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Archive-name: linux/howto/ax25/part2
Last-modified: 23 Jun 96

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*** The `Linux AX25 HOWTO' is posted automatically by the
*** Linux HOWTO coordinator, Greg Hankins <gregh@sunsite.unc.edu>.  Please
*** direct any comments or questions about this HOWTO to the author,
*** Terry Dawson <terry@perf.no.itg.telecom.com.au>.

- --- BEGIN Linux AX25 HOWTO part 2/2 ---

     shell
        this is the login shell of any new users.

     associate
        this flag indicates whether outgoing AX.25 connections made by
        this user after they login will use their own callsign, or your
        stations callsign.

  14.5.  Configuring the pms

  The pms program is an implementation of a simple personal message
  system. It was originally written by Alan Cox. Dave Brown, N2RJT,
  <dcb@vectorbd.com> has taken on further development of it.  At present
  it is still very simple, supporting only the ability to send mail to
  the owner of the system and to obtain some limited system information
  but Dave is working to expand its capability to make it more useful.

  Configuring the pms program is still a little clumsy at the moment
  because it is new but bare with it while Dave works on it. The only
  difficult part is modifying the source code to support your local mail
  delivery agent and whether you use the ttylinkd program or the talk-
  ax25 program.

  After that is done there are a couple of simple files that you should
  create that give users some information about the system and then you
  need to add appropriate entries into the ax25d.conf file so that
  connected users are presented with the PMS.

  14.5.1.  Customising pms.c

  If you take a look at the pms.c file in the ax25-utils package you
  will see that there a few items that you can configure.  Perhaps the
  most important to configure is the one that allows you to specify what
  local mail delivery agent you use. In most installations the deliver
  program may well work, but in the minimal installation on my gateway
  machine I needed to modify the line that previously said:

  #define MAIL_DELIVERY_AGENT     "deliver %s"

  to:

  #define MAIL_DELIVERY_AGENT     "/bin/mail.local %s"

  There is no easy way of knowing what local delivery agent your machine
  is configured to use, so perhaps you could simply look for either of
  these files in the obvious places and choose whichever seems to be
  there.

  I also have the ttylinkd program installed, so I needed to modify the
  section relating to it. I keep my copy of the ttylinkd program in my
  /usr/sbin directory, so I modified the line that previously said:

  /* #define MY_TALK              "/usr/local/sbin/ttylinkd" */

  to:

  #define MY_TALK              "/usr/sbin/ttylinkd"

  If you use the talk-ax25 program then you would remove the /* and */
  from around that line instead.

  There is one last definition that might be useful to you, and that is
  if you have a default email gateway. This line is the line containing
  the string MY_GATEWAY. If you have an email gateway that you use, then
  you should remove the comments from this line and change the address
  to that of your gateway.

  14.5.2.  Create the /usr/local/pms/motd file.

  The /usr/local/pms/motd file contains the `message of the day' that
  users will be presented with after they connect and receive the usual
  BBS id header. The file is a simple text file, any text you include in
  this file will be sent to users.

  14.5.3.  Create the /usr/local/pms/info file.

  The /usr/local/pms/info file is also a simple text file in which you
  would put more detailed information about your station or
  configuration.  This file is presented to users in response to their
  issuing of the Info command from the PMS> prompt.

  14.5.4.  Associate AX.25 callsigns with system users.

  When a connected user sends mail to an AX.25 callsign, the pms expects
  that callsign to be mapped, or associated with a real system user on
  your machine.

  You make this association with the axparms command. An example looks
  like:

       # axparms -assoc vk2ktj terry

  This command associates that AX.25 callsign vk2ktj with the user terry
  on the machine, so any mail for vk2ktj on the pms will be sent to
  terry.

  Remember to put these associations into your rc file so that they are
  available each time your reboot.

  14.5.5.  Add the PMS to the /usr/local/etc/ax25d.conf file.

  Adding the pms to your ax25d.conf file is very simple.  There is one
  small thing you need to think about though. Dave has added command
  line arguments to the PMS to allow it to handle a number of different
  text end-of-line conventions. AX.25 and NetRom by convention expect
  the end-of-line to be carriage return, linefeed while the standard
  unix end-of-line is just newline. So, for example, if you wanted to
  add an entry that meant that the default action for a connection
  received on an AX.25 port is to start the PMS then you would add a
  line that looked something like:

       default  1  10 5 100 5   0    root  /usr/local/bin/pms pms -a -o vk2ktj

  This simply runs the pms program, telling it that it is an AX.25
  connection it is connected to and that the PMS owner is vk2ktj.  Check
  the man page for what you should specify for other connection methods.
  14.5.6.  Test the PMS.

  To test the PMS, you can try the following command from the command
  line:

  # /usr/local/bin/pms -u vk2ktj -o vk2ktj

  Substitute your own callsign for mine and this will run the pms,
  telling it that it is to use the unix end-of-line convention, and that
  user logging in is vk2ktj. You can do all the things connected users
  can.

  Additionally you might try getting some other node to connect to you
  to confirm that your ax25d.conf configuration works.

  15.  HOWTO link NOS and the Linux kernel networking software

  Many people like to run some version of NOS under Linux because it has
  all of the features and facilities they are used to. Most of those
  people would also like to have the NOS running on their machine
  capable of talking to the Linux kernel so that they can offer some of
  the linux capabilities to radio users.

  15.1.  Linking NOS and Linux using a pipe device

  Brandon S. Allbery, KF8NH, contributed the following information to
  explain how to interconnect the NOS running on a Linux machine with
  the kernel code using the Linux pipe device.

  Since both Linux and NOS support the slip protocol it is possible to
  link the two together by creating a slip link. You could do this by
  using two serial ports with a loopback cable between them, but this
  would be slow and costly. Linux provides a feature that many other
  Unix-like operating systems provide called `pipes'. These are special
  pseudo devices that look like a standard tty device to software but in
  fact loopback to another pipe device. To use these pipes the first
  program must open the master end of the pipe, and the open then the
  second program can open the slave end of the pipe. When both ends are
  open the programs can communicate with each other simply by writing
  characters to the pipes in the way they would if they were terminal
  devices.

  To use this feature to connect the Linux Kernel and a copy of NOS, or
  some other program you first must choose a pipe device to use. You can
  find one by looking in your /dev directory. The master end of the
  pipes are named: ptyp[1-f] and the slave end of the pipes are known
  as: ttyp[1-f]. Remember they come in pairs, so if you select
  /dev/ptypf as your master end then you must use /dev/ttypf as the
  slave end.

  Once you have chosen a pipe device pair to use you should allocate the
  master end to you linux kernel and the slave end to the NOS program,
  as the Linux kernel starts first and the master end of the pipe must
  be opened first.  You must also remember that your Linux kernel must
  have a different IP address to your NOS, so you will need to allocate
  a unique address for it if you haven't already.

  You configure the pipe just as if it were a serial device, so to
  create the slip link from your linux kernel you can use commands
  similar to the following:

  # /sbin/slattach -s 38400 -p slip /dev/ptypf &
  # /sbin/ifconfig sl0 broadcast 44.255.255.255 pointopoint 44.70.248.67 /
          mtu 1536 44.70.4.88
  # /sbin/route add 44.70.248.67 sl0
  # /sbin/route add -net 44.0.0.0 gw 44.70.248.67

  In this example the Linux kernel has been given IP address 44.70.4.88
  and the NOS program is using IP address 44.70.248.67. The route
  command in the last line simply tells your linux kernel to route all
  datagrams for the amprnet via the slip link created by the slattach
  command. Normally you would put these commands into your
  /etc/rc.d/rc.inet2 file after all your other network configuration is
  complete so that the slip link is created automatically when you
  reboot.  Note: there is no advantage in using cslip instead of slip as
  it actually reduces performance because the link is only a virtual one
  and occurs fast enough that having to compress the headers first takes
  longer than transmitting the uncompressed datagram.

  To configure the NOS end of the link you could try the following:

       # you can call the interface anything you want; I use "linux" for convenience.
       attach asy ttypf - slip linux 1024 1024 38400
       route addprivate 44.70.4.88 linux

  These commands will create a slip port named `linux' via the slave end
  of the pipe device pair to your linux kernel, and a route to it to
  make it work. When you have started NOS you should be able to ping and
  telnet to your NOS from your Linux machine and vice versa. If not,
  double check that you have made no mistakes especially that you have
  the addresses configured properly and have the pipe devices around the
  right way.

  16.  Some sample configurations.

  Following are examples of the most common types of configurations.
  These are guides only as there are as many ways of configuring your
  network as there are networks to configure, but they may give you a
  start.

  16.1.  Small Ethernet LAN with Linux as a router to Radio LAN

  Many of you may have small local area networks at home and want to
  connect the machines on that network to your local radio LAN. This is
  the type of configuration I use at home. I arranged to have a suitable
  block of addresses allocated to me that I could capture in a single
  route for convenience and I use these on my Ethernet LAN. Your local
  IP coordinator will assist you in doing this if you want to try it as
  well. The addresses for the Ethernet LAN form a subset of the radio
  LAN addresses. The following configuration is the actual one for my
  linux router on my network at home:

                                            .      .   .    .    . .
    ---                                .
     | Network       /---------\     .    Network
     | 44.136.8.96/29|         |    .     44.136.8/24        \ | /
     |               | Linux   |   .                          \|/
     |               |         |  .                            |
     |          eth0 | Router  |  .  /-----\    /----------\   |
     |---------------|         |-----| TNC |----| Radio    |---/
     |   44.136.8.97 |  and    |  .  \-----/    \----------/
     |               |         | sl0
     |               | Server  | 44.136.8.5
     |               |         |    .
     |               |         |     .
     |               \_________/       .
    ---                                     .      .   .    .    . .

       #!/bin/sh
       # /etc/rc.net
       # This configuration provides one KISS based AX.25 port and one
       # Ethernet device.

       echo "/etc/rc.net"
       echo "  Configuring:"

       echo -n "    loopback:"
       /sbin/ifconfig lo 127.0.0.1
       /sbin/route add 127.0.0.1
       echo " done."

       echo -n "    ethernet:"
       /sbin/ifconfig eth0 44.136.8.97 netmask 255.255.255.248 \
                       broadcast 44.136.8.103 up
       /sbin/route add 44.136.8.97 eth0
       /sbin/route add -net 44.136.8.96 netmask 255.255.255.248 eth0
       echo " done."

       echo -n "    AX.25: "
       axattach -i 44.136.8.5 -m 512 /dev/ttyS1 4800
       ifconfig sl0 netmask 255.255.255.0 broadcast 44.136.8.255
       route add -host 44.136.8.5 sl0
       route add -net 44.136.8.0 window 1024 sl0

       echo -n "    Netrom: "
       nrattach -i 44.136.8.5 netrom

       echo "  Routing:"
       /sbin/route add default gw 44.136.8.68 window 1024 sl0
       echo "    default route."
       echo done.

       # end

  /usr/local/etc/axports

       # name  callsign        speed   paclen  window  description
       4800    VK2KTJ-0        4800    256     2       144.800 MHz

  /usr/local/etc/nrports

       # name  callsign        alias   paclen  description
       netrom  VK2KTJ-1        LINUX   235     Linux Switch Port

  /usr/local/etc/nrbroadcast

       # ax25_name     min_obs def_qual        worst_qual      verbose
       4800            1       120             10              1

  �  You must have IP_FORWARDING enabled in your kernel.

  �  The AX.25 configuration files are pretty much those used as
     examples in the earlier sections, refer to those where necessary.

  �  I've chosen to use an IP address for my radio port that is not
     within my home network block. I needn't have done so, I could have
     easily used 44.136.8.97 for that port too.

  �  44.136.8.68 is my local IPIP encapsulated gateway and hence is
     where I point my default route.

  �  Each of the machines on my Ethernet network have a route:

       route add -net 44.0.0.0 gw 44.136.8.97 window 512 mss 512 eth0

  The use of the mss and window parameters means that I can get optimum
  performance from both local Ethernet and radio based connections.

  �  I also run my sendmail, http, ftp and other daemons on the router
     machine so that it needs to be the only machine to provide others
     with facilities.

  �  The router machine is a lowly 386DX20 with a 20Mb harddrive and a
     very minimal linux configuration.

  16.2.  IPIP encapsulated gateway configuration.

  Linux is now very commonly used for tcp/ip encapsulated gateways
  around the world. The new tunnel driver supports multiple encapsulated
  routes and makes the older ipip daemon obsolete.

  A typical configuration would look similar to the following.

                                            .      .   .    .    . .
    ---                                .
     | Network       /---------\     .    Network
     | 154.27.3/24   |         |    .     44.136.16/24       \ | /
     |               | Linux   |   .                          \|/
     |               |         |  .                            |
     |          eth0 | IPIP    |  .  /-----\    /----------\   |
  ---|---------------|         |-----| TNC |----| Radio    |---/
     |   154.27.3.20 | Gateway |  .  \-----/    \----------/
     |               |         | sl0
     |               |         | 44.136.16.1
     |               |         |    .
     |               |         |     .
     |               \_________/       .
    ---                                     .      .   .    .    . .

  The configuration files of interest are:

       # /etc/rc.net
       # This file is a simple configuration that provides one KISS AX.25
       # radio port, one Ethernet device, and utilises the kernel tunnel driver
       # to perform the IPIP encapsulation/decapsulation
       #
       echo "/etc/rc.net"
       echo "  Configuring:"
       #
       echo -n "    loopback:"
       /sbin/ifconfig lo 127.0.0.1
       /sbin/route add 127.0.0.1
       echo " done."
       #
       echo -n "    ethernet:"
       /sbin/ifconfig eth0 154.27.3.20 netmask 255.255.255.0 \
                       broadcast 154.27.3.255 up
       /sbin/route add 154.27.3.20 eth0
       /sbin/route add -net 154.27.3.0 netmask 255.255.255.0 eth0
       echo " done."
       #
       echo -n "    AX.25: "
       axattach -i 44.136.16.1 -m 512 /dev/ttyS1 4800
       /sbin/ifconfig sl0 netmask 255.255.255.0 broadcast 44.136.16.255
       /sbin/route add -host 44.136.16.1 sl0
       /sbin/route add -net 44.136.16.0 netmask 255.255.255.0 window 1024 sl0
       #
       echo -n "    tunnel:"
       /sbin/ifconfig tunl0 44.136.16.1 mtu 512 up
       #
       echo done.
       #
       echo -n "Routing ... "
       source /etc/ipip.routes
       echo done.
       #
       # end.

  and:

       # /etc/ipip.routes
       # This file is generated using the munge script
       #
       /sbin/route add 44.134.8.0 netmask 255.255.255.0 tunl0 gw 134.43.26.1
       /sbin/route add 44.34.9.0 netmask 255.255.255.0 tunl0 gw 174.84.6.17
       /sbin/route add 44.13.28.0 netmask 255.255.255.0 tunl0 gw 212.37.126.3
          ...
          ...
          ...

  /usr/local/etc/axports

       # name  callsign        speed   paclen  window  description
       4800    VK2KTJ-0        4800    256     2       144.800 MHz

  Some points to note here are:

  �  The new tunnel driver uses the gw field in the routing table in
     place of the pointopoint parameter to specify the address of the
     remote IPIP gateway. This is why it now supports multiple routes
     per interface.

  �  You can configure two network devices with the same address.  In
     this example both the sl0 and the tunl0 devices have been
     configured with the IP address of the radio port. This is done so
     that the remote gateway sees the correct address from your gateway
     in encapsulated datagrams sent to it.

  �  The route commands used to specify the encapsulated routes can be
     automatically generated by a modified version of the munge script.
     This is included below. The route commands would then be written to
     a separate file and read in using the bash source /etc/ipip.routes
     command (assuming you called the file with the routing commands
     /etc/ipip.routes) as illustrated. The source file must be in the
     NOS route command format.

  �  Note the use of the window argument on the route command. Setting
     this parameter to an appropriate value improves the performance of
     your radio link.

  The new tunnel-munge script:

  #!/bin/sh
  #
  # From: Ron Atkinson <n8fow@hamgate.cc.wayne.edu>
  #
  #  This script is basically the 'munge' script written by Bdale N3EUA
  #  for the IPIP daemon and is modified by Ron Atkinson N8FOW. It's
  #  purpose is to convert a KA9Q NOS format gateways route file
  #  (usually called 'encap.txt') into a Linux routing table format
  #  for the IP tunnel driver.
  #
  #        Usage: Gateway file on stdin, Linux route format file on stdout.
  #               eg.  tunnel-munge < encap.txt > ampr-routes
  #
  # NOTE: Before you use this script be sure to check or change the
  #       following items:
  #
  #     1) Change the 'Local routes' and 'Misc user routes' sections
  #        to routes that apply to your own area (remove mine please!)
  #     2) On the fgrep line be sure to change the IP address to YOUR
  #        gateway Internet address. Failure to do so will cause serious
  #        routing loops.
  #     3) The default interface name is 'tunl0'. Make sure this is
  #        correct for your system.

  echo "#"
  echo "# IP tunnel route table built by $LOGNAME on `date`"
  echo "# by tunnel-munge script v960307."
  echo "#"
  echo "# Local routes"
  echo "route add -net 44.xxx.xxx.xxx netmask 255.mmm.mmm.mmm dev sl0"
  echo "#"
  echo "# Misc user routes"
  echo "#"
  echo "# remote routes"

  fgrep encap | grep "^route" | grep -v " XXX.XXX.XXX.XXX" | \
  awk '{
          split($3, s, "/")
          split(s[1], n,".")
          if      (n[1] == "")    n[1]="0"
          if      (n[2] == "")    n[2]="0"
          if      (n[3] == "")    n[3]="0"
          if      (n[4] == "")    n[4]="0"
          if      (s[2] == "1")   mask="128.0.0.0"
          else if (s[2] == "2")   mask="192.0.0.0"
          else if (s[2] == "3")   mask="224.0.0.0"
          else if (s[2] == "4")   mask="240.0.0.0"
          else if (s[2] == "5")   mask="248.0.0.0"
          else if (s[2] == "6")   mask="252.0.0.0"
          else if (s[2] == "7")   mask="254.0.0.0"
          else if (s[2] == "8")   mask="255.0.0.0"
          else if (s[2] == "9")   mask="255.128.0.0"
          else if (s[2] == "10")  mask="255.192.0.0"
          else if (s[2] == "11")  mask="255.224.0.0"
          else if (s[2] == "12")  mask="255.240.0.0"
          else if (s[2] == "13")  mask="255.248.0.0"
          else if (s[2] == "14")  mask="255.252.0.0"
          else if (s[2] == "15")  mask="255.254.0.0"
          else if (s[2] == "16")  mask="255.255.0.0"
          else if (s[2] == "17")  mask="255.255.128.0"
          else if (s[2] == "18")  mask="255.255.192.0"
          else if (s[2] == "19")  mask="255.255.224.0"
          else if (s[2] == "20")  mask="255.255.240.0"
          else if (s[2] == "21")  mask="255.255.248.0"
          else if (s[2] == "22")  mask="255.255.252.0"
          else if (s[2] == "23")  mask="255.255.254.0"
          else if (s[2] == "24")  mask="255.255.255.0"
          else if (s[2] == "25")  mask="255.255.255.128"
          else if (s[2] == "26")  mask="255.255.255.192"
          else if (s[2] == "27")  mask="255.255.255.224"
          else if (s[2] == "28")  mask="255.255.255.240"
          else if (s[2] == "29")  mask="255.255.255.248"
          else if (s[2] == "30")  mask="255.255.255.252"
          else if (s[2] == "31")  mask="255.255.255.254"
          else                    mask="255.255.255.255"

  if (mask == "255.255.255.255")
          printf "route add -host %s.%s.%s.%s gw %s dev tunl0\n"\
                  ,n[1],n[2],n[3],n[4],$5
  else
          printf "route add -net %s.%s.%s.%s gw %s netmask %s dev tunl0\n"\
                  ,n[1],n[2],n[3],n[4],$5,mask
   }'

  echo "#"
  echo "# default the rest of amprnet via mirrorshades.ucsd.edu"
  echo "route add -net 44.0.0.0 gw 128.54.16.18 netmask 255.0.0.0 dev tunl0"
  echo "#"
  echo "# the end"

  17.  Discussion relating to Amateur Radio and Linux.

  There are various places that discussion relating to Amateur Radio and
  Linux take place. They take place in the comp.os.linux.* newsgroups,
  they also take place on the HAMS list on vger.rutgers.edu. Other
  places where they are held include the tcp-group mailing list at
  ucsd.edu (the home of amateur radio tcp/ip discussions), and you might
  also try the #linpeople channel on the linuxnet irc network.

  To join the Linux linux-hams channel on the mail list server, send
  mail to:

       Majordomo@vger.rutgers.edu

  with the line:

       subscribe linux-hams

  in the message body. The subject line is ignored.

  To join the tcp-group send mail to:

       listserver@ucsd.edu

  with the line:
       subscribe tcp-group

  in the body of the text.

  Note: Please remember that the tcp-group is primarily for discussion
  of the use of advanced protocols, of which tcp/ip is one, in Amateur
  Radio. Linux specific questions should not ordinarily go there.

  18.  Copyright.

  The AX25-HOWTO, information on how to install and configure some of
  the more important packages providing AX25 support for Linux.
  Copyright (c) 1996 Terry Dawson.

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or (at
  your option) any later version.

  This program is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the:

  Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139,
  USA.


- --- END Linux AX25 HOWTO part 2/2 ---

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