Messages in this thread | | | Date | Mon, 06 Feb 2006 09:22:15 -0500 | From | Guillaume Filion <> | Subject | AX.25 ARP debugging |
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Hi all,
I'm playing with openslug and AX.25 and I'm having problems passing IP through AX.25. They are connected by a serial link. The link works at the AX.25 level: it works with call. But I cannot get it to work with IP. Bob W5/VK2YQA on rec.radio.amateur.digital.misc helped me pinpoint this to a arp problem, but now I'm at loss on how to debug it further...
My config: I have a PC running Debian Linux testing (ali) and a NSLU2 running N7IPB's OpenSlug mod (http://wetnet.net/). ===== ali:~# uname -a Linux ali 2.4.27-2-k7 #1 Tue Aug 16 17:30:14 JST 2005 i686 GNU/Linux ali:~# ifconfig ax0 ax0 Link encap:AMPR AX.25 HWaddr VA2JF-1 inet addr:172.25.25.1 Bcast:172.25.255.255 Mask:255.255.0.0 UP BROADCAST RUNNING MTU:1500 Metric:1 RX packets:211 errors:0 dropped:0 overruns:0 frame:0 TX packets:17800 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:10 RX bytes:6282 (6.1 KiB) TX bytes:1740572 (1.6 MiB) ali:~# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 172.25.25.0 0.0.0.0 255.255.255.0 U 0 0 0 ax0 10.10.16.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 172.25.0.0 0.0.0.0 255.255.0.0 U 0 0 0 ax0 0.0.0.0 192.168.0.3 0.0.0.0 UG 0 0 0 eth0 ===== root@slug:~# uname -a Linux slug 2.6.11.2 #1 Mon Dec 5 06:24:32 PST 2005 armv5teb unknown root@slug:~# ifconfig ax0 ax0 Link encap:AMPR AX.25 HWaddr VA2JF-2 inet addr:172.25.25.2 Bcast:172.25.255.255 Mask:255.255.0.0 UP BROADCAST RUNNING MTU:1500 Metric:1 RX packets:52 errors:0 dropped:0 overruns:0 frame:0 TX packets:22 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:10 RX bytes:4238 (4.1 Kb) TX bytes:898 (898.0 b) root@slug:~# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 172.25.0.0 0.0.0.0 255.255.0.0 U 0 0 0 ax0 0.0.0.0 192.168.0.3 0.0.0.0 UG 0 0 0 eth0 =====
The actual problem: ===== root@slug:~# arp -an ? (192.168.0.5) at 00:01:53:80:57:E6 [ether] on eth0 root@slug:~# arp -H ax25 -i ax0 -s 172.25.25.1 VA2JF-1 root@slug:~# arp -an ? (172.25.25.1) at * [ax25] PERM on - ? (192.168.0.5) at 00:01:53:80:57:E6 [ether] on eth0 root@slug:~# cat /proc/net/arp IP address HW type Flags HW address Mask Device 172.25.25.1 0x3 0x6 * ax0 192.168.0.5 0x1 0x2 00:01:53:80:57:E6 * eth0 =====
I can confirm the problem with tcpdump: ===== root@ali:~/tcpdump-ax25/tcpdump-3.9.3# ./tcpdump -envi ax0 tcpdump: listening on ax0, link-type AX25 (AX.25), capture size 96 bytes
[... root@slug:~# ping 172.25.25.1 ...] 17:30:01.703620 VA2JF-2 > -6: Res 3, C/R 0, UI, ?, pf 0, length 101: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto: ICMP (1), length: 84) 172.25.25.2 > 172.25.25.1: ICMP echo request, id 1691, seq 0, length 64 [... Notice the "VA2JF-2 > -6" instead of "VA2JF-2 > VA2JF-1" ...]
[... root@ali:~# ping 172.25.25.2 ...] 17:31:24.033354 VA2JF-1 > VA2JF-2: Res 3, C/R 0, UI, ?, pf 0, length 101: (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto: ICMP (1), length: 84) 172.25.25.1 > 172.25.25.2: ICMP echo request, id 6003, seq 1, length 64 [... I never get an answer from slug, I guess it's because slug's arp table doesn't contain ali's address ...] =====
Any help appreciated, GFK's -- Guillaume Filion, ing. jr Logidac Tech., Beaumont, Québec, Canada - http://logidac.com/ PGP Key and more: http://guillaume.filion.org/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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