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Archive-name: linux/howto/ax25/part1
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 1/2 ---

  Linux AX25-HOWTO, Amateur Radio.
  Terry Dawson, VK2KTJ, terry@perf.no.itg.telecom.com.au
  v1.1, 14 June 1996

  The Linux Operating System is perhaps the only operating system in the
  world that can boast native and standard support for the AX.25 packet
  radio protocol utilised by Amateur Radio Operators worldwide. This
  document aims to describe how to install and configure this support.

  1.  Introduction.

  This document was originally an appendix to the HAM-HOWTO, but grew
  too large to be reasonably managed in that fashion. This document
  describes how to install and configure the native AX.25 and NetRom
  support for Linux. A few typical configurations are described that
  could be used as models to work from.

  1.1.  Changes from the previous version

  Additions:
          Baycom support - ye gads!

  Corrections/Updates:
          Included SLIP support in kernel config - oops.
          2.0.0 kernel and ax25-tools update.
          Updated net-tools to 1.32-alpha version.
          Removed Jonathons `special' net-tools.
          A bit of shuffling about to make more sense.
          Updated the example configurations.
          A minor copyright ooops.

  1.2.  Other related documentation.

  There is a lot of related documentation. There are many documents that
  relate to Linux networking in more general ways and I strongly
  recommend you also read these as they will assist you in your efforts
  and provide you with stronger insight into other possible
  configurations.

  They are:

  The HAM-HOWTO <http://sunsite.unc.edu/mdw/HOWTO/HAM-HOWTO.html>

  the Net-2-HOWTO <http://sunsite.unc.edu/mdw/HOWTO/NET-2-HOWTO.html>

  the Ethernet-HOWTO <http://sunsite.unc.edu/mdw/HOWTO/Ethernet-
  HOWTO.html>

  the IPX-HOWTO <http://sunsite.unc.edu/mdw/HOWTO/IPX-HOWTO.html>

  and

  the Firewall-HOWTO <http://sunsite.unc.edu/mdw/HOWTO/Firewall-
  HOWTO.html>

  2.  Where to obtain new versions of this document.

  The best place to obtain the latest version of this document is from a
  Linux Documentation Project archive. The Linux Documentation Project
  runs a Web Server and this document appears there as The AX25-HOWTO
  <http://sunsite.unc.edu/mdw/HOWTO/AX25-HOWTO.html>. You can always
  contact me, but I pass new versions of the document directly to the
  LDP HOWTO coordinator, so if it isn't there then chances are I haven't
  finished it.

  3.  Linux and the AX.25 and NetRom Packet Radio Protocols.

  The AX.25 protocol offers both connected and connectionless modes of
  operation, and is used either by itself for point-point links, or to
  carry other protocols such as TCP/IP and NetRom.

  It is similar to X.25 level 2 in structure, with some extensions to
  make it more useful in the amateur radio environment.

  The NetRom protocol is an attempt at a full network protocol and uses
  AX.25 at its lowest layer as a datalink protocol. It provides a
  network layer that is an adapted form of AX.25.

  Alan Cox developed some early kernel based AX.25 software support for
  Linux.  Jonathon Naylor <g4klx@g4klx.demon.co.uk> has taken up ongoing
  development of the code, has added NetRom support and is now the
  developer of the AX.25 related kernel code and utilities. DAMA support
  was developed by Joerg, DL1BKE. Finally Baycom support was added by
  Thomas Sailer, <sailer@ife.ee.ethz.ch>.

  The Linux code supports KISS based TNC's (Terminal Node Controllers),
  the Ottawa PI card, the Gracilis PacketTwin card and other Z8530 SCC
  based cards with the generic SCC driver and both the Parallel and
  Serial port Baycom modems.

  The User programs contain a simple PMS (Personal Message System), a
  beacon facility, a line mode connect program, `listen' an example of
  how to capture all AX.25 frames at raw interface level and programs to
  configure the NetRom protocol. Included also are an AX.25 server style
  program to handle and despatch incoming AX.25 connections and a NetRom
  daemon which does most of the hard work for NetRom support.

  4.  The AX.25/NetRom software components.

  The AX.25 software is comprised of three components, the kernel
  source, the network configuration tools and the utility programs.

  The version 1.3.xx Linux kernels include the AX.25, NetRom, Z8530 SCC,
  PI card and PacketTwin drivers by default. I recommend you obtain and
  use the version 1.3.xx kernel source.

  These are three reasons I'm recommending you use the alpha version
  software even though most everyone else will recommend you don't use
  it:

  �  it makes the process of building and configuring the software a
     whole lot simpler. There are no patches to apply it is a simple
     matter of configuring and compiling a kernel with the appropriate
     options enabled.

  �  it is the most recent software and is most likely to provide the
     most satisfactory results.

  �  like all new software, it needs testing and bug reports. The more
     people that take the software and attempt to use it in their own
     configurations the more likely it will be that bugs are uncovered
     and the easier it will be to get the software debugged. Join the
     team, contribute bug reports and help everybody.
  Be warned though, this software is alpha and may have problem that you
  wouldn't otherwise encounter. Please take all the usual precautions
  and be sure to keep a working kernel as backup when testing new
  kernels. It is wise to test a new kernel by booting from it from
  floppy before actually installing it with lilo, though I haven't
  bothered for about 90 kernels revisions so I'm fairly confident you
  can pretty safely run with alpha kernels.

  4.1.  Finding the kernel, tools and utility packages.

  4.1.1.  The kernel source:

  The kernel source can be found in its usual place at:

  ftp.funet.fi

       /pub/Linux/PEOPLE/Linus/v2.0/

  4.1.2.  The network tools:

  The latest alpha release of the standard Linux network tools support
  AX.25 and NetRom and can be found at:

  ftp.inka.de

       /pub/comp/Linux/networking/net-tools/net-tools-1.32-alpha.tar.gz

  or:

  ftp.linux.org.uk

       /pub/linux/Networking/PROGRAMS/NetTools/net-tools-1.32-alpha.tar.gz

  The latest ipfwadm package can be found at:

  ftp.xos.nl

       /pub/linux/ipfwadm/

  4.1.3.  The AX25 utilities:

  The AX.25 utility programs can be found at:

  sunsite.unc.edu

  /pub/Linux/apps/ham/ax25-utils-2.0.0.tar.gz

  or:

  ftp.ucsd.edu

       /hamradio/packet/tcpip/incoming/ax25-utils-2.0.0.tar.gz

  5.  Installing the AX.25/NetRom software.

  To successfully install AX.25 support on your linux system you must
  configure and install an appropriate kernel and then install the AX.25
  utilities.

  5.1.  Compiling the kernel.

  If you are already familiar with the process of compiling the Linux
  Kernel then you can skip this section, just be sure to select the
  appropriate options when compiling the kernel. If you are not, then
  read on.

  The normal place for the kernel source to be unpacked to is the
  /usr/src directory into a subdirectory called linux.  To do this you
  should be logged in as root and execute a series of commands similar
  to the following:

       # mv linux linux.old
       # cd /usr/src
       # gzip -dc linux-2.0.0.tar.gz | tar xvofp -
       # cd linux

  After you have unpacked the kernel source into place you need to run
  the configuration script and choose the options that suit your
  hardware configuration and the options that you wish built into your
  kernel.  You do this by using the command:

       # make config

  You might also try:

       # make menuconfig

  if you prefer a full screen menu based method. I'm going to describe
  the original method, but you use whichever you are most comfortable
  with.

  In either case you will be offered a range of options at which you
  must answer `Y' or `N'. (Note you may also answer `M' if you are using
  modules.  For the sake of simplicity I will assume you are not, please
  make appropriate modifications if you are).

  The options most relevant to an AX.25 configuration are:

  Networking support (CONFIG_NET) [Y/n/?]                             Y
  Loopback device support (CONFIG_BLK_DEV_LOOP) [N/y/m/?]             Y
  Network firewalls (CONFIG_FIREWALL) [N/y/?]
  TCP/IP networking (CONFIG_INET) [Y/n/?]                             Y
  IP: forwarding/gatewaying (CONFIG_IP_FORWARD) [N/y/?]
  IP: firewalling (CONFIG_IP_FIREWALL) [N/y/?] (NEW)
  IP: tunneling (CONFIG_NET_IPIP) [N/y/m/?] (NEW)
  Amateur Radio AX.25 Level 2 (CONFIG_AX25) [N/y/?]                   Y
  AX.25 over Ethernet (CONFIG_BPQETHER) [N/y/?] (NEW)
  Amateur Radio NET/ROM (CONFIG_NETROM) [N/y/?] (NEW)
  Kernel/User network link driver(ALPHA) (CONFIG_NETLINK) [N/y/?]
  Network device support (CONFIG_NETDEVICES) [Y/n/?]                  Y
  SLIP (serial line) support (CONFIG_SLIP) [N/y/m/?]                  Y
  Radio network interfaces (CONFIG_NET_RADIO) [N/y/?]
  BAYCOM ser12 and par96 kiss emulation driver for AX.25 (CONFIG_BAYCOM) [N/y/m/?]
  Z8530 SCC kiss emulation driver for AX.25 (CONFIG_SCC) [N/y/m/?]
  Other ISA cards (CONFIG_NET_ISA) [N/y/?]
  Ottawa PI and PI/2 support (CONFIG_PI) [N/y/?] (NEW)
  Gracilis PackeTwin support (CONFIG_PT) [N/y/?] (NEW)
  Standard/generic serial support (CONFIG_SERIAL) [Y/n/?]

  The options I have flagged with a `Y' are those that you must must
  answer `Y' to. The rest are dependent on what hardware you have and
  what options you want to include. Some of these options are described
  in more detail later on, so if you don't know what you want yet, then
  read ahead and come back to this step later.

  After you have completed the kernel configuration you should be able
  to cleanly compile your new kernel:

       # make dep
       # make clean
       # make zImage

  Make sure you move your arch/i386/boot/zImage file wherever you want
  it and then run lilo to ensure that you actually boot from it.

  5.2.  The network configuration tools.

  After you have compiled the kernel you should compile the new network
  configuration tools. These tools allow you to modify the configuration
  of network devices and to add routes to the routing table.

  The new alpha release of the standard net-tools package includes
  support for AX.25 and NetRom support. I've tested this and it seems to
  work well for me.
  5.2.1.  Building the standard net-tools release.

  Don't forget to read the Release file and follow any instructions
  there. The steps I used to compile the tools were:

       # cd /usr/src
       # tar xvfz net-tools-1.32-alpha.tar.gz
       # cd net-tools-1.32-alpha
       # make config

  At this stage you will be presented with a series of configuration
  questions, similar to the kernel configuration questions. Be sure to
  include support for all of the protocols and network devices types
  that you intend to use. If you do not know how to answer a particular
  question then answer `Y'.

  The tools compiled cleanly against a 2.0.0 kernel without error.

  When the compilation is complete, you should need only use the:

       # make install

  command to install the programs in their proper place.

  If you wish to use the IP firewall facilities then you will need the
  latest firewall administration tool ipfwadm. This tool replaces the
  older ipfw tool which will not work with new kernels.

  I compiled the ipfwadm utility with the following commands:

       # cd /usr/src
       # tar xvfz ipfwadm-2.0beta2.tar.gz
       # cd ipfwadm-2.0beta2
       # make install
       # cp ipfwadm.8 /usr/man/man8
       # cp ipfw.4 /usr/man/man4

  5.3.  The AX.25 user programs.

  After you have successfully compiled and booted your new kernel, you
  need to compile the user programs. To compile and install the user
  programs you should use a series of commands similar to the following:

  # cd /usr/local
  # gzip -dc ax25-utils-2.0.0.tar.gz | tar xvvof -
  # cd ax25-utils-2.0
  # make install

  The files will be installed under the /usr/local directory by default
  in subdirectories: bin, sbin, etc and man.

  If you get messages something like:

  gcc -Wall -Wstrict-prototypes -O2 -I../lib -c call.c
  call.c: In function `statline':
  call.c:268: warning: implicit declaration of function `attron'
  call.c:268: `A_REVERSE' undeclared (first use this function)
  call.c:268: (Each undeclared identifier is reported only once
  call.c:268: for each function it appears in.)

  then you should read the README.ncurses file in the top level
  directory. You can do as Jonathon suggests, or you can try replacing:

  #include <curses.h>

  with:

  #include <ncurses/curses.h>

  in the:

  call/call.c
  call/menu.c

  files.

  6.  Configuring a RAW AX.25 connected mode interface.

  The first stage to configuration of an AX.25 interface is to configure
  it to work as a `vanilla' AX.25 interface with no TCP/IP. The
  following configuration will get you to the point of being able to
  make AX.25 calls from your Linux machine to other AX.25 nodes.

  The AX.25 software has been designed to work with a TNC in kiss mode
  or with other cards such as the Ottawa PI2 card, PacketTwin and other
  SCC cards via special drivers that emulate a kiss tnc.

  For real KISS TNC's there are two steps to complete in order to create
  an AX.25 port ready to use to make outgoing calls. For other types of
  hardware you need only complete the first step.

  6.1.  Creating the /usr/local/etc/axports file.

  The AX.25 ports have a configuration file that is read by many
  programs that want to find information about an AX.25 port. This file
  is called the:

  /usr/local/etc/axports

  file. The format of the file is as follows:

       portname  callsign  baudrate  paclen  window  description

  where:

     portname
        is a text name that you will refer to the port by.

     callsign
        is the AX.25 callsign you want to assign to the port.

     baudrate
        is the speed at which you wish the port to communicate with your
        TNC.

     paclen
        is the maximum packet length you want to configure the port to
        use for AX.25 connected mode connections.

     window
        is the AX.25 window (K) parameter. This is the same as the
        MAXFRAME setting of many tnc's.

     description
        is a textual description of the port.

  In my case, mine looks like:

       radio    VK2KTJ-0        4800    256     2       144.800 MHz

  6.2.  Creating the AX.25 device

  If you are using an SCC card like the PI2 or PacketTwin then you do
  not need to create the network device, as the kernel driver will
  automatically do this for you. If you are using a KISS TNC then you
  will need to create the AX.25 interface as it will not already exist.
  Creating an AX.25 port is very similar to creating a slip device.

  You will need to have the TNC preconfigured and connected to your
  serial port.  You can use a communications program like minicom or
  seyon to configure the TNC into kiss mode if you wish.

  You use the axattach program in much the same way as you would use the
  slattach program (refer to the NET-2-HOWTO for more information on
  slattach and the other network software for Linux). For example:

  # /usr/local/sbin/axattach /dev/ttyS0 radio

  would configure your /dev/ttyS1 serial device to be a kiss interface
  configured as per the details for the line beginning with the portname
  "radio" in the /usr/local/etc/axports file.

  All this step has done is to actually activate the device in the
  kernel, you need to run other programs before you an actually make use
  of the port.

  6.2.1.  Setting the callsign for SCC cards.

  If you are using a PI or PacketTwin card then you should use the
  axparms -setcall command to change the callsign of the appropriate
  port to that which you intend to use. Refer to the PI/PacketTwin
  section for the names of the network devices to use.

  6.2.2.  Testing the interface.

  You now should be able to make outgoing AX.25 connections. To test
  AX.25 connected mode you could use the call program as demonstrated:

       /usr/local/bin/call radio VK2DAY via VK2SUT

  Note: you must tell call which AX.25 port you wish to make the call
  on, as the same AX.25 node might be reachable on any of the ports you
  have configured.

  The call program is a linemode terminal program for making AX.25
  calls. It recognises lines that start with `~' as command lines.  The
  `~.' command will close the connection.

  Please refer to the man pages in /usr/local/man and the README file in
  ax25-utils-2.0.0 distribution for more information.

  7.  Configuring an AX.25 interface for tcp/ip.

  It is very simple to configure an AX.25 port to carry tcp/ip. Jonathon
  has modified the axattach command so that you can include the IP
  address that you want the interface to be configured with on the
  command line. For example, to modify the example presented earlier, I
  could use the command:

       # /usr/local/sbin/axattach -i 44.136.8.5 -m 512 /dev/ttyS0 radio
       # /sbin/route add -net 44.136.8.0 sl0
       # /sbin/route add default sl0

  to create the AX.25 interface with an IP address of 44.136.8.6 and an
  MTU of 512 bytes. You should still use the ifconfig to configure the
  other parameters if necessary.

  You do not need to do it this way, you can of course just use the
  ifconfig program to configure the ip address and netmask details for
  the port and add a route via the port, just as you would for any other
  tcp/ip interface.

       # /sbin/ifconfig sl0 44.136.8.5
       # /sbin/ifconfig sl0 netmask 255.255.255.0
       # /sbin/ifconfig sl0 broadcast 44.136.8.255
       # /sbin/ifconfig sl0 arp mtu 256 up
       # /sbin/route add -net 44.136.8.0 sl0
       # /sbin/route add default sl0

  The commands listed above are typical of the sort of configuration
  many of you would be familiar with if you have used NOS or any of its
  derivatives or any other tcp/ip software. Note that the default route
  might not be required in your configuration if you have some other
  network device configured.

  To test it out, try a ping or a telnet to a local host.

       # ping -i 5 44.136.8.58

  Note the use of the `-i 5' arguments to ping to tell it to send pings
  every 5 seconds instead of its default of 1 second.

  8.  Configuring an AX.25 interface for NetRom.

  To configure NetRom on an AX.25 interface you must configure two
  files.

  8.1.  Configuring /usr/local/etc/nrports

  The first is the /usr/local/etc/nrports file. This file describes the
  NetRom port in much the same way as the /usr/local/etc/axports file
  describes the AX.25 ports.

  This file is formatted as follows:

       name callsign  alias  paclen   description

  Where:

     name
        is the text name that you wish to refer to the port by.

     callsign
        is the callsign that the NetRom traffic from this port will use.
     alias
        is the NetRom alias this port will have assigned to it.

     paclen
        is the maximum size of NetRom frames transmitted by this port.

     description
        is a free text description of the port.

  An example would look something like the following:

       netrom  VK2KTJ-1        LINUX   235     Linux Switch Port

  Note that the ports are referred to by name by programs such as call.

  8.2.  Configuring /usr/local/etc/nrbroadcast

  The second file is the /usr/local/etc/nrbroadcast file.

  This file is formatted as follows:

       axport min_obs def_qual worst_qual verbose

  Where:

     axport
        is the port name obtained from the /usr/local/etc/axports file.
        If you do not have an entry in /usr/local/etc/nrbroadcasts for a
        port then this means that no NetRom routing will occur and any
        received NetRom broadcasts will be ignored for that port.

     min_obs
        is the minimum obselesence value for the port.

     def_qual
        is the default quality for the port.

     worst_qual
        is the worst quality value for the port, any routes under this
        quality will be ignored.

     verbose
        is a flag determining whether full NetRom routing broadcasts
        will occur from this port or only a routing broadcast
        advertising the node itself.

  An example would look something like the following:

       radio    1       200      10         1

  8.3.  Creating the NetRom device

  When you have the two configuration files completed you must create
  the NetRom device in much the same way as you did for the AX.25
  devices.  This time you use the nrattach command:

       # nrattach netrom

  This command would start the NetRom device (nr0) named netrom
  configured with the details specified in the /usr/local/etc/nrports
  file.

  8.4.  Starting the NetRom daemon

  The NetRom daemon manages the NetRom routing tables and generates the
  NetRom routing broadcasts. You start NetRom with the command:

       # /usr/local/sbin/netromd

  You should soon see the /proc/net/nr_neigh file filling up with
  information about your NetRom neighbours.

  Remember to put the /usr/local/sbin/netromd command in your rc files
  so that it is started automatically each time you reboot.

  9.  Configuring IP on a NetRom interface.

  Configuring a NetRom interface for tcp/ip is almost identical to
  configuring an AX.25 interface for tcp/ip.

  Again you can either specify the ip address and mtu on the nrattach
  command line, or use the ifconfig and route commands, but you need to
  manually add arp entries for hosts you wish to route to because there
  is no mechanism available for your machine to learn what NetRom
  address it should use to reach a particular IP host.

  So, to create an nr0 device with an IP address of 44.136.8.5 and an
  mtu of 512 and configured with the details from the
  /usr/local/etc/nrports file for a NetRom port named netrom you would
  use:

       # /usr/local/sbin/nrattach -i 44.136.8.5 -m 512 netrom
       # route add 44.136.8.5 nr0

  or you could use something like the following commands manually:

  # ifconfig nr0 44.136.8.5 hw netrom VK2KTJ-1
  # route add 44.136.8.5 nr0

  Then for each IP host you wish to reach via NetRom you need to set
  route and arp entries. To reach a destination host with an IP address
  of 44.136.80.4 at NetRom address BBS:VK3BBS via a NetRom neighbour
  with callsign VK2SUT-0 you would use commands as follows:

       # route add 44.136.80.4 nr0
       # arp -t netrom -s 44.136.80.4 vk2sut-0
       # nrparms -nodes vk3bbs + BBS 120 6 sl0 vk2sut-0

  The `120' and `6' arguments to the nrparms command are the NetRom
  quality and obsolescence count values for the route.

  10.  Configuring an Ethernet device for AX.25 ala BPQ

  Linux support BPQ Ethernet compatibility. This enables you to run the
  AX.25 protocol over your Ethernet LAN and to interwork your linux
  machine with other BPQ machines on the LAN.

  Configuration is quite straightforward. You firstly must have
  configured a standard Ethernet device. This means you will have
  compiled your kernel to support your Ethernet card, and executed
  configuration commands similar to the following:

       # ifconfig eth0 44.136.8.5 netmask 255.255.255.248 up
       # ifconfig eth0 broadcast 44.136.8.103
       # route add -net 44.136.8.96 netmask 255.255.255.248 eth0

  To configure the BPQ support you need to associate an AX.25 callsign
  with your Ethernet hardware address. You should use the following:

       # axparms -dev eth0 vk2ktj-9

  This says that AX.25 callsign vk2ktj-9 is associated with the eth0
  device.

  BPQ Ethernet normally uses a multicast address. The Linux
  implementation does not, and instead it uses the normal Ethernet
  broadcast address. The NET.CFG file for the BPQ ODI driver should
  therefore look similar to this:

  LINK SUPPORT

          MAX STACKS 1
          MAX BOARDS 1

  LINK DRIVER E2000                    ; or other MLID to suit your card

          INT 10                       ;
          PORT 300                     ; to suit your card

          FRAME ETHERNET_II

          PROTOCOL BPQ 8FF ETHERNET_II ; required for BPQ - can change PID

  BPQPARMS                             ; optional - only needed if you want
                                       ; to override the default target addr

          ETH_ADDR  FF:FF:FF:FF:FF:FF  ; Target address

  11.  Ottawa PI/PI2 card driver and Gracilis PacketTwin driver.

  The Ottawa PI and the Gracilis PacketTwin are Z8530 SCC based card for
  IBM PC type machines that are in common usage by Amateur Radio
  operators worldwide.  The PI card supports a high speed half duplex
  (single DMA channel) port, and a low speed (<9k6bps interrupt driven)
  half duplex port. The PI2 is a new version of the card that supports
  an on board radio modem and improved hardware design. The PacketTwin
  card supports two high speed port and is capable of accepting on board
  modems.

  The PI card driver was written by David Perry, <dp@hydra.carleton.edu>
  The PacketTwin card driver was written by Craig Small VK2XLZ,
  <csmall@triode.apana.org.au>.  Both drivers are a standard feature of
  the 1.3.xx kernel.

  Please refer to the AX.25 section above for details on how to
  configure the kernel to include the PI card or the PacketTwin card
  drivers.

  Once you have the appropriate driver configured into your kernel then
  you should reboot and when you do, you should see mention of the PI or
  PacketTwin card driver in the messages that appear on the screen while
  the kernel is booting. The drivers test each of the I/O port addresses
  that the card might be configured for and reports any that it finds.
  You should then look at the /proc/net/dev file and you should see
  reference to devices called pi0a and pi0b or pt0a and pt0b for the PI
  and PacketTwin cards respectively.

  If the devices don't appear then recheck that you have configured and
  compiled your kernel correctly and that you are in fact actually
  running your new kernel. If you still don't then this suggests that
  your PI or PacketTwin card was not detected by the kernel while it
  booted and may indicate that you have some sort of hardware
  conflicting with your PI/PT card that prevented it being detected.

  If all of the above went as planned then you will need to configure
  your PI/PT card with an AX.25 address and for IP. The configuration of
  the PI/PT cards is virtually identical to that of any other IP
  interface. Something like the following should work ok for you:

       # /usr/local/sbin/axparms -setcall pi0a VK2KTJ-2
       # /sbin/ifconfig pi0a 44.136.8.5
       # /sbin/ifconfig pi0a netmask 255.255.255.0
       # /sbin/ifconfig pi0a broadcast 44.136.8.255
       # /sbin/ifconfig pi0a arp mtu 256 up
       # /sbin/route add -net 44.136.8.0 pi0a
       # /sbin/route add default pi0a

  Note that pi0a refers to the `a' port on the first PI card found, and
  that pi0b would therefore refer to the `b' port on the first PI card
  found. pt0a would therefore be the first port on the first PacketTwin
  card detected.

  Note also the use of the axparms -setcall command to set the AX.25
  callsign of the port.

  As usual, when this has been done you can test the interface with the
  ping or telnet command to ensure it is working.

  12.  Z8530 SCC Kiss Emulation

  Joerg Reuter, DL1BKE has developed generic support for Z8530 SCC based
  cards.  His driver is configurable to support a range of different
  types of cards and present an interface that looks like a KISS TNC so
  you can treat it as though it were a KISS TNC.

  12.1.  Obtaining and building the configuration tool package.

  The kernel driver is included in the standard kernel distribution, but
  there are a suite of configuration tools that you will need to obtain
  as well.

  To compile the kernel support you must be sure to answer `Y' to:
  `Z8530 SCC kiss emulation driver for AX.25' when asked during a kernel
  `make config'.

  You can obtain the configuration tools package from:

  ftp.ucsd.edu

       /hamradio/packet/tcpip/incoming/z8530drv-2.0.dl1bke.real.tar.gz

  The following command were what I used to compile and install the
  package for kernel version 1.3.93:

       # cd /usr/src
       # gzip -dc z8530drv-2.0.dl1bke.real.tar.gz | tar xvpofz -
       # cd z8530drv
       # rm gencfg sccinit sccstat
       # make dep
       # make utils
       # make install

  Note: I've not followed the instructions included because the version
  of driver in the 2.0.0 kernel is actually newer than that included in
  the package and the normal installation process would have overwritten
  the new kernel source with the older version.

  After the above is complete you should have three new programs
  installed in your /sbin directory: gencfg, sccinit and sccstat. It is
  these programs that you will use to configure the driver for your
  card.

  You will also have a group of new special device files created in your
  /dev called scc0 .. scc7. These will be used later and will be the
  `KISS' devices you will end up using.

  12.2.  Configuring the driver for your card.

  The z8530 SCC driver has been designed to be as flexible as possible
  so as to support as many different types of cards as possible. With
  this flexibility has come some cost in configuration.

  There is more comprehensive documentation in the package and you
  should read this if you have any problems. You should particularly
  look at doc/scc_eng.doc or doc/scc_ger.doc for more detailed
  information. I've paraphrased the important details, but as a result
  there is a lot of lower level detail that I have not included.

  The main configuration file is read by the sccinit program and is
  called /etc/z8530drv.rc. This file is broken into two main stages:
  Configuration of the hardware parameters and channel configuration.
  After you have configured this file you need only add:

       # sccinit

  into the rc file that configures your network and the driver will be
  initialised according to the contents of the configuration file. You
  must do this before you attempt to use the driver.

  12.2.1.  Configuration of the hardware parameters.

  The first section is broken into stanzas, each stanza representing an
  8530 chip. Each stanza is a list of keywords with arguments. You may
  specify up to four SCC chips in this file by default. The #define
  MAXSCC 4 in scc.c can be increased if you require support for more.

  The allowable keywords and arguments are:

     chip
        the chip keyword is used to separate stanzas. It will take
        anything as an argument. The arguments are not used.

     data_a
        this keyword is used to specify the address of the data port for
        the z8530 channel `A'. The argument is a hexadecimal number e.g.
        0x300

     ctrl_a
        this keyword is used to specify the address of the control port
        for the z8530 channel `A'. The arguments is a hexadecimal number
        e.g. 0x304

     data_b
        this keyword is used to specify the address of the data port for
        the z8530 channel `B'. The argument is a hexadecimal number e.g.
        0x301

     ctrl_b
        this keyword is used to specify the address of the control port
        for the z8530 channel `B'. The arguments is a hexadecimal number
        e.g. 0x305

     irq
        this keyword is used to specify the IRQ used by the 8530 SCC
        described in this stanza. The argument is an integer e.g. 5

     pclock
        this keyword is used to specify the frequency of the clock at
        the PCLK pin of the 8530. The argument is an integer frequency
        in Hz which defaults to 4915200 if the keyword is not supplied.

     board
        the type of board supporting this 8530 SCC. The argument is a
        character string. The allowed values are:

        PA0HZP
           the PA0HZP SCC Card

        EAGLE
           the Eagle card

        PC100
           the DRSI PC100 SCC card

        PRIMUS
           the PRIMUS-PC (DG9BL) card

        BAYCOM
           BayCom (U)SCC card

     escc
        this keyword is optional and is used to enable support for the
        Extended SCC chips (ESCC) such as the 8580, 85180, or the 85280.
        The argument is a character string with allowed values of `yes'
        or `no'. The default is `no'.

     vector
        this keyword is optional and specifies the address of the vector
        latch (also known as "intack port") for PA0HZP cards. There can
        be only one vector latch for all chips. The default is 0.

     special
        this keyword is optional and specifies the address of the
        special function register on several cards. The default is 0.

     option
        this keyword is optional and defaults to 0.

  Some example configurations for the more popular cards are as follows:

     BayCom USCC

     chip    1
     data_a  0x300
     ctrl_a  0x304
     data_b  0x301
     ctrl_b  0x305
     irq     5
     board   BAYCOM
     #
     # SCC chip 2
     #
     chip    2
     data_a  0x302
     ctrl_a  0x306
     data_b  0x303
     ctrl_b  0x307
     board   BAYCOM

     PA0HZP SCC card

          chip 1
          data_a 0x153
          data_b 0x151
          ctrl_a 0x152
          ctrl_b 0x150
          irq 9
          pclock 4915200
          board PA0HZP
          vector 0x168
          escc no
          #
          #
          #
          chip 2
          data_a 0x157
          data_b 0x155
          ctrl_a 0x156
          ctrl_b 0x154
          irq 9
          pclock 4915200
          board PA0HZP
          vector 0x168
          escc no

     DRSI SCC card

          chip 1
          data_a 0x303
          data_b 0x301
          ctrl_a 0x302
          ctrl_b 0x300
          irq 7
          pclock 4915200
          board DRSI
          escc no

  If you already have a working configuration for your card under NOS,
  then you can use the gencfg command to convert the PE1CHL NOS driver
  commands into a form suitable for use in the z8530 driver
  configuration file.

  To use gencfg you simply invoke it with the same parameters as you
  used for the PE1CHL driver in NET/NOS. For example:

       # gencfg 2 0x150 4 2 0 1 0x168 9 4915200

  will generate a skeleton configuration for the OptoSCC card.

  12.2.2.  Channel Configuration

  The Channel Configuration section is where you specify all of the
  other parameters associated with the port you are configuring. Again
  this section is broken into stanzas. One stanza represents one logical
  port, and therefore there would be two of these for each one of the
  hardware parameters stanzas as each 8530 SCC supports two ports.

  These keywords and arguments are also written to the /etc/z8530drv.rc
  file and must appear after the hardware parameters section.

  Sequence is very important in this section, but if you stick with the
  suggested sequence it should work ok. The keywords and arguments are:

     device
        this keyword must be the first line of a port definition and
        specifies the name of the special device file that the rest of
        the configuration applies to. e.g. /dev/scc0

     speed
        this keyword specifies the speed in bits per second of the
        interface. The argument is an integer: e.g. 1200

     clock
        this keyword specifies where the clock for the data will be
        sourced. Allowable values are:

        dpll
           normal halfduplex operation

        external
           MODEM supplies its own Rx/Tx clock

        divider
           use fullduplex divider if installed.

     mode
        this keyword specifies the data coding to be used. Allowable
        arguments are: nrzi or nrz

     rxbuffers
        this keyword specifies the number of receive buffers to allocate
        memory for. The argument is an integer, e.g. 8.

     txbuffers
        this keyword specifies the number of transmit buffers to
        allocate memory for. The argument is an integer, e.g. 8.

     bufsize
        this keyword specifies the size of the receive and transmit
        buffers. The arguments is in bytes and represents the total
        length of the frame, so it must also take into account the AX.25
        headers and not just the length of the data field. This keyword
        is optional and default to 384

     txdelay
        the KISS transmit delay value, the argument is an integer in mS.

     persist
        the KISS persist value, the argument is an integer.

     slot
        the KISS slot time value, the argument is an integer in mS.

     tail
        the KISS transmit tail value, the argument is an integer in mS.

     fulldup
        the KISS full duplex flag, the argument is an integer.  1==Full
        Duplex, 0==Half Duplex.

     wait
        the KISS wait value, the argument is an integer in mS.

     min
        the KISS min value, the argument is an integer in S.

     maxkey
        the KISS maximum keyup time, the argument is an integer in S.

     idle
        the KISS idle timer value, the argument is an integer in S.

     maxdef
        the KISS maxdef value, the argument is an integer.

     group
        the KISS group value, the argument is an integer.

     txoff
        the KISS txoff value, the argument is an integer in mS.

     softdcd
        the KISS softdcd value, the argument is an integer.

     slip
        the KISS slip flag, the argument is an integer.

  12.3.  Using the driver.

  To use the driver you simply treat the /dev/scc* devices just as you
  would a serial tty device with a KISS TNC connected to it. For
  example, to configure Linux Kernel networking to use your SCC card you
  could use something like:

       # axattach -s 4800 /dev/scc0 VK2KTJ

  You can also use NOS to attach to it in precisely the same way. From
  JNOS for example you would use something like:
       attach asy scc0 0 ax25 scc0 256 256 4800

  12.4.  The sccstat and sccparam tools.

  To assist in the diagnosis of problems you can use the sccstat program
  to display the current configuration of an SCC device. To use it try:

       # sccstat /dev/scc0

  you will displayed a very large amount of information relating to the
  configuration and health of the /dev/scc0 SCC port.

  The sccparam command allows you to change or modify a configuration
  after you have booted. Its syntax is very similar to the NOS param
  command, so to set the txtail setting of a device to 100mS you would
  use:

       # sccparam /dev/scc0 txtail 0x8

  13.  Configuring an interface for a Baycom modem.

  Thomas Sailer, <sailer@ife.ee.ethz.ch>, despite the popularly held
  belief that it would not work very well, has developed Linux support
  for Baycom modems. His driver supports the Ser12 serial port, Par96
  and the enhanced Par97 parallel port modems.

  When the driver is running it follows the standard of looking like a
  KISS interface, so you treat it in much the same way as you would the
  PI card, PacketTwin or SCC driver ports.

  13.1.  Compiling the kernel

  The driver is only available as a module, so you must have compiled
  module support into your kernel, and also selected the appopriate
  options to support the Baycom driver during the make config stage when
  compiling your kernel.

  The relevant options that you must answer `Y' for are:

       Radio network interfaces (CONFIG_NET_RADIO) [N/y/?]
       BAYCOM ser12 and par96 kiss emulation driver for AX.25 (CONFIG_BAYCOM) [N/y/m/?]

  13.2.  Creating the /dev device files.

  The Baycom driver uses special device files in the /dev directory.
  You need to create these manually. The following commands should work
  ok for you:

       # mknod /dev/bc0 c 60 0
       # mknod /dev/bc1 c 60 1
       # mknod /dev/bc2 c 60 2
       # mknod /dev/bc3 c 60 3

  You will use these later.

  13.3.  Loading the module.

  When the kernel compilation is complete and you have installed the
  module baycom.o wherever you normally keep your modules
  (conventionally they are stored in /lib/modules/2.0.0/), you must
  start the module.  The module takes configuration paramters from the
  insmod command line, so you must start it manually from an rc file or
  if you use the kerneld program you must configure it with the relevant
  paramters so that it supplies them when it loads the module.

  If you use kerneld you will need to add the following line to your
  /etc/conf.modules file:

       alias char-major-60 baycom

  There are four main items to specify when loading the module, they
  are:

     modem
        the baycom modem type you are configuring it for.

        1. Ser12 type modem.

        2. Par96 or Par97 type modem.

     iobase
        the i/o address of the serial or parallel port you will use.

        0x3f8
           COM1:

        0x2f8
           COM2:

        0x378
           LPT1:

        0x278
           LPT2:

     irq
        the Interrupt Request (IRQ) line your port will use.

        4  COM1:

        3  COM2:

        7  LPT1:

        5  LPT2:

     options
        some baycom specific options.

        0  use hardware generated DCD signal.

        1  use software DCD signal.

  13.4.  A small trap to be aware of.

  Because the Baycom driver uses the serial and parallel ports of your
  machines, and because it is a low level driver for these, it competes
  with the existing serial and parallel drivers in the kernel. There are
  some ways of working around this problem. The first way is to make
  sure that you load the Baycom module first so that it takes the
  hardware it needs before the serial or parallel device driver modules
  load and search for their own. With the serial driver you have the
  luxury of being able to disable it for a single port using the
  setserial command, this will be demonstrated in the examples. If you
  are using the parallel port modems then beware of the lp.o Line
  Printer and plip.o Parallel Line IP modules.

  13.5.  Some example configurations.

  These examples are for the two most common configurations.

  Disable the serial driver for COM1: then configure the Baycom driver
  for a Ser12 serial port modem on COM1: with the software DCD option
  enabled:

       # setserial /dev/ttyS0 uart none
       # insmod baycom modem=1 iobase=0x3f8 irq=4 options=1

  Par96 parallel port type modem on LPT1: using hardware DCD detection:

       # insmod baycom modem=2 iobase=0x378 irq=7 options=0

  The first device created is /dev/bc0, the second is /dev/bc1 etc.

  13.6.  Configuring multiple devices.

  Using the insmod program and its command line arguments you can only
  configure one Baycom modem. There is a setbaycom utility which I have
  not yet located that will allow you to configure others. If you happen
  to find it please let me know where it is kept so that I can include
  details for it here.

  13.7.  Actually using the devices.

  This device driver when loaded looks like a serial tty driver with a
  KISS TNC attached. This means that configuration of the AX.25 software
  for this driver is identical to the configuration for a KISS TNC
  presented earlier.  You need to use the axattach program and add the
  port to your /usr/local/etc/axports file. The only difference is that
  you would use the device /dev/bc0 instead of /dev/ttyS0.

  14.  Configuring ax25d to accept incoming AX.25/Netrom connections.

  Linux is a powerful operating system and offers a great deal of
  flexibility in how it is configured. With this flexibility comes a
  cost in configuring it to do what you want. When configuring your
  Linux machine to accept incoming AX.25 or NetRom connections there are
  a number of questions you need to ask yourself. The most important of
  which is: "What do I want users to see when they connect?". As
  detailed in the HAM-HOWTO there are BBS systems that are being
  developed that you might want users to see when they connect,
  alternatively you might want to give users a login prompt so that they
  can make use of a shell account, or you might even have written your
  own program, such as a customised database or a game, that you want
  people to connect to.  Whatever you choose, you must tell the AX.25
  software about this so that it knows what software to run when it
  accepts an incoming AX.25 connection.

  14.1.  Creating the /usr/local/etc/ax25d.conf file.

  This file is the configuration file for the ax25d AX.25 daemon which
  handles incoming AX.25 and NetRom connections.

  The file is a little cryptic looking at first, but you'll soon
  discover it is very simple in practice, with a small trap for you to
  be wary of.

  The format of the ax25d.conf file is as follows:

       # This is a comment and is ignored by the ax25d program.
       [<interface_call>]
       <peer1>  window T1 T2 T3 N2 <mode> <uid> <cmd> <cmd-name> <arguments>
       <peer2>  window T1 T2 T3 N2 <mode> <uid> <cmd> <cmd-name> <arguments>
       defaults window T1 T2 T3 N2 <mode> <uid> <cmd> <cmd-name> <arguments>
       <peer3>  window T1 T2 T3 N2 <mode> <uid> <cmd> <cmd-name> <arguments>
       default  window T1 T2 T3 N2 <mode> <uid> <cmd> <cmd-name> <arguments>

  Where:

     #  at the start of a line marks a comment and is completely ignored
        by the ax25d program.

     <interface_call>
        is the AX.25 callsign of the AX.25 or NetRom interface that this
        particular paragraph is for.

     <peer>
        is the callsign of the peer node that this particular
        configuration applies to. If you don't specify an SSID here then
        any SSID will match.

     window
        is the AX.25 Window parameter (K) or MAXFRAME parameter for this
        configuration.

     T1 is the Frame retransmission (T1) timer in half second units.

     T2 is the amount of time the AX.25 software will wait for another
        incoming frame before preparing a response in 1 second units.

     T3 is the amount of time of inactivity before the AX.25 software
        will disconnect the session in 1 second units.

     N2 is the number of consecutive retransmissions that will occur
        before the connection is closed.

     <mode>
        provides a mechanism for determining certain types of general
        permissions. The modes are enabled or disabled by setting or
        resetting bits in an 8 bit map. You set that map by setting
        <mode> to the sum of the following values:

        1  Setup utmp, and run on a ptty (planned).

        2  UNUSED.

        4  UNUSED.

        8  UNUSED.

        16 UNUSED.

        32 UNUSED.

        64 Disallow digipeated uplinks, only allow direct connections.

        128
           Lockout, Barred, immediate disconnect.

     <uid>
        is the userid that the program to be run to support the
        connection should be run as.

     <cmd>
        is the full pathname of the command to be run, with no arguments
        specified.

     <cmd-name>
        is the text that should appear in a ps as the command name
        running (normally the same as <cmd> except without the directory
        path information.

     <arguments>
        are the command line argument to be passed to the <:cmd> when it
        is run. You pass useful information into these arguments by use
        of the following tokens:

        %U AX.25 callsign of the connected party without the SSID, in
           uppercase.

        %u AX.25 callsign of the connected party without the SSID, in
           lowercase.

        %S AX.25 callsign of the connected party with the SSID, in
           uppercase.

        %s AX.25 callsign of the connected party with the SSID, in
           lowercase.

  You need one section in the above format for each AX.25 or NetRom
  interface you want to accept incoming AX.25 or NetRom connections on.

  There are two special lines in the paragraph, one starts with the
  string `defaults' and other starts with the string `default' (yes
  there is a difference). These lines serve special functions.

  The `default' lines purpose should be obvious, this line acts as a
  catch-all, so that any incoming connection on the <interface_call>
  interface that doesn't have a specific rule will match the `default'
  rule. If you don't have a `default' rule, then any connections not
  matching any specific rule will be disconnected immediately without
  notice.

  The `defaults' line is a little more subtle, and here is the trap I
  mentioned earlier. In any of the fields for any definition for a peer
  you can use the `*' character to say `use the default value'. The
  `default' line is what sets those default values. The kernel software
  itself has some defaults which will be used if you don't specify any.
  The trap is that the these defaults apply only to those rules below
  the `default' line not to those above. You may have more than one
  `default' rule per interface definition, and in this way you may
  create groups of default configurations.

  14.2.  A simple example ax25d.conf file.

  Ok, an illustrative example:

       # ax25d.conf for VK2KTJ - 21/11/95
       # This configuration uses the AX.25 port defined earlier.
       [VK2KTJ-1]
       NOCALL     *     *  *  *  *   0    guest /usr/games/fortune
       defaults   1    10  *  *  *   0    root  /usr/local/sbin/axspawn axspawn %u +
       VK2XLZ-1   *     *  *  *  *   *      *     *         *
       VK2DAY-1   *     *  *  *  *   *      *     *         *
       default    1    10  5 100 5   0    root  /usr/local/bin/pms pms -a -o vk2ktj
       #

  This example says that anybody connecting to the interface on my
  machine with the callsign VK2KTJ-1 will have the following rules
  applied:

  Anyone whose callsign is set to `NOCALL' should use the kernel default
  parameters and have the fortune program run as guest for them.

  The defaults line changes two parameters from the kernel defaults
  (Window and T1) and will run the /usr/local/sbin/axspawn program for
  them. Any copies of /usr/local/sbin/axspawn run this way will appear
  as axspawn in a ps listing for convenience. The next two lines
  definitions for two stations who will receive those permissions.

  The last line in the paragraph is the `catch all' definition that
  everybody else will get (including VK2XLZ and VK2DAY using any other
  SSID other than -1).  This definition sets all of the parameters
  implicitly and will cause the pms program to be run with a command
  line argument indicating that it is being run for an AX.25 connection
  (assuming VK2KTJ-1 to be an AX.25 interface) and that the owner
  callsign is VK2KTJ. (See the `Configuring the PMS' section below for
  more details).

  If you wanted to define rules for another interface, a NetRom
  interface for example, then you would add another paragraph coded in
  the same way with rules and callsign appropriate to it.

  This example is a contrived one but I think it illustrates clearly the
  important features of the syntax of the configuration file. Jonathon
  includes a much longer and more detailed example in the ax25-utils
  package that you should look at if you need more information.

  14.3.  Starting ax25d

  When you have the two configuration files completed you start ax25d
  with the command:

       # /usr/local/sbin/ax25d

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