ax25rtd.conf - Man Page

ax25 routing daemon configuration file




The file /etc/ax25/ax25rtd.conf is the configuration file for ax25rtd. The parameters of the options shown here are the default values except the ones marked with (example)

ax25-maxroutes 4096

ip-maxroutes 4096

The maximum size of the three lists / caches. On overflow, ax25rtd will substitute the oldest entry with the new one.

iproute2-table radio

name ("radio") of the kernel routing table. This is an advanced routing feature. If you do not need it, just leave this setting as is.

The current implementation  depends on iproute2 (anyone like to code it directly?).

If not set or empty, routes are set in the normal, default, manner. Please configure /etc/iproute2/rt_protos with

 44      ax25rtd

and /etc/iproute2/rt_tables with

 210     radio

where "radio" is the name of the table, (for the configuration example above).

This option is disabled by default.

ip-encaps-dev ipax0

This option was for a patched kernel of the 2.2.x series. Multible interfaces were aggregated to one interface when sending IP frames. This option is disabled by default.


This marks the beginning of per-port definitions. Note that you have to use port names as defined in axports(5) here, anywhere else you may use the port or the device name.

ax25-learn-routes no

Set this to "yes", ax25rtd will add the routing information for every heard frame (with complete digipeater path) to the  kernel AX.25 routing table. Note that ax25rtd's internal cache will be updated anyway, regardless of this option.

ax25-learn-only-mine no

If you set it to "yes", only frames that are sent to (1) the interface callsign, (2) any of the listeners on this device, or (3) the callsigns specified by ax25-more-mycalls will be used to update the internal cache and (depending on ax25-learn-routes) the kernel routing table.

ax25-add-path db0ach (example)

This is useful on DAMA digipeaters. In this case, the DAMA master has to be used for _every_ AX.25 connection, thus ax25rtd will add this digipeater(s) to every target we learn that has no digipeater path (yet). "db0ach" is just an example here.

ax25-more-mycalls dl1bke dl1bke-8 (example)

You can specify more calls as calls here that belong to this interface... "dl1bke" and "dl1bke-8" are examples.

ip-learn-routes no

If set to "yes", ax25rtd will modify the IP routing table if it receives an IP frame (directed to us). This is dangerous!

It should not screw up your routing table, though. Ax25rtd  recognizes the netmask of the device and will adjust the route  only if it fits the netmask and the old route points to one of the devices ax25rtd knows about (hence an AX.25 device).

The problems begin if you have more than one port and a user is able to hear your outgoing traffic on at least two of them.  Due to technical reasons ax25rtd adjusts the route _after_ the  kernel has sent the reply to the received TCP frame already.   This has technical reasons.

If the remote does the same both are switching between the two ports.

Don't use this feature unless you know what you are doing.

It _should_ be safe do enable this on one-port machines, although I strongly recommend to set a network route instead, i.e.:

       route add -net scc3

Note that ax25rtd's internal cache will be updated anyway, regardless of this option.

irtt <irtt>

If ip-learn-routes is enabled this will assign newly added routes an initial round trip time (IRTT) for TCP. <irtt> is measured in msec, hence

       irtt 10000

sets the irtt to 10 seconds. A value of 0 disables this feature (default).

ip-adjust-mode no

If you set this option to "yes" ax25rtd will change the IP encapsulation mode according to the last received IP frame.

The problem with this option is that the kernel AX.25 sends a received IP frame to the IP layer regardless if it was sent in UI frame encapsulation "mode datagram (dg)" or  in I frame encaps, hence in an AX.25 connection, "mode virtual  connect (vc)". The Linux kernel will respond to this frame before ax25rtd can adjust the mode. If the remote does the same... You get the picture.

Don't use this feature unless you know what you are doing.

arp-add no

This option, if set to "yes", changes the ARP table to the  source callsign of the received frame. It should be harmless, just has the the effect that if it is a new entry, the Linux ARP code will send one ARP request before ax25rtd has adjust the ARP table. If there was already an existing ARP entry for this IP route, one IP datagram will be sent to the old address. Not really a problem, I hope.

See Also

ax25rtd(8), ax25rtctl(8).


Joerg Reuter <>
Llaus Kudielka OE1KIB

Referenced By

ax25rtctl(8), ax25rtd(8).

11 November 2003 Linux Programmer's Manual