Unwanted packets on AX25 interface

Unwanted packets on AX25 interface

[Josh Freeman]

Hello,

I'm running Fedora Core 4 and user-mode Soundmodem 0.10.1 in MKISS
mode to operate APRS, primarily with XASTIR. When I start up
Soundmodem, it creates interface ax0 with an IP address of 10.0.0.1.
It immediately sends a packet

Tx: fm KI4ITI-9 to QST-0 UI  pid=CC
F..(..@................."...............

At other times it transmits packets like

Tx: fm KI4ITI-9 to QST-0 UI  pid=CC
E..Z..@..................F...............1.0.0.10.in-addr.arpa............localhost.local.

Tx: fm KI4ITI-9 to QST-0 UI  pid=CC
E..M..@..................9Z..............localhost.local.....................

Since I'm only operating APRS at this time, these packets are just QRM
that I really need to get rid of. I imagine that they are probably
being generated by mDNS or some other service that advertises on all
the interfaces - but I'm not knowledgeable enough to know how to make
them stop. I have discovered that deleting the route to the 10.0.0.0
network from the kernel routing table with "route del -net
10.0.0.0/24" doesn't do it.

I don't want TCP/IP on ax0 at all. I only want to use XASTIR and
possibly some of the other purely ax25 programs as I learn more about
what I can do with packet radio. Would someone be willing to help me
get this set up correctly?

Thanks
Josh KI4ITI

RE: Unwanted packets on AX25 interface

[AE5PL Lists]

Are you running Samba (standard in FC4)?  If so, restrict it to your LAN
interface or it will send packets out your AX.25 interface.

73,

Pete Loveall AE5PL
mailto:pete@ae5pl.net 

> -----Original Message-----
> From: Josh Freeman
> Posted At: Tuesday, January 24, 2006 3:36 PM
> Subject: Unwanted packets on AX25 interface
> 
> I'm running Fedora Core 4 and user-mode Soundmodem 0.10.1 in 
> MKISS mode to operate APRS, primarily with XASTIR. When I 
> start up Soundmodem, it creates interface ax0 with an IP 
> address of 10.0.0.1.
> It immediately sends a packet

Re: Unwanted packets on AX25 interface

[Ralf Baechle DL5RB]

On Tue, Jan 24, 2006 at 03:32:51PM -0600, Josh Freeman wrote:

> I'm running Fedora Core 4 and user-mode Soundmodem 0.10.1 in MKISS
> mode to operate APRS, primarily with XASTIR. When I start up
> Soundmodem, it creates interface ax0 with an IP address of 10.0.0.1.
> It immediately sends a packet

This is a known problem.  For unknown reasons ages ago the use of an IP
address with every AX.25 address was made mandatory and recently DL9SAU
started undoing that again.

Until then you may try to limit the problem by setting up a packet filter
blocking all ARP/IP traffic over your mkiss interface.

  Ralf

Re: Unwanted packets on AX25 interface

[Josh Freeman]

Hello again,

AE5PL Lists wrote:
> Are you running Samba (standard in FC4)?  If so, restrict it to your LAN
> interface or it will send packets out your AX.25 interface.

Yes, and I believe I now have it restricted to the TCP/IP interfaces
(lo, eth0, wlan0), but it turns out that the unwanted packets are
being generated even when the Samba services (smbd and nmbd) aren't
running at all.

John Ronan wrote:
> did you get this fixed? (I'm slowly catching up on my emails)

Not yet =)

Ralf Baechle DL5RB wrote:
> Until then you may try to limit the problem by setting up a packet filter
> blocking all ARP/IP traffic over your mkiss interface.

OK. I'll go do some doc-searching and try to figure out how to set that up.

Thanks for all your responses.

Josh KI4ITI

Re: Unwanted packets on AX25 interface

[John Ronan]

Hmmm,

I'm using a soundmodem configuration at home, and I've never seen a QST
request unless I try and ping someone on the local network. It first
generates an ARP request before the ping.   

I'm trying to think what (other than samba) could be doing this and to
be honest, I'm at a loss (I'm going for coffee now).  What services do
you have running on the machine? Also what is your default route out of
the machine?

Regards
John



> Not yet =)
> 
> Ralf Baechle DL5RB wrote:
> > Until then you may try to limit the problem by setting up a packet filter
> > blocking all ARP/IP traffic over your mkiss interface.
> 
> OK. I'll go do some doc-searching and try to figure out how to set that up.
> 
> Thanks for all your responses.
> 
> Josh KI4ITI

Re: Unwanted packets on AX25 interface

[J. Lance Cotton]

Josh Freeman wrote:
> Yes, and I believe I now have it restricted to the TCP/IP interfaces
> (lo, eth0, wlan0), but it turns out that the unwanted packets are
> being generated even when the Samba services (smbd and nmbd) aren't
> running at all.

Also turn off the mdns service. It's not related to samba. It's some kind of 
auto-finding name service. Apple calls it "Rendezvous", but it has a generic 
name, too; I just can't remember it.

(I don't even know if FC4 has this... SuSE does.
-- 
J. Lance Cotton, KJ5O
joe@lightningflash.net
http://kj5o.lightningflash.net
Three Step Plan: 1. Take over the world. 2. Get a lot of cookies. 3. Eat the 
cookies.

Re: Unwanted packets on AX25 interface

[Jeremy Utley]

On 1/25/06, J. Lance Cotton <joe@lightningflash.net> wrote:

> Also turn off the mdns service. It's not related to samba. It's some kind of
> auto-finding name service. Apple calls it "Rendezvous", but it has a generic
> name, too; I just can't remember it.
>
> (I don't even know if FC4 has this... SuSE does.

The generic name for Rendezvous is zeroconf.  I don't think Fedora has
anything for this integrated yet, but I could be wrong.

Jeremy, NW7JU

Re: Unwanted packets on AX25 interface

[Josh Freeman]

On 1/25/06, J. Lance Cotton <joe@lightningflash.net> wrote:
>
> Also turn off the mdns service. It's not related to samba. It's some kind of
> auto-finding name service. Apple calls it "Rendezvous", but it has a generic
> name, too; I just can't remember it.
>

Ah-ha! Killing mDNS got rid of the first

Tx: fm KI4ITI-9 to QST-0 UI  pid=CC
F..(..@................."...............

packet, anyway. I'll have to use it a bit to see if the others show up
again - from what I've seen so far I can't predict when they'll come
out. I'd wager, though, that mDNS is the culprit there too.

Thanks for the help!

Josh KI4ITI

Re: Unwanted packets on AX25 interface

[Bent Bagger]

Hi all,

I have to pick up this thread again, because I'm being plagued by this
thing. What I experience is that when I configure my AX25 interface
with kissattach, my modem, which is a DSP-12, gets taken out of KISS
mode. The DSP-12 is taken out of KISS mode by receiving 3 ctrl-C
character within 3 seconds.

Ralf,  DL5RB, wrote on Wed Jan 25 2006 :
> This is a known problem. For unknown reasons ages ago the use of an IP
> address with every AX.25 address was made mandatory and recently DL9SAU
> started undoing that again.
>
> Until then you may try to limit the problem by setting up a packet filter
> blocking all ARP/IP traffic over your mkiss interface.

I have gotten rid of the initial IGMP and MDNS packages by using these
rules in my firewall:

iptables -A OUTPUT -o ax0 -j LOG
iptables -A OUTPUT -p igmp -o ax0 -j DROP
iptables -A OUTPUT -p udp -o ax0 -j DROP
(the LOG rule is only there because I am curious as to what actually
goes out ax0)

Now my modem is not reset until I send the first ax25 frame, e.g. by
using the call program, so something is still going out the ax0
interface. iptables does not log 'real' ax25 frames for some reason.

I actually have two questions in this connection:

1) How do I get iptables to access frams at the protocol layers below
IP? I know how to get at the MAC addess, but how do you get at other
protocol than IP?

2) It would probably be a good idea to be able to actually see what
goes on the serial line from my PC to the DSP-12 modem, but apart from
a fullblown hardware protocol analyzer (which I do not have) what tool
are awailable for that kind of sniffing?