp drop <hostid> ax25 | ethernet
Remove the specified entry from the ARP table.
3.5.4. arp flush
Drop all automatically-created entries in the ARP table. Perma-
nent entries are not affected.
3.6. asystat
Display statistics on attached asynchronous communications inter-
faces (8250 or 16550A), if any. The display for each port con-
sists of three lines. The first line gives the port label and the
configuration flags; these indicate whether the port is a 16550A
chip, the trigger character if any, whether CTS flow control is
enabled, whether RLSD (carrier detect) line control is enabled,
May 28, 1991
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and the speed in bits per second. (Receiving the trigger charac-
ter causes the driver to signal upper layer software that data is
ready; it is automatically set to the appropriate frame end char-
acter for SLIP, PPP and NRS lines.)
The second line of the status display shows receiver (RX) event
counts: the total number of receive interrupts, received charac-
ters, receiver overruns (lost characters) and the receiver high
water mark. The high water mark is the maximum number of charac-
ters ever read from the device during a single interrupt. This is
useful for monitoring system interrupt latency margins as it
shows how close the port hardware has come to overflowing due to
the inability of the CPU to respond to a receiver interrupt in
time. 8250 chips have no FIFO, so the high water mark cannot go
higher than 2 before overruns occur. The 16550A chip, however,
has a 16-byte receive FIFO which the software programs to inter-
rupt the CPU when the FIFO is one-quarter full. The high water
mark should typically be 4 or 5 when a 16550A is used; higher
values indicate that the CPU has at least once been slow to
respond to a receiver interrupt.
When the 16550A is used, a count of FIFO timeouts is also dis-
played on the RX status line. These are generated automatically
by the 16550A when three character intervals go by with more than
0 but less than 4 characters in the FIFO. Since the characters
that make up a SLIP or NRS frame are normally sent at full line
speed, this count will usually be a lower bound on the number of
frames received on the port, as only the last fragment of a frame
generally results in a timeout (and then only when the frame is
not a multiple of 4 bytes long.)
Finally, the software fifo overruns and high water mark are dis-
played. These indicate whether the <bufsize> parameter on the
attach command needs to be adjusted (see the Attach Commands
chapter).
The third line shows transmit (TX) statistics, including a total
count of transmit interrupts, transmitted characters, the length
of the transmit queue in bytes, the number of status interrupts,
and the number of THRE timeouts. The status interrupt count will
be zero unless CTS flow control or RLSD line control has been
enabled. The THRE timeout is a stopgap measure to catch lost
transmit interrupts, which seem to happen when there is a lot of
activity (ideally, this will be zero).
3.7. attach <hw type> ...
Configure and attach a hardware interface to the system.
Detailed instructions for each driver are in the Attach Commands
chapter. An easy way to obtain a summary of the parameters
required for a given device is to issue a partial attach command
(eg. attach packet). This produces a usage message giving the
complete command format.
3.8. ax25 ...
These commands are used to control the AX.25 amateur radio link
level protocol.
May 28, 1991
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3.8.1. ax25 blimit [<count>]
Display or set the AX25 retransmission backoff limit. Normally
each successive AX25 retransmission is delayed by twice the value
of the previous interval; this is called binary exponential back-
off. When the backoff reaches the blimit setting it is held at
that value, which defaults to 30. To prevent the possibility of
"congestive collapse" on a loaded channel, blimit should be set
at least as high as the number of stations sharing the channel.
Note that this is applicable only on actual AX25 connections; UI
frames will never be retransmitted by the AX25 layer.
3.8.2. ax25 dest
Display the AX25 destination monitoring database. Each callsign
seen in the destination field of an AX25 frame is displayed (most
recent first), along with the time since it was last referenced.
The time since the same callsign was last seen in the source
field of an AX25 frame on the same interface is also shown. If
the callsign has never been seen in the source field of a frame,
then this field is left blank. (This indicates that the destina-
tion is either a multicast address or a "hidden station".)
3.8.3. ax25 digipeat [on | off]
Display or set the digipeater enable flag.
3.8.4. ax25 flush
Clear the AX.25 "heard" list (see ax25 heard).
3.8.5. ax25 heard
Display the AX.25 "heard" list. For each interface that is con-
figured to use AX.25, a list of all callsigns heard through that
interface is shown, along with a count of the number of packets
heard from each station and the interval, in hr:min:sec format,
since each station was last heard. The list is sorted in most-
recently-heard order. The local station is included in the list-
ing; the packet count reflects the number of packets transmitted.
This count will be correct whether or not the modem monitors its
own transmissions.
3.8.6. ax25 irtt [<milliseconds>]
Display or set the initial value of smoothed round trip time to
be used when a new AX25 connection is created. The value is in
milliseconds. The actual round trip time will be learned by mea-
surement once the connection has been established.
3.8.7. ax25 kick <axcb>
Force a retransmission on the specified AX.25 control block.
3.8.8. ax25 maxframe [<count>]
Establish the maximum number of frames that will be allowed to
remain unacknowledged at one time on new AX.25 connections. This
number cannot be greater than 7.
May 28, 1991
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3.8.9. ax25 mycall [<call>]
Display or set the local AX.25 address. The standard format is
used (eg. KA9Q-0 or WB6RQN-5). This command must be given before
any attach commands using AX.25 mode are given.
3.8.10. ax25 paclen [<size>]
Limit the size of I-fields on new AX.25 connections. If IP data-
grams or fragments larger than this are transmitted, they will be
transparently fragmented at the AX.25 level, sent as a series of
I frames, and reassembled back into a complete IP datagram or
fragment at the other end of the link. To have any effect on IP
datagrams, this parameter should be less than or equal to the MTU
of the associated interface.
3.8.11. ax25 pthresh [<size>]
Display or set the poll threshold to be used for new AX.25 Ver-
sion 2 connections. The poll threshold controls retransmission
behavior as follows. If the oldest unacknowledged I-frame size is
less than the poll threshold, it will be sent with the poll (P)
bit set if a timeout occurs. If the oldest unacked I-frame size
is equal to or greater than the threshold, then a RR or RNR
frame, as appropriate, with the poll bit set will be sent if a
timeout occurs.
The idea behind the poll threshold is that the extra time needed
to send a "small" I-frame instead of a supervisory frame when
polling after a timeout is small, and since there's a good chance
the I-frame will have to be sent anyway (i.e., if it were lost
previously) then you might as well send it as the poll. But if
the I-frame is large, send a supervisory (RR/RNR) poll instead to
determine first if retransmitting the oldest unacknowledged I-
frame is necessary; the timeout might have been caused by a lost
acknowledgement. This is obviously a tradeoff, so experiment
with the poll threshold setting. The default is 128 bytes, one
half the default value of paclen.
3.8.12. ax25 reset <axcb>
Delete the AX.25 connection control block at the specified
address.
3.8.13. ax25 retry [<count>]
Limit the number of successive unsuccessful retransmission
attempts on new AX.25 connections. If this limit is exceeded,
link re-establishment is attempted. If this fails retry times,
then the connection is abandoned and all queued data is deleted.
A value of 0 means "infinity"; the retry limit is disabled.
retry
3.8.14. ax25 route
Display the AX.25 routing table that specifies the digipeaters to
be used in reaching a given station.
3.8.14.1. ax25 route add <target> [digis ... ]
Add an entry to the AX.25 routing table. An automatic ax25 route
add is executed if digipeaters are specified in an AX25 connect
May 28, 1991
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command, or if a connection is received from a remote station via
digipeaters. Such automatic routing table entries won't override
locally created entries, however.
3.8.14.2. ax25 route drop <target>
Drop an entry from the AX.25 routing table.
3.8.15. ax25 status [<axcb>]
Without an argument, display a one-line summary of each AX.25
control block. If the address of a particular control block is
specified, the contents of that control block are dumped in more
detail. Note that the send queue units are frames, while the
receive queue units are bytes.
3.8.16. ax25 t3 [<milliseconds>]
Display or set the AX.25 idle "keep alive" timer. Value is in
milliseconds.
3.8.17. ax25 version [1 | 2]
Display or set the version of the AX.25 protocol to attempt to
use on new connections. The default is 1 (the version that does
not use the poll/final bits).
3.8.18. ax25 window [<size>]
Set the number of bytes that can be pending on an AX.25 receive
queue beyond which I frames will be answered with RNR (Receiver
Not Ready) responses. This presently applies only to suspended
interactive AX.25 sessions, since incoming I-frames containing
network (IP, NET/ROM) packets are always processed immediately
and are not placed on the receive queue. However, when an AX.25
connection carries both interactive and network packet traffic,
an RNR generated because of backlogged interactive traffic will
also stop network packet traffic from being sent.
3.9. BOOTP
The bootp client and server are added to KA9Q to provide auto-
matic configuration capabilities. With this suite of extensions,
a KA9Q host can automatically configure its IP address, subnet
mask, broadcast address, host name, the default gateway, the name
servers, and default boot file. This simplifies host configura-
tion.
The bootp server supports dynamic IP address assignment. If a
bootp request is made by a host to the server, and the server
doesn't have a static record for the PC making the request, an IP
address may be assigned from a list of dynamic addresses. This
simplifies server configuration, so that machines don't require
prior IP address assignment. This is useful in environments such
as university dormitories, where network service is provided, and
the computers configurations change frequently. When the server
list of free addresses reaches a minimum threshold, it will begin
attempts to reclaim the address.
The bootp client and server code are written according to RFC 951
and 1048.
May 28, 1991
- 9 -
3.9.1. bootp [<net_name>] [silent] [noisy]
Send a request to a bootp server, and wait for a reply. On
receipt of the server reply, the information is used to configure
the host. If a reply is not received, the command will time out.
Without arguments, bootp sends a request to the first interface
in the interface list.
This command requires that there exist a routing entry for the IP
broadcast address 255.255.255.255 pointing to the appropriate
interface. If the interface uses ARP, there must also be an ARP
entry that maps that address to the appropriate link level broad-
cast address. For example, if you have an Ethernet interface
named "ethernet", use the following commands before the bootp
command:
route add 255.255.255.255 ethernet
arp add 255.255.255.255 ether ff:ff:ff:ff:ff:ff
The following bootp subcommands are available:
3.9.1.1. bootp <net_name>
Send a request over the specified network.
3.9.1.2. bootp silent
Set bootp so that it will not print the configuration.
3.9.1.3. bootp noisy
Set bootp so that it will print the configuration.
3.9.2. bootpd [start] [stop] [dns] [dynip] [host] [rmhost]
[homedir] [defaultfile] [logfile] [logscreen]
This command starts and stops the bootp server, and sets the con-
figuration for the information it will provide in replies. If
the file bootptab exists, it will read the file for configuration
information. On receipt of a request, if bootptab has been
changed, the server will reread the file for the changed configu-
ration. The following subcommands are available:
3.9.2.1. bootpd start
Start the bootp server, reading from the file bootptab for con-
figuration information.
3.9.2.2. bootpd stop
Stop the bootp server.
3.9.2.3. bootpd dns
Print the address of the domain name servers supplied in replies.
3.9.2.4. bootpd dns <IP addr of domain name server>...
Set the addresses.
3.9.2.5. bootpd dynip
Print the range and use of the dynamic IP address.
May 28, 1991
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3.9.2.6. bootpd dynip <net_name> <IP address> <IP address>
Set the range of IP address to be used for network netname.
These address will be supplied to hosts that are not found in the
static record.
3.9.2.7. bootpd dynip <netname> off
Turn off dynamic ip for network interface netname.
3.9.2.8. bootpd host
Print the information in the static host table.
3.9.2.9. bootpd host <hostname> ethernet|ax25 <ethernet
addr>|<ax25 addr> <ip addr> [boot file]
Add a host to the host table. The LANSTAR packet drivers provide
an Ethernet interface to upper layer applications, so configure a
LANSTAR network as an Ethernet.
3.9.2.10. bootpd rmhost <hostname>
Remove host <hostname> from the static host tables.
3.9.2.11. bootpd homedir
Print the default directory for the bootp file name used when the
bootp file is not specified in the static host record, and when
dynamic addresses are supplied. Default is the null string.
3.9.2.12. bootpd homedir <directory name>
Set the default directory.
3.9.2.13. bootpd defaultfile
Print the default file for the bootp file name used when the
bootp file is not specified in the static host record, and when
dynamic addresses are supplied. Default is the null string.
3.9.2.14. bootpd defaultfile <filename>
Set the default file.
3.9.2.15. bootpd logfile
Print the status of logging to a log file.
3.9.2.16. bootpd logfile <filename | default> on|off
Sets the file for logging to <filename> or the default, bootplog.
Turn logging to that file on or off.
3.9.2.17. bootpd logscreen
Print the status of logging to the screen.
3.9.2.18. bootpd logscreen on|off
Turn logging to the screen on or off.
3.10. cd [<dirname>]
Change the current working directory, and display the new set-
ting. Without an argument, cd simply displays the current direc-
tory without change. The pwd command is an alias for cd.
May 28, 1991
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3.11. close [<session>]
Close the specified session; without an argument, close the cur-
rent session. On an AX.25 session, this command initiates a dis-
connect. On a FTP or Telnet session, this command sends a FIN
(i.e., initiates a close) on the session's TCP connection. This
is an alternative to asking the remote server to initiate a close
(QUIT to FTP, or the logout command appropriate for the remote
system in the case of Telnet). When either FTP or Telnet sees
the incoming half of a TCP connection close, it automatically
responds by closing the outgoing half of the connection. Close
is more graceful than the reset command, in that it is less
likely to leave the remote TCP in a "half-open" state.
3.12. connect <iface> <callsign> [<digipeater> ... ]
Initiate a "vanilla" AX.25 session to the specified call sign
using the specified interface. Data sent on this session goes out
in conventional AX.25 packets with no upper layer protocol. The
de-facto presentation standard format is used, in that each
packet holds one line of text, terminated by a carriage return.
A single AX.25 connection may be used for terminal-to-terminal,
IP and NET/ROM traffic. The three types of data are automati-
cally separated by their AX.25 Level 3 Protocol IDs.
Up to 7 optional digipeaters may be given; note that the word via
is NOT needed. If digipeaters are specified, they are automati-
cally added to the AX25 routing table as though the ax25 route
add command had been given before issuing the connect command.
3.13. delete <filename>
Delete a filename in the current working directory.
3.14. detach <iface>
Detach a previously attached interface from the system. All IP
routing table entries referring to this interface are deleted,
and forwarding references by any other interface to this inter-
face are removed.
3.15. dialer <iface> <seconds> <hostid> <pings> <dialer-file>
Setup an autodialer session for the interface. Whenever the
interface is idle for the interval in <seconds>, the autodialer
will ping the <hostid>. If there is no answer after <pings>
attempts, the autodialer will execute the special commands con-
tained in the <dialer-file>.
If the interval in <seconds> is zero, a previous dialer command
process will be removed. If the number of <pings> is zero, the
<dialer-file> will be executed without pinging the <hostid>.
The file may have any valid name, and must be located in the con-
figuration directory (see the Installion section). The commands
in the file are described in the Dialer Subcommands chapter.
3.16. dir [<dirname>]
List the contents of the specified directory on the console. If
no argument is given, the current directory is listed. Note that
this command works by first listing the directory into a tempo-
rary file, and then creating a more session to display it. After
May 28, 1991
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this completes, the temporary file is deleted.
3.17. disconnect [<session #>]
An alias for the close command (for the benefit of AX.25 users).
3.18. domain ...
These commands control the operation of the Internet Domain Name
Service (DNS).
3.18.1. domain addserver <hostid>
Add one or more domain name server(s) to the list of name
servers.
3.18.2. domain dropserver <hostid>
Remove one or more domain name server(s) from the list of name
servers.
3.18.3. domain listservers
List the currently configured domain name servers, along with
statistics on how many queries and replies have been exchanged
with each one, response times, etc.
3.18.4. domain query <hostid>
Send a query to a domain server asking for all resource records
associated with this <hostid>, and list the records.
3.18.5. domain retry [<count>]
Display or set the number of attempts to reach each server on the
list during one call to the resolver. If this count is exceeded,
a failure indication is returned. If set to 0, the list will
cycle forever; this may be useful for unattended operation. The
default is 3.
3.18.6. domain suffix [<domain suffix>]
Display or specify the default domain name suffix to be appended
to a host name when it contains no periods. For example, if the
suffix is set to ampr.org and the user enters telnet ka9q, the
domain resolver will attempt to find ka9q.ampr.org. If the host
name being sought contains one or more periods, however, the
default suffix is NOT applied (eg. telnet foo.bar would NOT be
turned into foo.bar.ampr.org).
3.18.7. domain trace [on | off]
Display or set the flag controlling the tracing of domain server
requests and responses. Trace messages will be seen only if a
domain name being sought is not found in the local cache file,
domain.txt.
3.18.8. domain cache ...
These commands are used for the use of the resource record file
domain.txt, and the local memory cache.
May 28, 1991
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3.18.8.1. domain cache clean [on | off]
Display or set the flag controlling the removal of resource
records from the domain.txt file whose time-to-live has reached
zero.
When clean is off (the default), expired records will be
retained; if no replacement can be obtained from another domain
name server, these records will continue to be used.
When clean is on, expired records will be removed from the file
whenever any new record is added to the file.
3.18.8.2. domain cache list
List the current contents of the local memory cache.
3.18.8.3. domain cache size [<count>]
Display or set the nominal maximum size of the local memory
cache. The default is 20.
(Note: The cache may be temporarily larger when waiting for new
records to be written to the domain.txt file.)
3.18.8.4. domain cache wait [<seconds>]
Display or set the interval in seconds to wait for additional
activity before updating the domain.txt file. The default is 300
seconds (5 minutes).
3.19. echo [accept | refuse]
Display or set the flag controlling client Telnet's response to a
remote WILL ECHO offer.
The Telnet presentation protocol specifies that in the absence of
a negotiated agreement to the contrary, neither end echoes data
received from the other. In this mode, a Telnet client session
echoes keyboard input locally and nothing is actually sent until
a carriage return is typed. Local line editing is also performed:
backspace deletes the last character typed, while control-U
deletes the entire line.
When communicating from keyboard to keyboard the standard local
echo mode is used, so the setting of this parameter has no
effect. However, many timesharing systems (eg. UNIX) prefer to do
their own echoing of typed input. (This makes screen editors
work right, among other things). Such systems send a Telnet WILL
ECHO offer immediately upon receiving an incoming Telnet connec-
tion request. If echo accept is in effect, a client Telnet ses-
sion will automatically return a DO ECHO response. In this mode,
local echoing and editing is turned off and each key stroke is
sent immediately (subject to the congestion control algorithms in
TCP). While this mode is just fine across an Ethernet, it is
clearly inefficient and painful across slow paths like packet
radio channels. Specifying echo refuse causes an incoming WILL
ECHO offer to be answered with a DONT ECHO; the client Telnet
session remains in the local echo mode. Sessions already in the
remote echo mode are unaffected. (Note: Berkeley Unix has a bug
in that it will still echo input even after the client has
refused the WILL ECHO offer. To get around this problem, enter
the stty -echo command to the shell once you have logged in.)
May 28, 1991
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3.20. eol [unix | standard]
Display or set Telnet's end-of-line behavior when in remote echo
mode. In standard mode, each key is sent as-is. In unix mode,
carriage returns are translated to line feeds. This command is
not necessary with all UNIX systems; use it only when you find
that a particular system responds to line feeds but not carriage
returns. Only SunOS release 3.2 seems to exhibit this behavior;
later releases are fixed.
3.21. escape [<char>]
Display or set the current command-mode escape character in hex.
(This command is not provided on the IBM-PC; on the PC, the
escape char is always F10.)
3.22. etherstat
Display 3-Com Ethernet controller statistics (if configured).
3.23. exit
Exit the net.exe program and return to MS-DOS.
3.24. finger <user@hostid> [<user@hostid> ...]
Issue a network finger request for user user at host hostid. This
creates a client session which may be interrupted, resumed,
reset, etc, just like a Telnet client session.
3.25. ftp <hostid>
Open an FTP control channel to the specified remote host and
enter converse mode on the new session. Responses from the
remote server are displayed directly on the screen. See the FTP
Subcommands chapter for descriptions of the commands available in
a FTP session.
3.26. help
Display a brief summary of top-level commands.
3.27. hop ...
These commands are used to test the connectivity of the network.
3.27.1. hop check <hostid>
Initiate a hopcheck session to the specified host. This uses a
series of UDP "probe" packets with increasing IP TTL fields to
determine the sequence of gateways in the path to the specified
destination. This function is patterned after the UNIX traceroute
facility.
ICMP message tracing should be turned off before this command is
executed (see the icmp trace command).
3.27.2. hop maxttl [<hops>]
Display or set the maximum TTL value to be used in hop check ses-
sions. This effectively bounds the radius of the search.
3.27.3. hop maxwait [<seconds>]
Display or set the maximum interval that a hopcheck session will
wait for responses at each stage of the trace. The default is 5
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seconds.
3.27.4. hop queries [<count>]
Display or set the number of UDP probes that will be sent at each
stage of the trace. The default is 3.
3.27.5. hop trace [on | off]
Display or set the flag that controls the display of additional
information during a hop check session.
3.28. hostname [<name>]
Display or set the local host's name. By convention this should
be the same as the host's primary domain name. This string is
used only in the greeting messages of the various network
servers; note that it does NOT set the system's IP address.
If <name> is the same as an <iface> (see the Attach commands
chapter), this command will search for a CNAME domain resource
record which corresponds to the IP address of the <iface>.
3.29. hs
Display statistics about the HS high speed HDLC driver (if con-
figured and active).
3.30. icmp ...
These commands are used for the Internet Control Message Protocol
service.
3.30.1. icmp echo [on | off]
Display or set the flag controlling the asynchronous display of
ICMP Echo Reply packets. This flag must be on for one-shot pings
to work (see the ping command.)
3.30.2. icmp status
Display statistics about the Internet Control Message Protocol
(ICMP), including the number of ICMP messages of each type sent
or received.
3.30.3. icmp trace [on | off]
Display or set the flag controlling the display of ICMP error
messages. These informational messages are generated by Internet
routers in response to routing, protocol or congestion problems.
This option should be turned off before using the hop check
facility because it relies on ICMP Time Exceeded messages, and
the asynchronous display of these messages will be mingled with
hop check command output.
3.31. ifconfig
Display a list of interfaces, with a short status for each.
3.31.1. ifconfig <iface>
Display an extended status of the interface.
May 28, 1991
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3.31.2. ifconfig <iface> broadcast <address>
Set the broadcast address for the interface. The <address> takes
the form of an IP address with 1's in the host part of the
address. This is related to the netmask sub-command. See also
the arp command.
3.31.3. ifconfig <iface> encapsulation <name>
Not fully implemented.
3.31.4. ifconfig <iface> forward <forward-iface>
Set a forwarding interface for multiple channel interfaces. To
remove the forward, set <forward-iface> to <iface>.
3.31.5. ifconfig <iface> ipaddress <hostid>
Set the IP address for this interface. It is standard Internet
practice that each interface has its own address. For hosts with
only one interface, the interface address is usually the same as
the host address. See also the hostname and ip address commands.
3.31.6. ifconfig <iface> linkaddress <hardware-dependant>
Set the hardware dependant address for this interface.
3.31.7. ifconfig <iface> mtu <mtu>
Set the MTU for this interface. See the Setting ... MTU, MSS and
Window chapter for more information.
3.31.8. ifconfig <iface> netmask <address>
Set the sub-net mask for this interface. The <address> takes the
form of an IP address with 1's in the network and subnet parts of
the address, and 0's in the host part of the address. This is
related to the broadcast sub-command. See also the route com-
mand.
3.31.9. ifconfig <iface> rxbuf <?>
Not yet implemented.
3.32. ip ...
These commands configure the Internet Protocol (IP) service.
3.32.1. ip address [<hostid>]
Display or set the default local IP address. This command must be
given before an attach command if it is to be used as the default
IP address for the interface.
3.32.2. ip rtimer [<seconds>]
Display or set the IP reassembly timeout. The default is 30 sec-
onds.
3.32.3. ip status
Display Internet Protocol (IP) statistics, such as total packet
counts and error counters of various types.
May 28, 1991
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3.32.4. ip ttl [<hops>]
Display or set the time-to-live value placed in each outgoing IP
datagram. This limits the number of switch hops the datagram
will be allowed to take. The idea is to bound the lifetime of the
packet should it become caught in a routing loop, so make the
value slightly larger than the number of hops across the network
you expect to transit packets. The default is set at compilation
time to the official recommended value for the Internet.
3.33. isat [on | off]
Display or set the AT flag. Currently, there is no sure-fire way
to determine the type of clock-chip being used. If an AT type
clock is in use, this command will allow measurement of time in
milliseconds, rather than clock ticks (55 milliseconds per clock
tick).
3.33.1. kick [<session>]
Kick all sockets associated with a session; if no argument is
given, kick the current session. Performs the same function as
the ax25 kick and tcp kick commands, but is easier to type.
3.34. log [stop | <filename>]
Display or set the filename for logging server sessions. If stop
is given as the argument, logging is terminated (the servers
themselves are unaffected). If a file name is given as an argu-
ment, server session log entries will be appended to it.
3.35. mbox
Display the status of the mailbox server system (if configured).
3.36. memory ...
These commands are used to display memory allocation statistics.
3.36.1. memory free
Display the storage allocator free list. Each entry consists of a
starting address, in hex, and a size, in decimal bytes.
3.36.2. memory ibuffs
Display or set the number of buffers on the interrupt buffer
pool. The default is 5.
3.36.3. memory ibufsize
Display or set the size of each buffer on the interrupt buffer
pool. Since the interrupt buffer pool consists of fixed-size
buffers, the value chosen must be large enough to satisfy the
needs of the most demanding driver. The default is 2048.
3.36.4. memory sizes
Display a histogram of storage allocator request sizes. Each his-
togram bin is a binary order of magnitude (i.e., a factor of 2).
3.36.5. memory status
Display a summary of storage allocator statistics. The first line
shows the base address of the heap, its total size, the amount of
May 28, 1991
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heap memory available in bytes and as a percentage of the total
heap size, and the amount of memory left over (i.e., not placed
on the heap at startup) and therefore available for shell subcom-
mands.
The second line shows the total number of calls to allocate and
free blocks of memory, the difference of these two values (i.e.,
the number of allocated blocks outstanding), the number of allo-
cation requests that were denied due to lack of memory, and the
number of calls to free() that attempted to free garbage (eg. by
freeing the same block twice or freeing a garbled pointer).
The third line shows the number of calls to malloc and free that
occurred with interrupts off. In normal situations these values
should be zero. The fourth line shows statistics for the special
pool of fixed-size buffers used to satisfy requests for memory at
interrupt time. The variables shown are the number of buffers
currently in the pool, their size, and the number of requests
that failed due to exhaustion of the pool.
3.37. mkdir <dirname>
Create a sub-directory in the current working directory.
3.38. mode <iface> [vc | datagram]
Control the default transmission mode on the specified AX.25
interface. In datagram mode, IP packets are encapsulated in
AX.25 UI frames and transmitted without any other link level
mechanisms, such as connections or acknowledgements.
In vc (virtual circuit) mode, IP packets are encapsulated in
AX.25 I frames and are acknowledged at the link level according
to the AX.25 protocol. Link level connections are opened if nec-
essary.
In both modes, ARP is used to map IP to AX.25 addresses. The
defaults can be overridden with the type-of-service (TOS) bits in
the IP header. Turning on the "reliability" bit causes I frames
to be used, while turning on the "low delay" bit uses UI frames.
(The effect of turning on both bits is undefined and subject to
change).
In both modes, IP-level fragmentation is done if the datagram is
larger than the interface MTU. In virtual circuit mode, how-
ever, the resulting datagram (or fragments) is further fragmented
at the AX.25 layer if it (or they) are still larger than the
AX.25 paclen parameter. In AX.25 fragmentation, datagrams are
broken into several I frames and reassembled at the receiving end
before being passed to IP. This is preferable to IP fragmentation
whenever possible because of decreased overhead (the IP header
isn't repeated in each fragment) and increased robustness (a lost
fragment is immediately retransmitted by the link layer).
3.39. more <file> [<file> ...]
Display the specified file(s) a screen at a time. To proceed to
the next screen, press the space bar; to cancel the display, hit
the 'q' key. The more command creates a session that you can
suspend and resume just like any other session.
May 28, 1991
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3.40. param <iface> [<param> [value]] ...
Invoke a device-specific control routine. The following parame-
ter names are recognized by the parameter command, but not all
are supported by each device type. Most commands deal only with
half-duplex packet radio interfaces.
TxDelay - transmit keyup delay
Persist - P-persistence setting
SlotTime - persistence slot time setting
txTail - transmit done holdup delay
FullDup - enable/disable full duplex
Hardware - hardware specific command
TxMute - experimental transmit mute command
DTR - control Data Terminal Ready (DTR) signal to modem
RTS - control Request to Send (RTS) signal to modem
Speed - set line speed
EndDelay
Group
Idle
Min
MaxKey
Wait
Down - drop modem control lines
Up - raise modem control lines
Return - return a KISS TNC to command mode
Depending on the interface, some parameters can be read back by
omitting a new value. This is not possible with KISS TNCs as
there are no KISS commands for reading back previously sent
parameters.
On a KISS TNC interface, the param command generates and sends
control packets to the TNC. Data bytes are treated as decimal.
For example, param ax0 txdelay 255 will set the keyup timer
(type field = 1) on the KISS TNC configured as ax0 to 2.55 sec-
onds (255 x .01 sec). On all asy interfaces (slip, kiss/ax25,
nrs, ppp) the param <iface> speed command allows the baud rate to
be read or set.
The implementation of this command for the various interface
drivers is incomplete and subject to change.
3.41. ping <hostid> [<length> [<seconds> [<incflag>]]]
Ping (send ICMP Echo Request packets to) the specified host. By
default the data field contains only a small timestamp to aid in
determining round trip time; if the optional length argument is
given, the appropriate number of data bytes (consisting of hex
55) are added to the ping packets.
If interval is specified, pings will be repeated indefinitely at
the specified number of seconds; otherwise a single, "one shot"
ping is done. Responses to one-shot pings appear asynchronously
on the command screen, while repeated pings create a session that
may be suspended and resumed. Pinging continues until the ses-
sion is manually reset.
The incflag option causes a repeated ping to increment the target
IP address for each ping; it is an experimental feature for
searching blocks of IP addresses for active hosts.
May 28, 1991
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3.42. ppp ...
These commands are used to configure Point to Point Protocol
interfaces.
This implementation of PPP is designed to be as complete as pos-
sible. Because of this, the number of options can be rather
daunting. However, a typical PPP configuration might include the
following commands:
attach asy 0x3f8 4 ppp pp0 4096 1500 9600
dial pp0 30 <hostid> 3 dialer.pp0
#
ppp pp0 lcp local accm 0
ppp pp0 lcp local compress address on
ppp pp0 lcp local compress protocol on
ppp pp0 lcp local magic on
ppp pp0 lcp open active
#
ppp pp0 ipcp local compress tcp 16 1
ppp pp0 ipcp open active
#
route add default pp0
3.42.1. ppp <iface>
Display the status of the PPP interface.
3.42.2. ppp <iface> lcp ...
These commands are used for the LCP [Link Control Protocol] con-
figuration.
3.42.2.1. ppp <iface> lcp close
Shutdown the PPP interface.
3.42.2.2. ppp <iface> lcp local ...
These commands control the configuration of the local side of the
link. If an option is specified, the parameters will be used as
the initial values in configuration requests. If not specified,
that option will not be requested.
For each of these options, the allow parameter will permit the
remote to include that option in its response, even when the
option is not included in the request. By default, all options
are allowed.
3.42.2.2.1. ppp <iface> lcp local accm [ <bitmap> | allow [on |
off] ]
Display or set the Async Control Character Map. The default is
0xffffffff.
3.42.2.2.2. ppp <iface> lcp local authenticate [ pap | none |
allow [on | off] ]
Display or set the authentication protocol. The default is none.
3.42.2.2.3. ppp <iface> lcp local compress address/control [ on
| off | allow [on | off] ]
Display or set the option to compress the address and control
fields of the PPP HLDC-like header. This is generally desirable
May 28, 1991
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for slow asynchronous links, and undesirable for fast or syn-
chronous links. The default is off.
3.42.2.2.4. ppp <iface> lcp local compress protocol [ on | off |
allow [on | off] ]
Display or set the option to compress the protocol field of the
PPP HLDC-like header. This is generally desirable for slow asyn-
chronous links, and undesirable for fast or synchronous links.
The default is off.
3.42.2.2.5. ppp <iface> lcp local magic [ on | off | <value> |
allow [on | off] ]
Display or set the initial Magic Number. The default is off
(zero).
3.42.2.2.6. ppp <iface> lcp local mru [ <size> | allow [on |
off] ]
Display or set the Maximum Receive Unit. The default is 1500.
3.42.2.2.7. ppp <iface> lcp local default
Reset the options to their default values.
3.42.2.3. ppp <iface> lcp open active | passive
Wait for the physical layer to come up. If active, initiate con-
figuration negotiation. If passive, wait for configuration nego-
tiation from the remote.
3.42.2.4. ppp <iface> lcp remote ...
These commands control the configuration of the remote side of
the link. The options are identical to those of the local side.
If an option is specified, the parameters will be used in
responses to the remote's configuration requests. If not speci-
fied, that option will be accepted if it is allowed.
For each of these options, the allow parameter will permit the
remote to specify that option in its request. By default, all
options are allowed.
3.42.2.5. ppp <iface> lcp timeout [<seconds>]
Display or set the interval to wait between configuration or ter-
mination attempts. The default is 3 seconds.
3.42.2.6. ppp <iface> lcp try ...
These commands are used for the various counters.
3.42.2.6.1. ppp <iface> lcp try configure [<count>]
Display or set the number of configuration requests sent. The
default is 10.
3.42.2.6.2. ppp <iface> lcp try failure [<count>]
Display or set the number of bad configuration requests allowed
from the remote. The default is 5.
May 28, 1991
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3.42.2.6.3. ppp <iface> lcp try terminate [<count>]
Display or set the number of termination requests sent before
shutdown. The default is 2.
3.42.3. ppp <iface> ipcp ...
These commands are used for the IPCP [Internet Protocol Control
Protocol] configuration.
The close, open, timeout and try sub-commands are identical to
the LCP (described above).
3.42.3.1. ppp <iface> ipcp local ...
These commands control the configuration of the local side of the
link. If an option is specified, the parameters will be used as
the initial values in configuration requests. If not specified,
that option will not be requested.
For each of these options, the allow parameter will permit the
remote to include that option in its response, even when the
option is not included in the request. By default, all options
are allowed.
3.42.3.1.1. ppp <iface> ipcp local address [ <hostid> | allow
[on | off] ]
Display or set the local address for negotiation purposes. If an
address of 0 is specified, the other side of the link will supply
the address. By default, no addresses are negotiated.
3.42.3.1.2. ppp <iface> ipcp local compress [ tcp <slots>
[<flag>] | none | allow [on | off] ]
Display or set the compression protocol. The default is none.
The tcp <slots> specifies the number of "conversation" slots,
which must be 1 to 255. (This may be limited at compilation time
to a smaller number.) A good choice is in the range 4 to 16.
The tcp <flag> is 0 (don't compress the slot number) or 1 (OK to
compress the slot number). KA9Q can handle compressed slot num-
bers, so the default is 1.
3.42.3.2. ppp <iface> ipcp remote ...
These commands control the configuration of the remote side of
the link. The options are identical to those of the local side.
If an option is specified, the parameters will be used in
responses to the remote's configuration requests. If not speci-
fied, that option will be accepted if it is allowed.
For each of these options, the allow parameter will permit the
remote to specify that option in its request. By default, all
options are allowed.
3.42.4. ppp <iface> pap ...
These commands are used for the PAP [Password Authentication Pro-
tocol] configuration.
The timeout and try sub-commands are identical to the LCP
(described above). However, the terminate counter is unused.
May 28, 1991
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3.42.4.1. ppp <iface> pap user [ <username> [<password>] ]
Display or set the username (the password may be set, but not
displayed). When the username is specified, but no password is
supplied, the ftpusers file is searched for the password. When a
username/password is unknown or rejected, a session will appear
at the console to prompt for a new username/password.
3.42.5. ppp <iface> trace [<flags>]
Display or set the flags that control the logging of information
during PPP link configuration.
The flag value is 0 for none, 1 for basic, and 2 for general.
Values greater than 2 are usually not compiled, and are described
in the appropriate source files where they are defined.
3.43. ps
Display all current processes in the system. The fields are as
follows:
PID - Process ID (the address of the process descriptor).
SP - The current value of the process stack pointer.
stksize - The size of the stack allocated to the process.
maxstk - The apparent peak stack utilization of this process.
This is done in a somewhat heuristic fashion, so the numbers
should be treated as approximate. If this number reaches or
exceeds the stksize figure, the system is almost certain to
crash; the net.exe program should be recompiled to give the pro-
cess a larger allocation when it is started.
event - The event this task is waiting for, if it is not
runnable.
fl - Process status flags. There are three: I (Interrupts
enabled), W (Waiting for event) and S (Suspended). The I flag is
set whenever a task has executed a pwait() call (wait for event)
without first disabling hardware interrupts. Only tasks that wait
for hardware interrupt events will turn off this flag; this is
done to avoid critical sections and missed interrupts. The W flag
indicates that the process is waiting for an event; the event
column will be non-blank. Note that although there may be several
runnable processes at any time (shown in the ps listing as those
without the W flag and with blank event fields) only one process
is actually running at any one instant (The Refrigerator Light
Effect says that the ps command is always the one running when
this display is generated.)
3.44. pwd [<dirname>]
An alias for the cd command.
3.45. record [off | <filename>]
Append to filename all data received on the current session.
Data sent on the current session is also written into the file
except for Telnet sessions in remote echo mode. The command
record off stops recording and closes the file.
3.46. remote [-p <port>] [-k <key>] [-a <kickaddr>] <hostid>
exit | reset | kick
Send a UDP packet to the specified host commanding it to exit the
May 28, 1991
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net.exe program, reset the processor, or force a retransmission
on TCP connections. For this command to be accepted, the remote
system must be running the remote server and the port number
specified in the remote command must match the port number given
when the server was started on the remote system. If the port
numbers do not match, or if the remote server is not running on
the target system, the command packet is ignored. Even if the
command is accepted there is no acknowledgement.
The kick command forces a retransmission timeout on all TCP con-
nections that the remote node may have with the local node. If a
connection is idle, a current ACK packet (without data) is sent.
If the -a option is used, connections to the specified host are
kicked instead. No key is required for the kick subcommand.
The exit and reset subcommands are mainly useful for restarting
the net.exe program on a remote unattended system after the con-
figuration file has been updated. The remote system should
invoke the net.exe program automatically upon booting, preferably
in an infinite loop. For example, under MS-DOS the boot disk
should contain the following in autoexec.net:
:loop
net
goto :loop
3.47. remote -s <key>
The exit and reset subcommands of remote require a password. The
password is set on a given system with the -s option, and it is
specified in a command to a remote system with the -k option. If
no password is set with the -s option, then the exit and reset
subcommands are disabled.
Note that remote is an experimental feature in NOS; it is not yet
supported by any other TCP/IP implementation.
3.48. rename <oldfilename> <newfilename>
Rename oldfilename to newfilename.
3.49. reset [<session>]
Reset the specified session; if no argument is given, reset the
current session. This command should be used with caution since
it does not reliably inform the remote end that the connection no
longer exists. (In TCP a reset (RST) message will be automati-
cally generated should the remote TCP send anything after a local
reset has been done. In AX.25 the DM message performs a similar
role. Both are used to get rid of a lingering half-open connec-
tion after a remote system has crashed.)
3.50. rip ...
These commands are used for the RIP service.
3.50.1. rip accept <gateway>
Remove the specified gateway from the RIP filter table, allowing
future broadcasts from that gateway to be accepted.
May 28, 1991
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3.50.2. rip add <hostid> <seconds> [<flags>]
Add an entry to the RIP broadcast table. The IP routing table
will be sent to hostid every interval seconds. If flags is speci-
fied as 1, then "split horizon" processing will be performed for
this destination. That is, any IP routing table entries pointing
to the interface that will be used to send this update will be
removed from the update. If split horizon processing is not
specified, then all routing table entries except those marked
"private" will be sent in each update. (Private entries are
never sent in RIP packets).
Triggered updates are always done. That is, any change in the
routing table that causes a previously reachable destination to
become unreachable will trigger an update that advertises the
destination with metric 15, defined to mean "infinity".
Note that for RIP packets to be sent properly to a broadcast
address, there must exist correct IP routing and ARP table
entries that will first steer the broadcast to the correct inter-
face and then place the correct link-level broadcast address in
the link-level destination field. If a standard IP broadcast
address convention is used (eg. 128.96.0.0 or 128.96.255.255)
then chances are you already have the necessary IP routing table
entry, but unusual subnet or cluster-addressed networks may
require special attention. However, an arp add command will be
required to translate this address to the appropriate link level
broadcast address. For example,
arp add 128.96.0.0 ethernet ff:ff:ff:ff:ff:ff
for an Ethernet network, and
arp add 44.255.255.255 ax25 qst-0
for an AX25 packet radio channel.
3.50.3. rip drop <dest>
Remove an entry from the RIP broadcast table.
3.50.4. rip merge [on | off]
This flag controls an experimental feature for consolidating
redundant entries in the IP routing table. When rip merging is
enabled, the table is scanned after processing each RIP update.
An entry is considered redundant if the target(s) it covers would
be routed identically by a less "specific" entry already in the
table. That is, the target address(es) specified by the entry in
question must also match the target addresses of the less spe-
cific entry and the two entries must have the same interface and
gateway fields. For example, if the routing table contains
Dest Len Interface Gateway Metric P Timer Use
1.2.3.4 32 ethernet0 128.96.1.2 1 0 0 0
1.2.3 24 ethernet0 128.96.1.2 1 0 0 0
then the first entry would be deleted as redundant since packets
sent to 1.2.3.4 will still be routed correctly by the second
May 28, 1991
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entry. Note that the relative metrics of the entries are ignored.
3.50.5. rip refuse <gateway>
Refuse to accept RIP updates from the specified gateway by adding
the gateway to the RIP filter table. It may be later removed with
the rip accept command.
3.50.6. rip request <gateway>
Send a RIP Request packet to the specified gateway, causing it to
reply with a RIP Response packet containing its routing table.
3.50.7. rip status
Display RIP status, including a count of the number of packets
sent and received, the number of requests and responses, the num-
ber of unknown RIP packet types, and the number of refused RIP
updates from hosts in the filter table. A list of the addresses
and intervals to which periodic RIP updates are being sent is
also shown, along with the contents of the filter table.
3.50.8. rip trace [0 | 1 | 2]
This variable controls the tracing of incoming and outgoing RIP
packets. Setting it to 0 disables all RIP tracing. A value of 1
causes changes in the routing table to be displayed, while pack-
ets that cause no changes cause no output. Setting the variable
to 2 produces maximum output, including tracing of RIP packets
that cause no change in the routing table.
3.51. rmdir <dirname>
Remove a sub-directory from the current working directory.
3.52. route
With no arguments, route displays the IP routing table.
3.52.1. route add <dest_hostid>[/bits] | default <iface>
[<gateway_hostid> [<metric>]]
This command adds an entry to the routing table. It requires at
least two more arguments, the hostid of the target destination
and the name of the interface to which its packets should be
sent. If the destination is not local, the gateway's hostid
should also be specified. (If the interface is a point-to-point
link, then gateway_hostid may be omitted even if the target is
non-local because this field is only used to determine the gate-
way's link level address, if any. If the destination is directly
reachable, gateway_hostid is also unnecessary since the destina-
tion address is used to determine the interface link address).
The optional /bits suffix to the destination host id specifies
how many leading bits in the host id are to be considered signif-
icant in the routing comparisons. If not specified, 32 bits
(i.e., full significance) is assumed. With this option, a single
routing table entry may refer to many hosts all sharing a common
bit string prefix in their IP addresses. For example, ARPA Class
A, B and C networks would use suffixes of /8, /16 and /24 respec-
tively; the command
route add 44/8 sl0 44.64.0.2
May 28, 1991
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causes any IP addresses beginning with "44" in the first 8 bits
to be routed to 44.64.0.2; the remaining 24 bits are "don't-
cares".
When an IP address to be routed matches more than one entry in
the routing table, the entry with largest bits parameter (i.e.,
the "best" match) is used. This allows individual hosts or blocks
of hosts to be exceptions to a more general rule for a larger
block of hosts.
The special destination default is used to route datagrams to
addresses not matched by any other entries in the routing table;
it is equivalent to specifying a /bits suffix of /0 to any desti-
nation hostid. Care must be taken with default entries since two
nodes with default entries pointing at each other will route
packets to unknown addresses back and forth in a loop until their
time-to-live (TTL) fields expire. (Routing loops for specific
addresses can also be created, but this is less likely to occur
accidentally). The best way to use default routes is to pick one
node in your network that has the "best" connections to the world
outside your network. Create a spanning tree with that node as
the root and have each node install a default route pointing in
the direction of that node, with the exception of the root node.
Here are some examples of the route command:
# Route datagrams to IP address 44.0.0.3 to SLIP line #0.
# No gateway is needed because SLIP is point-to point.
route add 44.0.0.3 sl0
# Route all default traffic to the gateway on the local Ethernet
# with IP address 44.0.0.1
route add default ec0 44.0.0.1
# The local Ethernet has an ARPA Class-C address assignment;
# route all IP addresses beginning with 192.4.8 to it
route add 192.4.8/24 ec0
# The station with IP address 44.0.0.10 is on the local AX.25 channel
route add 44.0.0.10 ax0
3.52.2. route addprivate <dest hostid>[/bits] | default <iface>
[<gateway hostid> [<metric>]]
This command is identical to route add except that it also marks
the new entry as private; it will never be included in outgoing
RIP updates.
3.52.3. route drop <dest hostid>
route drop deletes an entry from the table. If a packet arrives
for the deleted address and a default route is in effect, it will
be used.
3.53. session [<session #>]
Without arguments, displays the list of current sessions, includ-
ing session number, remote TCP or AX.25 address and the associ-
ated socket index. An asterisk (*) is shown next to the current
session; entering a blank line at this point puts you in converse
mode with that session. Entering a session number as an argument
May 28, 1991
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to the session command will put you in converse mode with that
session. If the Telnet server is enabled, the user is notified
of an incoming request and a session number is automatically
assigned. The user may then select the session normally to con-
verse with the remote user as though the session had been locally
initiated.
3.54. shell
Suspends net.exe and executes a sub-shell ("command processor"
under MS-DOS). When the sub-shell exits, net.exe resumes (under
MS-DOS, enter the exit command). Background activity (FTP
servers, etc) is also suspended while the subshell executes. Note
that this will fail unless there is sufficient unused memory for
the sub-shell and whatever command the user tries to run.
3.55. smtp ...
These commands control the operation of the Simple Mail Transfer
Protocol (that is, mail).
3.55.1. smtp gateway [<hostid>]
Displays or sets the host to be used as a "smart" mail relay. Any
mail sent to a host not in the host table will instead be sent to
the gateway for forwarding.
3.55.2. smtp kick
Run through the outgoing mail queue and attempt to deliver any
pending mail. This command allows the user to "kick" the mail
system manually. Normally, this command is periodically invoked
by a timer whenever net.exe is running.
3.55.3. smtp maxclients [<count>]
Displays or sets the maximum number of simultaneous outgoing SMTP
sessions that will be allowed. The default is 10; reduce it if
network congestion is a problem.
3.55.4. smtp timer [<seconds>]
Displays or sets the interval between "kicks" (scans) of the out-
bound mail queue. For example, smtp timer 600 will cause the sys-
tem to check for outgoing mail every 10 minutes and attempt to
deliver anything it finds, subject of course to the smtp max-
clients limit. Setting a value of zero disables queue scanning
altogether, note that this is the default! This value is recom-
mended for stand alone IP gateways that never handle mail, since
it saves wear and tear on the floppy disk drive.
3.55.5. smtp trace [<value>]
Displays or sets the trace flag in the SMTP client, allowing you
to watch SMTP's conversations as it delivers mail. Zero (the
default) disables tracing.
3.56. socket [<socket #>]
Without an argument, displays all active sockets, giving their
index and type, the address of the associated protocol control
block and the and owner process ID and name. If the index to an
May 28, 1991
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active socket is supplied, the status display for the appropriate
protocol is called. For example, if the socket refers to a TCP
connection, the display will be that given by the tcp status com-
mand with the protocol control block address.
3.57. start ax25 | discard | echo | ftp | netrom | remote | smtp
| telnet | ttylink
Start the specified Internet server, allowing remote connection
requests.
3.58. stop ax25 | discard | echo | ftp | netrom | remote | smtp
| telnet | ttylink
Stop the specified Internet server, rejecting any further remote
connect requests. Existing connections are allowed to complete
normally.
3.59. tcp ...
These commands are used for the Transmission Control Protocol
service.
3.59.1. tcp irtt [<milliseconds>]
Display or set the initial round trip time estimate, in millisec-
onds, to be used for new TCP connections until they can measure
and adapt to the actual value. The default is 5000 milliseconds
(5 seconds). Increasing this when operating over slow channels
will avoid the flurry of retransmissions that would otherwise
occur as the smoothed estimate settles down at the correct value.
Note that this command should be given before servers are started
in order for it to have effect on incoming connections.
TCP also caches measured round trip times and mean deviations
(MDEV) for current and recent destinations. Whenever a new TCP
connection is opened, the system first looks in this cache. If
the destination is found, the cached IRTT and MDEV values are
used. If not, the default IRTT value mentioned above is used,
along with a MDEV of 0. This feature is fully automatic, and it
can improve performance greatly when a series of connections are
opened and closed to a given destination (eg. a series of FTP
file transfers or directory listings).
3.59.2. tcp kick <tcb_addr>
If there is unacknowledged data on the send queue of the speci-
fied TCB, this command forces an immediate retransmission.
3.59.3. tcp mss [<size>]
Display or set the TCP Maximum Segment Size in bytes that will be
sent on all outgoing TCP connect request (SYN segments). This
tells the remote end the size of the largest segment (packet) it
may send. Changing MSS affects only future connections; existing
connections are unaffected.
3.59.4. tcp reset <tcb_addr>
Deletes the TCP control block at the specified address.
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3.59.5. tcp rtt <tcb_addr> <rtt> <mdev>
Replaces the automatically computed round trip time and mean
deviation values in the specified TCB with new values in mil-
liseconds. This command is useful to speed up recovery from a
series of lost packets since it provides a manual bypass around
the normal backoff retransmission timing mechanisms.
3.59.6. tcp status [<tcb_addr>]
Without arguments, displays several TCP-level statistics, plus a
summary of all existing TCP connections, including TCB address,
send and receive queue sizes, local and remote sockets, and con-
nection state. If tcb_addr is specified, a more detailed dump of
the specified TCB is generated, including send and receive
sequence numbers and timer information.
3.59.7. tcp window [<size>]
Displays or sets the default receive window size in bytes to be
used by TCP when creating new connections. Existing connections
are unaffected.
3.60. telnet <hostid>
Creates a Telnet session to the specified host and enters con-
verse mode.
3.61. tip <iface>
Creates a tip session that connects to the specified interface in
"dumb terminal" mode. The interface must have already been
attached with the attach command. Any packet traffic (IP data-
grams, etc) routed to the interface while this session exists
will be discarded. To close a tip session, use the reset com-
mand. It will then revert to normal slip, nrs or kiss mode opera-
tion.
This feature is primarily useful for manually establishing SLIP
connections. At present, only the built-in "com" ports can be
used with this command.
3.62. trace [<iface> [off | <btio> [<tracefile>]]]
Controls packet tracing by the interface drivers. Specific bits
enable tracing of the various interfaces and the amount of infor-
mation produced. Tracing is controlled on a per-interface basis;
without arguments, trace gives a list of all defined interfaces
and their tracing status. Output can be limited to a single
interface by specifying it, and the control flags can be change
by specifying them as well. The flags are given as a hexadecimal
number which is interpreted as follows:
May 28, 1991
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O - Enable tracing of output packets if 1, disable if 0
I - Enable tracing of input packets if 1, disable if 0
T - Controls type of tracing:
0 - Protocol headers are decoded, but data is not displayed
1 - Protocol headers are decoded, and data (but not the
headers themselves) are displayed as ASCII characters,
64 characters/line. Unprintable characters are displayed
as periods.
2 - Protocol headers are decoded, and the entire packet
(headers AND data) is also displayed in hexadecimal
and ASCII, 16 characters per line.
B - Broadcast filter flag. If set, only packets specifically addressed
to this node will be traced; broadcast packets will not be displayed.
If tracefile is not specified, tracing will be to the console.
3.63. udp status
Displays the status of all UDP receive queues.
3.64. upload [<filename>]
Opens filename and sends it on the current session as though it
were typed on the terminal.
3.65. watch
Displays the current software stopwatch values, with min and max
readings for each. This facility allows a programmer to measure
the execution time of critical sections of code with microsecond
resolution. This command is supported only on the IBM PC, and
the meaning of each stopwatch value depends on where the calls
have been inserted for test purposes; the distribution copy of
net.exe usually has no stopwatch calls.
3.66. ?
Same as the help command.
4. Attach Commands
This chapter details the attach commands for the various hardware
interface drivers. Not all of these drivers may be configured
into every net.exe binary; a list of the available types may be
obtained by entering the command attach ?.
Some parameters are accepted by several drivers. They are:
4.0.1. <bufsize>
For asynchronous devices (eg. COM ports operating in SLIP or NRS
mode) this parameter specifies the size of the receiver's ring
buffer. It should be large enough to hold incoming data at full
line speed for the longest time that the system may be busy in
MS-DOS or the BIOS doing a slow I/O operation (eg. to a floppy
disk). A kilobyte is usually more than sufficient.
For synchronous devices (eg. the scc, hs, pc100, hapn and drsi
interfaces operating in HDLC mode), the bufsize parameter speci-
fies the largest packet that may be received on the interface.
This should be set by mutual agreement among stations sharing the
channel. For standard AX.25 with a maximum I-frame data size of
256 bytes, a value of 325 should provide an adequate safety
May 28, 1991
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margin. On higher speed channels (eg. 56kb/s) larger values (eg.
2K bytes) will provide much better performance and allow full-
sized Ethernet packets to be carried without fragmentation.
4.0.2. <ioaddr>
The base address of the interface's control registers, in hex.
4.0.3. <vector>
The interface's hardware interrupt (IRQ) vector, in hex.
4.0.4. <iface>
The name (an arbitrary character string) to be assigned to this
interface. It is used to refer to the interface in ifconfig and
route commands and in trace output.
4.0.5. <mtu>
The Maximum Transmission Unit size, in bytes. Datagrams larger
than this limit will be fragmented at the IP layer into smaller
pieces. For AX.25 UI frames, this limits the size of the informa-
tion field. For AX.25 I frames, however, the ax25 paclen parame-
ter is also relevant. If the datagram or fragment is still
larger than paclen, it is also fragmented at the AX.25 level (as
opposed to the IP level) before transmission. (See the ax25
paclen command for further information).
4.0.6. <speed>
The speed in bits per second (eg. 2400).
4.1. attach 3c500 <ioaddr> <vector> arpa <iface> <qlen> <mtu>
[<ip_addr>]
Attach a 3Com 3C501 Ethernet interface. qlen is the maximum
allowable transmit queue length. If the ip_addr parameter is not
given, the value associated with a prior ip address command will
be used.
The use of this driver is not recommended; use the packet driver
interface with the loadable 3C501 packet driver instead.
4.2. attach asy <ioaddr> <vector> ax25 | nrs | ppp | slip
<iface> <bufsize> <mtu> <speed> [<crv>]
Attach a standard PC "com port" (asynchronous serial port), using
the National 8250 or 16550A chip. Standard values on the IBM PC
and clones for ioaddr and vector are 0x3f8 and 4 for COM1, and
0x2f8 and 3 for COM2. If the port uses a 16550A chip, it will be
detected automatically and the FIFOs enabled.
4.2.1. ax25
Similar to slip, except that an AX.25 header and a KISS TNC con-
trol header are added to the front of the datagram before SLIP
encoding. Either UI (connectionless) or I (connection-oriented)
AX.25 frames can be used; see the mode command for details.
4.2.2. nrs
Use the NET/ROM asynchronous framing technique for communication
with a local NET/ROM TNC.
May 28, 1991
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4.2.3. ppp
Point-to-Point-Protocol. Encapsulates datagrams in an HDLC-like
frame. This is a new Internet standard for point-to-point commu-
nication, compatible with CCITT standards.
4.2.4. slip
Serial Line Internet Protocol. Encapsulates IP datagrams
directly in SLIP frames without a link header. This is for opera-
tion on point-to-point lines and is compatible with 4.2BSD UNIX
SLIP.
4.2.5. <crv>
The optional flags are a string of characters "crv": c enables
RTS/CTS detection, r enables RLSD (Carrier Detect) physical line
sensing, v enables Van Jacobson TCP/IP Header Compression, and is
valid only for SLIP.
4.3. attach drsi <ioaddr> <vector> ax25 <iface> <bufsize> <mtu>
<ch_a_speed> <ch_b_speed>
N6TTO driver for the Digital Radio Systems PCPA 8530 card. Since
there are two channels on the board, two interfaces are attached.
They will be named iface with 'a' and 'b' appended. bufsize is
the receiver buffer size in bytes; it must be larger than the
largest frame to be received. ch_a_speed and ch_b_speed are the
speeds, in bits/sec, for the A and B channels, respectively.
4.4. attach eagle <ioaddr> <vector> ax25 <iface> <bufsize> <mtu>
<speed>
WA3CVG/NG6Q driver for the Eagle Computer card (Zilog 8530).
4.5. attach hapn <ioaddr> <vector> ax25 <iface> <bufsize> <mtu>
csma | full
KE3Z driver for the Hamilton Amateur Packet Network adapter
(Intel 8273). The csma | full parameter specifies whether the
port should operate in carrier sense multiple access (CSMA) mode
or in full duplex.
4.6. attach hs <ioaddr> <vector> ax25 <iface> <bufsize> <mtu>
<keyup_delay> <p>
Attach a DRSI PCPA or Eagle Computer interface card using a spe-
cial "high speed" 8530 driver. This driver uses busy-wait loops
to send and receive each byte instead of interrupts, making it
usable with high speed modems (such as the WA4DSY 56kb/s modem)
on slow systems. This does have the side effect of "freezing"
the system whenever the modem transmitter or receiver is active.
This driver can operate only in CSMA mode, and it is recommended
that no other interfaces requiring small interrupt latencies be
attached to the same machine.
The keyup_delay parameter specifies the transmitter keyup delay
in milliseconds. The p value specifies the transmitter persis-
tence value in the range 1-255; the corresponding slot time is
fixed at one hardware clock tick, about 55 ms on the PC.
As with the other 8530 drivers, this driver actually attaches two
interfaces, one for each 8530 channel.
May 28, 1991
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4.7. attach packet <intvec> <iface> <txqlen> <mtu>
Attach a separate software "packet driver" meeting the FTP Soft-
ware, Inc, Software Packet Driver specification. The driver must
have already been installed as a TSR (e.g., by invocation in
autoexec.bat). Packet drivers in the Ethernet, ARCNET, SLIP,
SLFP, and KISS/AX25 classes are supported.
intvec is the software interrupt vector used for communication to
the packet driver, and txqlen is the maximum number of packets
that will be allowed on the transmit queue.
4.8. attach pc100 <ioaddr> <vector> ax25 <iface> <bufsize>
<speed>
Driver for the PACCOMM PC-100 (Zilog 8530) card. Only AX.25
operation is supported.
4.9. attach scc <devices> init <addr> <spacing> <Aoff> <Boff>
<Dataoff> <intack> <vec> [p|r]<clock> [<hdwe>] [<param>]
PE1CHL driver to initialize a generic SCC (8530) interface board
prior to actually attaching it. The parameters are as follows:
4.9.1. <devices>
The number of SCC chips to support.
4.9.2. <addr>
The base address of the first SCC chip (hex).
4.9.3. <spacing>
The spacing between the SCC chip base addresses.
4.9.4. <Aoff>
The offset from a chip's base address to its channel A control
register.
4.9.5. <Boff>
The offset from a chip's base address to its channel B control
register.
4.9.6. <Dataoff>
The offset from each channel's control register to its data reg-
ister.
4.9.7. <intack>
The address of the INTACK/Read Vector port. If none, specify 0 to
read from RR3A/RR2B.
4.9.8. <vec>
The CPU interrupt vector for all connected SCCs.
4.9.9. <clock>
The clock frequency (PCLK/RTxC) of all SCCs in hertz. Prefix
with 'p' for PCLK, 'r' for RTxC clock (for baudrate gen).
May 28, 1991
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4.9.10. <hdwe>
Optional hardware type. The following values are currently sup-
ported: 1 - Eagle card, 2 - PACCOMM PC-100, 4 - PRIMUS-PC card
(DG9BL), 8 - DRSI PCPA card.
4.9.11. <param>
Optional extra parameter. At present, this is used only with the
PC-100 and PRIMUS-PC cards to set the modem mode. The value 0x22
is used with the PC-100 and 0x2 is used with the PRIMUS-PC card.
The attach scc ... init command must be given before the inter-
faces are actually attached with the following command.
4.10. attach scc <chan> slip | kiss | nrs | ax25 <iface> <mtu>
<speed> <bufsize> [<call>]
Attach an initialized SCC port to the system. The parameters are
as follows:
4.10.1. <chan>
The SCC channel number to attach, 0 or 1 for the first chip's A
or B port, 2 or 3 for the second chip's A or B port, etc.
4.10.2. slip | kiss | nrs | ax25
The operating mode of the interface. slip, kiss and nrs all oper-
ate the port hardware in asynchronous mode; slip is Internet-
standard serial line IP mode, kiss generates SLIP frames contain-
ing KISS TNC commands and AX.25 packets and nrs uses NET/ROM
local serial link framing conventions to carry NET/ROM packets.
Selecting ax25 mode puts the interface into synchronous HDLC mode
that is suitable for direct connection to a half duplex radio
modem.
4.10.3. <speed>
The interface speed in bits per second (eg. 1200). Prefix with
'd' when an external divider is available to generate the TX
clock. When the clock source is PCLK, this can be a /32 divider
between TRxC and RTxC. When the clock is at RTxC, the TX rate
must be supplied at TRxC. This is needed only for full duplex
synchronous operation. When this arg is given as 'ext', the
transmit and receive clocks are external, and the internal baud
rate generator (BRG) and digital phase locked loop (DPLL) are not
used.
4.11. Attach Examples
Here are some examples of the attach command:
May 28, 1991
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# Attach a 3Com Ethernet controller using the standard 3Com address and
# vector (i.e., as it comes out of the box) to use ARPA-standard encapsulation.
# The receive queue is limited to 5 packets, and outgoing packets larger
# than 1500 bytes will be fragmented
attach 3c500 0x300 3 arpa ec0 5 1500
# Attach the PC asynch card normally known as "com1" (the first controller)
# to operate in point-to-point slip mode at 9600 baud, calling it "sl0".
# A 1024 byte receiver ring buffer is allocated. Outgoing packets larger
# than 256 bytes are fragmented.
attach asy 0x3f8 4 slip sl0 1024 256 9600
# Attach the secondary PC asynch card ("com2") to operate in AX.25 mode
# with an MTU of 576 bytes at 9600 baud with a KISS TNC, calling it "ax0".
# By default, IP datagrams are sent in UI frames
attach asy 0x2f8 3 ax25 ax0 1024 576 9600
# Attach the packet driver loaded at interrupt 0x7e
# The packet driver is for an Ethernet interface
attach packet 0x7e ethernet 8 1500
5. FTP Subcommands
During converse mode with an FTP server, everything typed on the
console is first examined to see if it is a locally-known com-
mand. If not, the line is passed intact to the remote server on
the control channel. If it is one of the following commands, how-
ever, it is executed locally. (Note that this generally involves
other commands being sent to the remote server on the control
channel.)
5.1. dir [<file> | <directory> [<local file>]]
Without arguments, dir requests that a full directory listing of
the remote server's current directory be sent to the terminal.
If one argument is given, this is passed along in the LIST com-
mand; this can be a specific file or subdirectory that is mean-
ingful to the remote file system. If two arguments are given, the
second is taken as the local file into which the directory list-
ing should be put (instead of being sent to the console). The
PORT command is used before the LIST command is sent.
5.2. get <remote file> [<local file>]
Asks the remote server to send the file specified in the first
argument. The second argument, if given, will be the name of the
file on the local machine; otherwise it will have the same name
as on the remote machine. The PORT and RETR commands are sent on
the control channel.
5.3. hash
A synonym for the verbose 3 command.
5.4. ls [<file> | <directory> [<local file>]]
ls is identical to the dir command except that the "NLST" command
is sent to the server instead of the "LIST" command. This results
in an abbreviated directory listing, i.e., one showing only the
May 28, 1991
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file names themselves without any other information.
5.5. mget <file> [<file> ...]
Fetch a collection of files from the server. File names may
include wild card characters; they will be interpreted and
expanded into a list of files by the remote system using the NLST
command. The files will have the same name on the local system
that they had on the server.
5.6. mkdir <remote directory>
Creates a directory on the remote machine.
5.7. mput <file> [<file> ...]
Send a collection of files to the server. File names may include
wild card characters; they will be expanded locally into a list
of files to be sent. The files will have the same name on the
server as on the local system.
5.8. put <local file> [<remote file>]
Asks the remote server to accept data, creating the file named in
the first argument. The second argument, if given, will be the
name of the file on the remote machine; otherwise it will have
the same name as on the local machine. The PORT and STOR com-
mands are sent on the control channel.
5.9. rmdir <remote directory>
Deletes a directory on the remote machine.
5.10. type [a | i | l <bytesize>]
Tells both the local client and remote server the type of file
that is to be transferred. The default is 'a', which means ASCII
(i.e., a text file). Type 'i' means image, i.e., binary. In
ASCII mode, files are sent as varying length lines of text in
ASCII separated by cr/lf sequences; in IMAGE mode, files are sent
exactly as they appear in the file system. ASCII mode should be
used whenever transferring text between dissimilar systems (eg.
UNIX and MS-DOS) because of their different end-of-line and/or
end-of-file conventions. When exchanging text files between
machines of the same type, either mode will work but IMAGE mode
is usually faster. Naturally, when exchanging raw binary files
(executables, compressed archives, etc) IMAGE mode must be used.
Type 'l' (logical byte size) is used when exchanging binary files
with remote servers having oddball word sizes (eg. DECSYSTEM-10s
and 20s). Locally it works exactly like IMAGE, except that it
notifies the remote system how large the byte size is. bytesize
is typically 8. The type command sets the local transfer mode
and generates the TYPE command on the control channel.
5.11. verbose [0 | 1 | 2 | 3]
Set or display the level of message output in file transfers.
Verbose 0 gives the least output, and verbose 3 the most, as fol-
lows:
May 28, 1991
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0 - Display error messages only.
1 - Display error messages plus a one-line summary after each transfer
giving the name of the file, its size, and the transfer time and rate.
2 - Display error and summary messages plus the progress messages generated
by the remote FTP server. (This setting is the default.)
3 - Display all messages. In addition, a "hash mark" (#) is displayed for
every 1,000 bytes sent or received.
If a command is sent to the remote server because it is not rec-
ognized locally, the response is always displayed, regardless of
the setting of verbose. This is necessary for commands like pwd
(display working directory), which would otherwise produce no
message at all if verbose were set to 0 or 1.
6. Dialer Subcommands
Each dialer command may (should) have a different dialer file.
The file resides in the configuration directory, as specified in
the Installation section (see chapter 1). A typical dialer file
might be:
# Set the speed, and toggle DTR to ensure modem is in command mode.
control down
wait 3000
speed 2400
control up
wait 3000
# Dial, and wait for connection
send "atdt555-1212\r"
wait 45000 "CONNECT " speed
wait 2000
# PAD specific initialization
send "\r"
wait 15000 "Terminal ="
send "ppp\r"
wait 10000 "\r\n"
6.0.1. control down | up
Control asy interface. The down option drops DTR and RTS. The
up option asserts DTR and RTS.
6.0.2. send "string"
This dialer command will write the specified string to the inter-
face. The string quote marks are required, and the string may
not contain embedded control characters. However, the standard C
string escape sequences are recognized (\0 should not be used).
6.0.3. speed [ 9600 | 4800 | 2400 | 1200 | 300 ]
This dialer command will set the speed of the interface to one of
the available speeds. If the speed is missing, the speed will be
displayed in the dialer session window.
6.0.4. wait <milliseconds> [ "test string" ] [ speed ]
If only the time is specified, the dialer pauses for the desired
number of milliseconds.
Otherwise, the dialer reads until the test string is detected on
the interface. If the string is not detected within the desired
May 28, 1991
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time, the autodialer will reset. The string quote marks are
required, and the string may not contain embedded control charac-
ters. However, the standard C string escape sequences are recog-
nized (\0 should not be used).
Finally, if the speed parameter is specified, the dialer will
continue to read characters until a non-digit is detected. The
string read is converted to an integer, and used to set the
interface speed. If the trailing non-digit is not detected
within the desired time, or the integer value is not a valid
speed, the autodialer will reset. The speed feature is useful
for reading back the CONNECT <speed> message generated by Hayes-
compatible modems.
7. The /ftpusers File
Since MS-DOS is a single-user operating system (some might say it
is a glorified bootstrap loader), it provides no access control;
all files can be read, written or deleted by the local user. It
is usually undesirable to give such open access to a system to
remote network users. Net.exe therefore provides its own access
control mechanisms.
The file /ftpusers controls remote FTP and mailbox access. The
FTP default is no access; if this file does not exist, the FTP
server will be unusable. A remote user must first "log in" to
the system with the USER and PASS commands, giving a valid name
and password listed in /ftpusers, before he or she can transfer
files.
Each entry in /ftpusers consists of a single line of the form
username password /path permissions
There must be exactly four fields, and there must be exactly one
space between each field. Comments may be added after the last
field. Comment lines begin with '#' in column one.
username is the user's login name.
password is the required password. Note that this is in plain
text; therefore it is not a good idea to give general read per-
mission to the root directory. A password of '*' (a single
asterisk) means that any password is acceptable.
/path is the allowable prefix on accessible files. Before any
file or directory operation, the current directory and the user-
specified file name are joined to form an absolute path name in
"canonical" form (i.e., a full path name starting at the root,
with "./" and "../" references, as well as redundant /'s, recog-
nized and removed). The result MUST begin with the allowable
path prefix; if not, the operation is denied. This field must
always begin with a "/", i.e., at the root directory.
permissions is a decimal number granting permission for read,
create and write operations. If the low order bit (0x1) is set,
the user is allowed to read a file subject to the path name pre-
fix restriction. If the next bit (0x2) is set, the user is
allowed to create a new file if it does not overwrite an existing
file. If the third bit (0x4) is set, the user is allowed to
write a file even if it overwrites an existing file, and in addi-
tion he may delete files. Again, all operations are allowed sub-
ject to the path name prefix restrictions. Permissions may be
combined by adding bits, for example, 0x3 (= 0x2 + 0x1) means
May 28, 1991
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that the user is given read and create permission, but not over-
write/delete permission.
For example, suppose /ftpusers on machine pc.ka9q.ampr.org con-
tains the line
friendly test /testdir 7
A session using this account would look like this:
net> ftp pc.ka9q.ampr.org
Resolving pc.ka9q.ampr.org... Trying 128.96.160.1...
FTP session 1 connected to pc.ka9q.ampr.org
220 pc.ka9q.ampr.org FTP version 900418 ready at Mon May 7 16:27:18 1990
Enter user name: friendly
331 Enter PASS command
Password: test [not echoed]
230 Logged in
ftp>
The user now has read, write, overwrite and delete privileges for
any file under /testdir; he may not access any other files.
Here are some more sample entries in /ftpusers:
karn foobar / 7 # User "karn" with password "foobar" may read,
# write, overwrite and delete any file on the
# system.
guest bletch /g/bogus 3 # User "guest" with password "bletch" may read
# any file under /g/bogus and its subdirectories,
# and may create a new file as long as it does
# not overwrite an existing file. He may NOT
# delete any files.
anonymous * /public 1 # User "anonymous" (any password) may read files
# under /public and its subdirectories; he may
# not create, overwrite or delete any files.
This last entry is the standard convention for keeping a reposi-
tory of public files; in particular, the username "anonymous" is
an established ARPA convention.
8. The domain.txt File
Net.exe translates domain names (eg. "pc.ka9q.ampr.org") to IP
addresses (eg. 128.96.160.3) through the use of an Internet
Domain Name resolver and a local "cache" file, domain.txt. When-
ever the user specifies a domain name, the local cache is
searched for the desired entry. If it is present, it is used; if
not, and if domain name server(s) have been configured, a query
is sent over the network to the current server. If the server
responds, the answer is added to the domain.txt file for future
use. If the server does not respond, any additional servers on
the list are tried in a round-robin fashion until one responds,
or the retry limit is reached (see the domain retry command). If
domain.txt does not contain the desired entry and there are no
configured domain name servers, then the request immediately
fails.
If a domain name server is available, and if all references to
host-ids in your /autoexec.net file are in IP address format,
then it is possible to start with a completely empty domain.txt
file and have net.exe build it for you. However, you may wish to
May 28, 1991
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add your own entries to domain.txt, either because you prefer to
use symbolic domain names in your /autoexec.net file or you don't
have access to a domain server and you need to create entries for
all of the hosts you may wish to access.
Each entry takes one line, and the fields are separated by any
combination of tabs or spaces. For example:
pc.ka9q.ampr.org. IN A 128.96.160.3
IN is the class of the record. It means Internet, and it will be
found in all entries. A is the type of the record, and it means
that this is an address record. Domain name pc.ka9q.ampr.org
therefore has Internet address 128.96.160.3.
Another possible entry is the CNAME (Canonical Name) record. For
example:
ka9q.ampr.org. IN CNAME pc.ka9q.ampr.org.
This says that domain name "ka9q.ampr.org" is actually an alias
for the system with (primary, or canonical) domain name
"pc.ka9q.ampr.org." When a domain name having a CNAME record is
given to net.exe, the system automatically follows the reference
to the canonical name and returns the IP address associated with
that entry.
Entries added automatically by net.exe will have an additional
field between the domain name and the class (IN) field. For
example:
pc.ka9q.ampr.org. 3600 IN A 128.96.160.3
This is the time-to-live value, in seconds, associated with the
record received from the server. Clients (such as net.exe)
caching these records are supposed to delete them after the time-
to-live interval has expired, allowing for the possibility that
the information in the record may become out of date.
This implementation of net.exe will decrement the TTL to zero,
but will not delete the record unless the "clean" flag is on (see
the domain cache clean command). When a remote server is not
available, the old entry will be used.
When the TTL value is missing (as in the examples above), the
record will never expire, and must be managed by hand. Since
domain.txt is a plain text file, it may be easily edited by the
user to add, change or delete records.
Additional types of records include MX (mail exchanger), NS (name
server) and SOA (start of authority) may appear in domain.txt
from remote server responses. Only MX is currently used by
net.exe (in the mailbox). The others are retained for future
development (such as the incorporation of a smarter resolver or a
full-blown domain name server).
9. Setting Bufsize, Paclen, Maxframe, MTU, MSS and Window
Many net.exe users are confused by these parameters and do not
know how to set them properly. This chapter will first review
these parameters and then discuss how to choose values for them.
Special emphasis is given to avoiding interoperability problems
that may appear when communicating with non-net.exe implementa-
tions of AX.25.
May 28, 1991
- 42 -
9.1. Hardware Parameters
9.1.1. Bufsize
This parameter is required by most of net.exe's built-in HDLC
drivers (eg. those for the DRSI PCPA and the Paccomm PC-100). It
specifies the size of the buffer to be allocated for each
receiver port. HDLC frames larger than this value cannot be
received.
There is no default bufsize; it must be specified in the attach
command for the interface.
9.2. AX25 Parameters
9.2.1. Paclen
Paclen limits the size of the data field in an AX.25 I-frame.
This value does not include the AX.25 protocol header (source,
destination and digipeater addresses).
Since unconnected-mode (datagram) AX.25 uses UI frames, this
parameter has no effect in unconnected mode.
The default value of paclen is 256 bytes.
9.2.2. Maxframe
This parameter controls the number of I-frames that net.exe may
send on an AX.25 connection before it must stop and wait for an
acknowledgement. Since the AX.25/LAPB sequence number field is 3
bits wide, this number cannot be larger than 7.
Since unconnected-mode (datagram) AX.25 uses UI frames that do
not have sequence numbers, this parameter does not apply to
unconnected mode.
The default value of maxframe in net.exe is 1.
9.3. IP and TCP Parameters
9.3.1. MTU
The MTU (Maximum Transmission Unit) is an interface parameter
that limits the size of the largest IP datagram that it may han-
dle. IP datagrams routed to an interface that are larger than
its MTU are each split into two or more fragments. Each fragment
has its own IP header and is handled by the network as if it were
a distinct IP datagram, but when it arrives at the destination it
is held by the IP layer until all of the other fragments belong-
ing to the original datagram have arrived. Then they are reassem-
bled back into the complete, original IP datagram. The minimum
acceptable interface MTU is 28 bytes: 20 bytes for the IP
(fragment) header, plus 8 bytes of data.
There is no default MTU in net.exe; it must be explicitly speci-
fied for each interface as part of the attach command.
9.3.2. MSS
MSS (Maximum Segment Size) is a TCP-level parameter that limits
the amount of data that the remote TCP will send in a single TCP
packet. MSS values are exchanged in the SYN (connection request)
packets that open a TCP connection. In the net.exe implementation
of TCP, the MSS actually used by TCP is further reduced in order
May 28, 1991
- 43 -
to avoid fragmentation at the local IP interface. That is, the
local TCP asks IP for the MTU of the interface that will be used
to reach the destination. It then subtracts 40 from the MTU value
to allow for the overhead of the TCP and IP headers. If the
result is less than the MSS received from the remote TCP, it is
used instead.
The default value of MSS is 512 bytes.
9.3.3. Window
This is a TCP-level parameter that controls how much data the
local TCP will allow the remote TCP to send before it must stop
and wait for an acknowledgement. The actual window value used by
TCP when deciding how much more data to send is referred to as
the effective window. This is the smaller of two values: the
window advertised by the remote TCP minus the unacknowledged data
in flight, and the congestion window, an automatically computed
time-varying estimate of how much data the network can handle.
The default value of Window is 2048 bytes.
9.4. Discussion
9.4.1. IP Fragmentation vs AX.25 Segmentation
IP-level fragmentation often makes it possible to interconnect
two dissimilar networks, but it is best avoided whenever possi-
ble. One reason is that when a single IP fragment is lost, all
other fragments belonging to the same datagram are effectively
also lost and the entire datagram must be retransmitted by the
source. Even without loss, fragments require the allocation of
temporary buffer memory at the destination, and it is never easy
to decide how long to wait for missing fragments before giving up
and discarding those that have already arrived. A reassembly
timer controls this process. In net.exe it is (re)initialized
with the ip rtimer parameter (default 30 seconds) whenever
progress is made in reassembling a datagram (i.e., a new fragment
is received). It is not necessary that all of the fragments
belonging to a datagram arrive within a single timeout interval,
only that the interval between fragments be less than the time-
out.
Most subnetworks that carry IP have MTUs of 576 bytes or more, so
interconnecting them with subnetworks having smaller values can
result in considerable fragmentation. For this reason, IP imple-
mentors working with links or subnets having unusually small
packet size limits are encouraged to use transparent fragmenta-
tion, that is, to devise schemes to break up large IP datagrams
into a sequence of link or subnet frames that are immediately
reassembled on the other end of the link or subnet into the orig-
inal, whole IP datagram without the use of IP-level fragmenta-
tion. Such a scheme is provided in AX.25 Version 2.1. It can
break a large IP or NET/ROM datagram into a series of paclen-
sized AX.25 segments (not to be confused with TCP segments), one
per AX.25 I-frame, for transmission and reassemble them into a
single datagram at the other end of the link before handing it up
to the IP or NET/ROM module. Unfortunately, the segmentation
procedure is a new feature in AX.25 and is not yet widely
May 28, 1991
- 44 -
implemented; in fact, net.exe is so far the only known implemen-
tation. This creates some interoperability problems between
net.exe and non-net.exe nodes, in particular, standard NET/ROM
nodes being used to carry IP datagrams. This problem is discussed
further in the section on setting the MTU.
9.4.2. Setting paclen and bufsize
The more data you put into an AX.25 I frame, the smaller the
AX.25 headers are in relation to the total frame size. In other
words, by increasing paclen, you lower the AX.25 protocol over-
head. Also, large data packets reduce the overhead of keying up a
transmitter, and this can be an important factor with higher
speed modems. On the other hand, large frames make bigger targets
for noise and interference. Each link has an optimum value of
paclen that is best discovered by experiment.
Another thing to remember when setting paclen is that the AX.25
version 2.0 specification limits it to 256 bytes. Although
net.exe can handle much larger values, some other AX.25 implemen-
tations (including digipeaters) cannot and this may cause inter-
operability problems. Even net.exe may have trouble with certain
KISS TNCs because of fixed-size buffers. The original KISS TNC
code for the TNC-2 by K3MC can handle frames limited in size only
by the RAM in the TNC, but some other KISS TNCs cannot.
Net.exe's built-in HDLC drivers (SCC, PC-100, DRSI, etc) allocate
receive buffers according to the maximum expected frame size, so
it is important that these devices be configured with the correct
bufsize. To do this, you must know the size of the largest possi-
ble frame that can be received. The paclen parameter controls
only the size of the data field in an I-frame and not the total
size of the frame as it appears on the air. The AX.25 spec allows
up to 8 digipeaters, so the largest possible frame is (paclen +
72) bytes. So you should make bufsize at least this large.
Another important consideration is that the more recent versions
of NOS improve interrupt response by maintaining a special pool
of buffers for use by the receive routines. These buffers are
configured by the memory nibufs and memory ibufsize commands.
ibufsize defaults to 2048 bytes. The setting of ibufsize limits
bufsize; in fact, attempting to set a larger value may cause the
driver not to work at all. This situation can be detected by run-
ning the memory status command and looking for a non-zero count
of Ibuffail events, although these events can also occur occa-
sionally during normal operation.
One of the drawbacks of AX.25 that there is no way for one sta-
tion to tell another how large a packet it is willing to accept.
This requires the stations sharing a channel to agree beforehand
on a maximum packet size. TCP is different, as we shall see.
9.4.3. Setting Maxframe
For best performance on a half-duplex radio channel, maxframe
should always be set to 1. The reasons are explained in the paper
Link Level Protocols Revisited by Brian Lloyd and Phil Karn,
which appeared in the proceedings of the ARRL 5th Computer Net-
working Conference in 1986.
May 28, 1991
- 45 -
9.4.4. Setting MTU
TCP/IP header overhead considerations similar to those of the
AX.25 layer when setting paclen apply when choosing an MTU. How-
ever, certain subnetwork types supported by net.exe have well-
established MTUs, and these should always be used unless you know
what you're doing: 1500 bytes for Ethernet, and 508 bytes for
ARCNET. The MTU for PPP is automatically negotiated, and
defaults to 1500. Other subnet types, including SLIP and AX.25,
are not as well standardized.
SLIP has no official MTU, but the most common implementation (for
BSD UNIX) uses an MTU of 1006 bytes. Although net.exe has no
hard wired limit on the size of a received SLIP frame, this is
not true for other systems. Interoperability problems may there-
fore result if larger MTUs are used in net.exe.
Choosing an MTU for an AX.25 interface is more complex. When the
interface operates in datagram (UI-frame) mode, the paclen param-
eter does not apply. The MTU effectively becomes the paclen of
the link. However, as mentioned earlier, large packets sent on
AX.25 connections are automatically segmented into I-frames no
larger than paclen bytes. Unfortunately, as also mentioned ear-
lier, net.exe is so far the only known implementation of the new
AX.25 segmentation procedure. This is fine as long as all of the
NET/ROM nodes along a path are running net.exe, but since the
main reason net.exe supports NET/ROM is to allow use of existing
NET/ROM networks, this is unlikely.
So it is usually important to avoid AX.25 segmentation when run-
ning IP over NET/ROM. The way to do this is to make sure that
packets larger than paclen are never handed to AX.25. A NET/ROM
transport header is 5 bytes long and a NET/ROM network header
takes 15 bytes, so 20 bytes must be added to the size of an IP
datagram when figuring the size of the AX.25 I-frame data field.
If paclen is 256, this leaves 236 bytes for the IP datagram. This
is the default MTU of the netrom pseudo-interface, so as long as
paclen is at least 256 bytes, AX.25 segmentation can't happen.
But if smaller values of paclen are used, the netrom MTU must
also be reduced with the ifconfig command.
On the other hand, if you're running IP directly on top of AX.25,
chances are all of the nodes are running net.exe and support
AX.25 segmentation. In this case there is no reason not to use a
larger MTU and let AX.25 segmentation do its thing. If you choose
an MTU on the order of 1000-1500 bytes, you can largely avoid IP-
level fragmentation and reduce TCP/IP-level header overhead on
file transfers to a very low level. And you are still free to
pick whatever paclen value is appropriate for the link.
9.4.5. Setting MSS
The setting of this TCP-level parameter is somewhat less critical
than the IP and AX.25 level parameters already discussed, mainly
because it is automatically lowered according to the MTU of the
local interface when a connection is created. Although this is,
strictly speaking, a protocol layering violation (TCP is not sup-
posed to have any knowledge of the workings of lower layers) this
technique does work well in practice. However, it can be fooled;
for example, if a routing change occurs after the connection has
May 28, 1991
- 46 -
been opened and the new local interface has a smaller MTU than
the previous one, IP fragmentation may occur in the local system.
The only drawback to setting a large MSS is that it might cause
avoidable fragmentation at some other point within the network
path if it includes a "bottleneck" subnet with an MTU smaller
than that of the local interface. (Unfortunately, there is
presently no way to know when this is the case. There is ongoing
work within the Internet Engineering Task Force on a "MTU Discov-
ery" procedure to determine the largest datagram that may be sent
over a given path without fragmentation, but it is not yet com-
plete.) Also, since the MSS you specify is sent to the remote
system, and not all other TCPs do the MSS-lowering procedure yet,
this might cause the remote system to generate IP fragments
unnecessarily.
On the other hand, a too-small MSS can result in a considerable
performance loss, especially when operating over fast LANs and
networks that can handle larger packets. So the best value for
MSS is probably 40 less than the largest MTU on your system, with
the 40-byte margin allowing for the TCP and IP headers. For exam-
ple, if you have a SLIP interface with a 1006 byte MTU and an
Ethernet interface with a 1500 byte MTU, set MSS to 1460 bytes.
This allows you to receive maximum-sized Ethernet packets, assum-
ing the path to your system does not have any bottleneck subnets
with smaller MTUs.
9.4.6. Setting Window
A sliding window protocol like TCP cannot transfer more than one
window's worth of data per round trip time interval. So this TCP-
level parameter controls the ability of the remote TCP to keep a
long "pipe" full. That is, when operating over a path with many
hops, offering a large TCP window will help keep all those hops
busy when you're receiving data. On the other hand, offering too
large a window can congest the network if it cannot buffer all
that data. Fortunately, new algorithms for dynamic controlling
the effective TCP flow control window have been developed over
the past few years and are now widely deployed. Net.exe includes
them, and you can watch them in action with the tcp status <tcb>
or socket <sockno> commands. Look at the cwind (congestion win-
dow) value.
In most cases it is safe to set the TCP window to a small integer
multiple of the MSS (eg. 4 times), or larger if necessary to
fully utilize a high bandwidth*delay product path. One thing to
keep in mind, however, is that advertising a certain TCP window
value declares that the system has that much buffer space avail-
able for incoming data. Net.exe does not actually preallocate
this space; it keeps it in a common pool and may well "overbook"
it, exploiting the fact that many TCP connections are idle for
long periods and gambling that most applications will read incom-
ing data from an active connection as soon as it arrives, thereby
quickly freeing the buffer memory. However, it is possible to
run net.exe out of memory if excessive TCP window sizes are
advertised and either the applications go to sleep indefinitely
(eg. suspended Telnet sessions) or a lot of out-of-sequence data
arrives. It is wise to keep an eye on the amount of available
May 28, 1991
- 47 -
memory and to decrease the TCP window size (or limit the number
of simultaneous connections) if it gets too low.
Depending on the channel access method and link level protocol,
the use of a window setting that exceeds the MSS may cause an
increase in channel collisions. In particular, collisions between
data packets and returning acknowledgements during a bulk file
transfer may become common. Although this is, strictly speaking,
not TCP's fault, it is possible to work around the problem at the
TCP level by decreasing the window so that the protocol operates
in stop-and-wait mode. This is done by making the window value
equal to the MSS.
9.5. Summary
In most cases, the default values provided by net.exe for each of
these parameters will work correctly and give reasonable perfor-
mance. Only in special circumstances such as operation over a
very poor link or experimentation with high speed modems should
it be necessary to change them.
10. Mail Forwarding
10.1. Intended audience
This section is intended for the NOS system operator desiring to
enable the forwarding of mail to other systems. They are NOT
intended as a user guide for the mail capabilities of NOS.
10.2. Background
This section of the NOS docs deals with the intricacies of mail
forwarding. You should read and understand this documentation
thoroughly before attempting to forward mail through your NOS box
to the AX.25 BBS world, otherwise you might grossly misconfigure
your system and be the unhappy recipient of flames from BBS
sysops.
This section does NOT deal with the minutae of the mailbox and
its various commands; it assumes that you understand concepts
such as user areas (both public and private) and how to list and
send mail. If you need help with these, please look elsewhere in
the NOS docs.
Apart from the usual domain.txt and other files necessary for
ordinary functionality of NOS, three files are important in the
mail forwarding process. These are: /spool/forward.bbs, /alias
and /spool/rewrite. The contents of these will now be addressed
individually.
10.3. /spool/forward.bbs
This file describes the actions taken by NOS in forwarding to
AX.25 BBSes. The file contains a series of forwarding records,
each record being separated by a line containing two or more
hyphens. The template for a forwarding record is:
BBS callsign
Connection route
Connection commands <zero or more lines>
List of areas to be forwarded <one per line>
May 28, 1991
- 48 -
------------ <end of record>
10.4. BBS callsign
This is simply the ordinary call of the remote BBS. A typical
(but not random!) entry might be simply the line:
sm0rgv
The callsign may be followed, on the same line, by a comma sepa-
rated list of valid intervals when forwarding is to take place.
Each valid interval is a four digit number: the first two digits
are the beginning hour of the valid interval, the last two digits
are the final hour of the valid interval. For example, if the
first line of a forwarding record looks like:
sm0rgv 0006,1414
then forwarding to sm0rgv will take place only during hours num-
bered 00, 01, 02, 03, 04, 05, 06 and 14. Ticks of the mbox timer
outside of these times will not cause mail to be forwarded to
sm0rgv. The default interval for forwarding is 0023.
10.5. Connection route
This is the method by which communication is to be established
with the remote BBS. The first token on the line is the type of
protocol to be used. This is one of ax25, netrom or tcp. Follow-
ing this is whatever further information the chosen protocol
requires to make the connection. An example connection route for
a simple ax25 connection on interface ax0 is:
ax25 ax0 g3dlh
10.6. Connection commands
Connection commands may, optionally, follow the connection route.
These take the form of a full stop (period), followed by the com-
mand which will be transmitted once the connection defined in the
first line of the connection route is established.
For example, suppose that we wish to establish a netrom connec-
tion with sm0rgv-2, through the netrom node #sth67. Then the con-
nection route and connection command portion of the record would
look like:
netrom #sth67
.c sm0rgv-2 [ Please note that the full stop would be placed at
the beginning of the line; I have placed it here
indented by one column simply so that gateways
which handle this message do not complain at
having a line beginning with a full stop; this
convention is followed throughout this documentation]
If the station is reached through digipeating, then the digi-
peater callsigns should be in the ax25 route to the destination
callsign. That is, if you wish to forward traffic to w0ljf,
May 28, 1991
- 49 -
using k2na as a digipeater, then you should have the line:
ax25 route add w0ljf k2na
in your autoexec file.
10.7. List of areas to be forwarded
This is a list, one per line, of entries in the /spool/mail
directory which will be forwarded to the remote BBS. An entry of
the form:
callsign
will cause the file /spool/mail/callsign.txt to be scanned for
unread messages. Any such messages are sent to the remote BBS and
deleted from the file.
One can also forward user areas using this mechanism. To do this,
simply place a line containing the name of the area in the
record. So, to forward amsat bulletins to the BBS, one would have
a line:
amsat
This will search the /spool/mail/amsat.txt file; any messages
contained therein which have not been forwarded to the BBS in
question will be forwarded. They will NOT be deleted. The deter-
mining factor as to whether or not entries are deleted is that if
the filename is present in the /spool/areas file, then there is
NO deletion, otherwise there is.
Please note that ONLY FILES IN /spool/mail are checked. In par-
ticular, the outbound SMTP mail queue is NOT checked.
10.8. Changing the recipient address
Normally, NOS uses the information in the To: header line to
determine the parameters used by the "S" command during BBS for-
warding. As the To: header is unchanged by all /alias and
/spool/rewrite machinations, the mail will be sent to the BBS
addressed precisely as the originator of the message typed it.
Occasionally, one might want to change this behaviour. In this
case, a line of the form:
area new_address
in the list of areas to be forwarded will replace the originally
typed destination with the string new_address instead.
11. /alias
The alias file is used to map LOCAL names to other names, which
may be either local or remote; additionally, from a single input
message, the alias file permits one to produce multiple output
messages. Thus, typical uses for the /alias file are: converting
May 28, 1991
- 50 -
one local name to another, converting a local name to a remote
name, and exploding a mail message so that it is passed on to
several recipients.
The format of a record in the alias file is very simple:
aliasname recipient1 recipient2 recipient3
<tab> or <SP> recipient4 ... recipientN
There is no separation between records in the /alias file other
than a newline.
The aliasname is a local username; that is, it does not contain
an "@" symbol. When the alias file is processed, if the destina-
tion of the message matches precisely the aliasname, then the
mail is redirected to ALL of the alieased recipients.
Scanning of the /alias file is performed by the SMTP server. The
SMTP timer (which controls the SMTP client) is kicked whenever
the mailbox or SMTP server queues something for delivery by SMTP.
Mail transport within a single NOS system is performed through
the SMTP client/server mechanism. The result of these facts is
that as soon as a piece of mail is entered to the mailbox, the
SMTP client is kicked and attempts to deliver the mail (which has
already been scanned by the rewrite mechanism - see below). If
the mail is local to the NOS system (i.e. no "@" sign in the
address), then the /alias file will be scanned and the name map-
pings take place.
A few lines in the /alias file might look something like:
bdale bdale@n3eua
local fred@k0yum bdale@n3eua bill@ai0c.co.usa.na
n5op@n5op jim@k0jtz n0esg@n0esg
g4bki g4bki@gb7bil._2712.gbr.eu
The system must know how to deliver traffic to each of the indi-
vidual addresses in the style in which they are entered in the
/alias file. If the system does not know how to deliver one of
the new addresses, then it will send it to the SMTP gateway sta-
tion defined by the 'smtp gateway' command.
Note that it is reasonable, and sometimes desireable, to have
alias records of the form:
area area dest1 dest2 ...
As the /alias file is scanned only once (see below), this does
not result in an infinite recursion.
12. /spool/rewrite
The rewrite file is used to perform a one-to-one mapping between
destination addresses as received by NOS and destination
May 28, 1991
- 51 -
addresses as actually used by NOS. Each record within the rewrite
file comprises a single line, containing either two or three
entries separated by spaces. The first field is the template
field; if a destination address matches the template, it is
replaced by the second field. The third field, which is optional,
is the single letter "r", which, if present, tells NOS to rescan
the rewrite file, using the new destination address to attempt to
match against the templates.
A template may contain asterisks. These stand for a match of any
number of characters (including zero). In the second field, the
character "$", followed by a single digit in the range 1 to 9,
represents the string that matched the respective asterisk in the
template. By way of example, suppose that there is a line in the
rewrite file which looks like:
*@* $1%$2@g1emm.ampr.org
Then, any traffic reaching the system through the mailbox or the
SMTP server, but which is supposed to go to a remote system, will
be redirected to go through g1emm.ampr.org. Suppose that a user
logs on, and sends a message to n0gbe@nq0i. Then the rewrite file
attempts to match "n0gbe@nq0i" against the entry *@*. It matches,
and assignes $1 the value n0gbe, and $2 the value nq0i. The mail
file as written to the disk will no longer be to n0gbe@nq0i, but,
rather, to n0gbe%nq0i@g1emm.ampr.org. [The nomenclature sta-
tion1%station2@station3 means the final destination is sta-
tion1@station2, and this traffic is to be routed through the
gateway station3.]
As soon as a template match is found, the conversion is performed
and scanning is stopped, unless the third "r" field is present,
in which case scanning restarts from the top of the file.
N.B. It is a good idea to have a line of the form:
*@*.ampr.org $1@$2.ampr.org
at the beginning of your rewrite file. This will cause all ampr-
net traffic to be caught early in the rewrite scan, and no fur-
ther scanning (and, hence, no unexpected substitutions) will take
place.
12.1. Scanning procedure
The two files which are used to determine the disposition of
traffic are scanned under slightly different circumstances. Note
that neither the /alias nor the /spool/rewrite scan makes any
actual changes to the contents of the traffic. In particular, the
To: field remains exactly as it was first entered into the sys-
tem.
There are four possible entry routes for traffic into the system:
SMTP, through the mailbox by a user, through the mailbox by a
BBS, and via an external program (like BM) or creation of the
May 28, 1991
- 52 -
files manually. NOS determines if a piece of traffic was entered
into the system by a BBS by looking for a BBS system ID (like the
"[NET-H$]" block issued by NOS) on the incoming connection prior
to messages being uploaded.
12.2. Traffic received by SMTP server
1. The rewrite file is scanned and any changes applied (unless
the traffic was recieved through the local mailbox; in that case,
this step does not occur);
2. If the traffic appears to be local then the alias file is
scanned and any changes or explosions applied.
3. Any copies local to the system are delivered; copies for
remote delivery are placed in the SMTP queue.
12.3. Traffic received by mailbox from user
1. The rewrite file is scanned and any changes applied;
2. The traffic is passed to the SMTP client.
12.4. Traffic received by mailbox from BBS
1. The rewrite file is scanned and any changes applied;
2. The traffic is passed to the SMTP client.
12.5. Traffic entered by external mechanism
1. No scanning occurs;
2. The traffic is passed to the SMTP client.
12.6. Headers
Appropriate RFC-822 headers are added to all incoming traffic.
Traffic entering through the mailbox recieves a full complement
of RFC-822 headers; traffic coming through the SMTP server has
only a "Received:" header applied. On forwarding to a BBS, if an
item of traffic contains BBS R: headers, the RFC-822 header is
converted to an appropriate R: line at the time that NOS forwards
the message. (This change only occurs for BBS forwarding; for-
warding by SMTP retains the RFC-822 headers.)
12.7. Bulletin Identifiers (BIDs)
The AX.25 BBS system has evolved a reasonably efficient way of
reducing overhead when forwarding bulletins. When a bulletin is
originated on a BBS, it is given a unique bulletin identifier
(BID). This BID should (theoretically) travel with the bulletin,
and should never be changed during the distribution of the bul-
letin. Each system keeps track of all received BIDs. If a for-
warding station wishes to forward a bulletin to a BBS, then the
receiving station checks its local list of known BIDs and informs
the transmitting station if it already posesses the bulletin in
question. The NOS mailbox conforms to this protocol. Received
BIDs are stored in the file /spool/history, and are encoded in
the Message-ID: header line of the message by NOS. Messages for-
warded from areas listed in the /areas file will have their BID
(re)generated from the Message-ID: line. Note that ALL messages
from public areas are forwarded with a BID, whether or not the
message was produced with the "SB" command. Like other BBSes, NOS
will inform a transmitting station not to transmit a bulletin if
May 28, 1991
- 53 -
it is one that NOS already has locally; likewise, it understands
similar messages from other stations to which it tries to for-
ward.
Note that the BID mechanism is not a part of the SMTP world. If
you are forwarding bulletins through SMTP, there is no mechanism
by which the receiving station can reject the attempted delivery
of a bulletin, even if it already exists on the recipient system.
(Note that a possible workaround is to deliver bulletins to
TCP/IP stations using TCP instead of SMTP. Alternatively, one
could use NNTP, as NNTP commands utilise the Message-ID: line,
from which the BID is derived.) The BID is preserved no matter
which mechanism is used to deliver the bulletin.
12.8. Traffic in practice
Now, the big question is, how does one set up these various files
to perform intelligent manipulation of mail? A number of examples
follow. Note that, often, there is more than one way to accom-
plish an objective. The following are merely examples (and not
necessarily the most efficient method possible for any given
case). The format used will be:
typed destination -> intended destination
followed by the necessary entries in the alias (/alias), rewrite
(/spool/rewrite) and forwarding (/spool/forward.bbs) files.
12.9. Using familiar names - SMTP destination
bdale -> bdale@n3eua.ampr.org
alias:
bdale bdale@n3eua.ampr.org
rewrite:
forward:
12.10. Exploding local mail
sysops -> nq0i, n5op@n5op.ampr.org
alias:
sysops nq0i n5op@n5op@ampr.org
rewrite:
forward:
12.11. Using familiar names - BBS forwarding
g4bki -> g4bki@gb7bil._2712.gbr.eu, to be forwarded by ai0c
alias:
rewrite:
May 28, 1991
- 54 -
forward:
ai0c
ax25 ax1 ai0c
g4bki g4bki@gb7bil._2712.gbr.eu
ai0c
12.12. Handling incoming bulletins by subject
tcpip@* -> nq0i, tcpip, bdale@n3eua.ampr.org, ai0c@ai0c [a BBS]
alias:
tcpip nq0i tcpip bdale@n3eua.ampr.org ai0c
rewrite:
tcpip@* tcpip
forward:
ai0c
ax25 ai0c
ai0c
Let's walk through the above example. An incoming item comes in
addressed to TCPIP@ALLUS. A scan is made through the rewrite
file, and a match is found. The item is redirected to tcpip. The
alias file is scanned; a total of four copies of the item exist
after this, three in local areas tcpip, nq0i and ai0c, and one on
the SMTP queue (for bdale@n3eua.ampr.org). When the mailbox timer
next ticks, the mail in the local ai0c area will be forwarded on
the ax1 interface to ai0c.
12.13. Routing based on Hierarchical addressing
Wyoming -> KE7VS (SMTP)
Nebraska -> AG0N (BBS over the NETROM, NETROM ID WNBBS)
Europe -> W0LJF (BBS over AX.25)
alias:
rewrite:
*.noam $1.na r
*.us $1.usa.na r
*.usa $1.usa.na r
*.ne $1.ne.usa.na r
*.wy $1.wy.usa.na r
*@*.*.wy.usa.na $1%$2.$3.wy.usa.na@ke7vs
*@*.wy.usa.na $1%$2.wy.usa.na@ke7vs
*.ne.usa.na ag0n
*.eu w0ljf
forward:
May 28, 1991
- 55 -
ag0n
netrom ax0 wnbbs
ag0n
----------
w0ljf
ax25 ax1 w0ljf
w0ljf
----------
Why is the example rewrite file apparently so complicated? This
is to handle poorly constructed hierarchical addresses in a rea-
sonable way. A full U.S. hierarchical address has the form:
callsign@BBS.#localid.state.usa.na. Many states have no #localid
field. In the example rewrite file above, the first three lines
convert non-standard, but frequently used, U.S. designators to
the more standard format. It is common for users not to use a
full hierarchical address if the destination is relatively local.
For eample, a user might easily use only .wy instead of the full
grouping of two lines handles this problem. Note the third, "r",
field in all the entries so far.
The remainder of the file handles properly formatted hierarchical
addresses. The two Wyoming entries handle the cases with and
without a #localid field. Differentiation between these cases is
not necessary for BBS forwarding.
12.14. General bulletin handling
The details of bulletin handling will vary somewhat from place to
place, as there are several distinct styles of bulletin handling
currently in use in the AX.25 BBS world. In general, it is neces-
sary to arrange one's system so that it accepts bulletins from
BBSes, forwards them to one or more stations, and also handles
intelligently bulletins input by users into NOS.
Suppose that we sish to handle bulletins @JUNK. We are to deposit
them locally in the junk area, and also forward to BBS g4bki. We
also know that we generally receive @JUNK bulletins from g4amj, a
local BBS which handles much bulletin traffic.
alias:
rewrite:
*@junk junk
forward:
g4bki
ax25 ax1 g4bki
g4bki
junk
----------
g4amj
ax25 ax1 g4amj
g4amj
junk
----------
May 28, 1991
- 56 -
All incoming @JUNK traffic is written to the junk area (which
should be an explicit entry in the /spool/areas file). Each tick
of the mailbox timer, NOS scans the junk area for traffic not
forwarded to g4bki or g4amj and attempts to deliver unforwarded
bulletins. Usually, g4amj will respond with a "Have it" message
and the bulletin will not be forwarded. Any bulletins @JUNK
deposited locally by users will automatically be sent to both
g4bki and g4amj.
13. Questions and Answers
Q. Under what circumstances does NOS request reverse forwarding
from a BBS?
A. NOS requests a reverse forward after completing any forwards
of its own to the BBS. If no traffic was queued for a given BBS,
then no connection is attempted, so no reverse forward request is
issued.
Q. What kinds of message types does the NOS mbox support?
A. Basically, NOS supports all two letter commands starting with
an "S". If the mailbox has not received an SID banner (the "[NET-
H$]") from a connected station, then an SF command will send a
followup to the address specified on the command line. The SR
command will send a reply to the current message. One can also
issue the command "SR <number>", where <number> is the number of
the message to which you want to generate a reply. All other
variations cause an X-BBS-Msg-Type: header to be added to the
message. When a message with such a line is forwarded to a BBS,
it is sent to the BBS with the appropriate message type as the
second letter in the "S" command to the BBS.
If NOS has received a valid SID, then ALL S commands are handled
by the X-BBS-Msg-Type: mechanism outlined above.
May 28, 1991
- 57 -
14. Logic map of the mailbox
============== AX.25 === NET/ROM === Ethernet === Loopback =================
| | | |
| | | |
+--------------+ +--------------+ +--------------+ +--------------+
| | | | | | | |
| Mailbox | | SMTP client | | SMTP server | | BBS Forward |
| | | | | | | |
+--------------+ +--------------+ +--------------+ +--------------+
| ^ | ^
| | | |
v | v |
+--------------+ +--------------+ +--------------+ +--------------+
| | | | | | | |
| Add RFC822 | | Use MX or A | | Add Received | | Add own R: |
| header suite | | type records | | line | +>| line |
| | | | | | | | |
+--------------+ +--------------+ +--------------+ | +--------------+
| ^ | | ^
| | | | |
v | v | |
+--------------+ +--------------+ +--------------+ | +--------------+
| | | | | | | | |
| Get Rewrite | | Use optional | | Apply Rewrite| | | Strip RFC822 |
| file address | | SMTP gateway | | file address | | | header suite |
| | | | | | | | |
+--------------+ +--------------+ +--------------+ | +--------------+
| ^ | | ^
| | | | | Yes
v | v | |
+--------------+ | +--------------+ | +--------------+
| | No | | | | | |
| Local addr? |-------+ | | Alias file | +-| Any R: lines?|
| | | | | | No | |
+--------------+ | | +--------------+ +--------------+
| | | | | | ^
| Yes | | | | | |
v | | v v v |
+--------------+ v | +--------------+ +--------------+
| | +--------------+ | | | |
| Apply Rewrite| | | No | Local |Yes | /spool/mail/ |
| file address |--->| SMTP queue |<---| address? |--->| directory |
| | | | | | | |
+--------------+ +--------------+ +--------------+ +--------------+
15. Credits
Several people have contributed to this manual. I would particu-
larly like to thank Bill Simpson and Michael Westerhof, KA9WSB,
for their significant editorial contributions to this document.
Deborah Swanberg wrote the original BOOTP documentation,. and
G4AMJ/NQ0I and SM0RGV contributed the section on mail forwarding.
Although I am the primary author of this software package, many
others have contributed substantial additions and refinements.
May 28, 1991
- 58 -
Here is a partial list; additions and corrections are welcome.
See the individual source code files for additional authorship
details.
15.1. ARCNET
Written by Russ Nelson of Clarkson University.
15.2. Autodialer
Bill Simpson substantially rewrote my original version and cre-
ated a much improved control file format.
15.3. Bootstrap Protocol (BOOTP)
Written by Deborah Swanberg of the University of Michigan.
15.4. Domain resolver
Bill Simpson substantially extended my original version, adding
record caching and automatic expiration.
15.5. DRSI driver
Written by Stu Phillips, N6TTO.
15.6. Eagle 8530 board driver
Written by Art Goldman, WA3CVG, and Richard Bisbey, NG6Q.
15.7. HAPN 8273 HDLC board driver
Written by Jon Bloom, KE3Z, with fixes by John Tanner, VK2ZXQ.
15.8. Hop Check utility
Written by Katie Stevens of UC Davis; enhancements by Bill Simp-
son.
15.9. Mailbox server & SMTP
My original, primitive SMTP server was vastly enhanced and
expanded by Bdale Garbee, N3EUA and Dave Trulli, NN2Z. Anders
Klemets, SM0RGV, wrote the first "mailbox" specifically for
AX.25; he then expanded it into a full-blown bulletin board sys-
tem and integrated it with the SMTP facilities.
15.10. NET/ROM
The original NET/ROM code was done by Dan Frank, W9NK. It was
ported to the NOS platform by Anders Klemets, SM0RGV.
15.11. Netnews Transfer Protocol (NNTP)
Written by Anders Klements, SM0RGV, with help from Bernie Roehl
and Gerard Van Der Grinten, PA0GRI.
15.12. Packet Drivers
Although not really part of this package, the Clarkson Packet
Driver Collection by Russ Nelson of Clarkson University has enor-
mously enhanced the utility of this package by allowing it to use
virtually every PC Ethernet controller board on the market.
May 28, 1991
- 59 -
15.13. PI 8530 DMA HDLC driver
Written by Dave Perry, VE3IFB.
15.14. Post Office Protocol (POP)
Originally authored by Mike Stockett, WA7DYX. Updates and modifi-
cations by Allen Gwinn, N5CKP, Gerard Van Der Grinten, PA0GRI,
and Mark Edwards, WA6SMN.
15.15. Point to Point Protocol (PPP)
Written by Katie Stevens of UC Davis, based on the original
implementation by Drew Perkins of CMU. Updated by Bill Simpson
and Glenn McGregor of the University of Michigan.
15.16. Routing Information Protocol (RIP)
Original (pre-NOS) version written by Al Broscious N3FCT.
15.17. SCC - Generic 8530 driver
Originally written for the old "NET" code by Rob Janssen, PE1CHL.
Ported to NOS by Ken Mitchum, KY3B.
15.18. Socket-level stream compression
Written by Anders Klemets, SM0RGV
15.19. TCP/IP Header Compression
Adapted from Van Jacobson's original BSD UNIX implementation by
Katie Stevens of UC Davis. Updated by Bill Simpson.
May 28, 1991
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