This just happened (again) on my internet/isdn-dialup server. Short
description: packets get routed to the wrong (isdn-)interface and I
don't know why. Checking the routes with netstat -rn does not show any
reason for it. Here's the long story:
Linux 2.0.33 vanilla + stack overrun patch + unused port monitor patch
gcc 2.7.2.1
ISDN System is from the CVS tree, isdn is 1.31.2.1 (isdn.h)
It's a P166 with 96MB Ram, 3 SCSI HD's, 2 ISDN cards and lot's of
interfaces, isdn as well as aliases to eth.
First, the two interfaces involved:
isdn2 Link encap:10Mbps Ethernet HWaddr FC:FC:C1:8D:A9:A6
inet addr:193.141.169.166 P-t-P:192.168.36.202 Mask:255.255.255.0
UP POINTOPOINT RUNNING NOARP MTU:1500 Metric:1
RX packets:231958 errors:0 dropped:0 overruns:0
TX packets:283934 errors:18 dropped:0 overruns:0
Interrupt:0 Base address:0x0
isdn0 Link encap:10Mbps Ethernet HWaddr FC:FC:C1:8D:A9:A6
inet addr:193.141.169.166 P-t-P:194.120.56.158 Mask:255.255.255.0
UP POINTOPOINT RUNNING NOARP MTU:1500 Metric:1
RX packets:138599 errors:0 dropped:0 overruns:0
TX packets:145020 errors:0 dropped:0 overruns:0
Interrupt:0 Base address:0x0
Here's a short excerpt from netstat -rn (the long one is at the end)
192.168.36.202 0.0.0.0 255.255.255.255 UH 0 0 0 isdn2
192.168.254.1 0.0.0.0 255.255.255.255 UH 0 0 0 isdn0
194.120.56.156 0.0.0.0 255.255.255.252 U 0 0 273 isdn0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 105 isdn0
192.168.37.0 0.0.0.0 255.255.255.0 U 0 0 3 isdn0
192.168.42.0 0.0.0.0 255.255.255.0 U 0 0 0 isdn0
192.168.36.0 192.168.36.202 255.255.255.0 UG 0 0 115 isdn2
When I try to ping 192.168.36.41, it dials isdn0 instead of isdn2,
here's the traceroute:
1 gaston.m.ISAR.de (194.120.56.158) 25.323 ms 41.005 ms 24.19 ms
2 * *
This behaviour shows up only after a few day's uptime and heavy use of
the interfaces.
If somebody has a clue and wants some more information, please feel free
to ask me directly, I'll do all I can...
netstat -rn:
Kernel routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
194.120.56.173 0.0.0.0 255.255.255.255 UH 0 0 8 isdn5
194.122.121.128 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:3
194.122.121.129 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:4
194.122.121.130 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:23
192.168.36.202 0.0.0.0 255.255.255.255 UH 0 0 0 isdn2
192.168.254.1 0.0.0.0 255.255.255.255 UH 0 0 0 isdn0
192.168.0.1 0.0.0.0 255.255.255.255 UH 0 0 4 isdn33
192.168.1.21 0.0.0.0 255.255.255.255 UH 0 0 6 isdn7
192.168.2.21 0..0.0.0 255.255.255.255 UH 0 0 43 isdn7
192.168.32.250 0.0.0.0 255.255.255.255 UH 0 0 0 ippp1
192.168.36.253 0.0.0.0 255.255.255.255 UH 0 0 0 ippp0
192.168.37.1 0.0.0.0 255.255.255.255 UH 0 0 31 isdn3
192.168.37.2 0.0.0.0 255.255.255.255 UH 0 0 2 isdn4
192.168.40.2 0.0.0.0 255.255.255.255 UH 0 0 65 isdn6
192.168.32.12 0.0.0.0 255.255.255.255 UH 0 0 1 ippp2
194.122.121.1 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:0
194.122.121.2 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:2
194.122.121.3 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:5
194.122.121.4 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:6
194.122.121.5 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:9
194.122.121.6 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:11
194.122..121.7 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:12
194.122.121.8 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:14
194.122.121.9 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:7
194.122.121.10 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:8
194.122.121.11 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:10
194.122.121.12 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:13
194.122.121.13 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:15
194.122.121.14 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:16
194.122.121.15 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:17
194.122.121.16 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:18
194.122.121.17 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:19
194.122.121.18 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:20
194.122.121.19 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:21
194.122.121.20 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:22
194.122.121.21 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:24
194.122.121.22 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:25
194.122.121.23 0.0.0.0 255.255.255.255 UH 0 0 0 eth0:26
194.120.56.156 0.0.0.0 255.255.255.252 U 0 0 273 isdn0
193.141.169.160 0.0.0.0 255.255.255.224 U 0 0 285 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 105 isdn0
192.168.37.0 0.0.0.0 255.255.255.0 U 0 0 3 isdn0
192.168.42.0 0.0.0.0 255.255.255.0 U 0 0 0 isdn0
192.168.10.0 0.0.0.0 255.255.255.0 U 0 0 132 isdn1
192.168.20.0 0.0.0.0 255.255.255.0 U 0 0 9 isdn1
192.168.23.0 0.0.0.0 255.255.255.0 U 0 0 0 isdn1
192.168.25.0 0.0.0.0 255.255.255.0 U 0 0 14 isdn1
192.168.30.0 0.0.0.0 255.255.255.0 U 0 0 24 isdn1
192.168.36.0 192.168.36.202 255.255.255.0 UG 0 0 115 isdn2
192.168.2.0 192.168.2.21 255.255.255.0 UG 0 0 49 isdn7
192.168.2.0 192.168.1.21 255.255.255.0 UG 0 0 5 isdn7
192.168.0.0 0.0.0.0 255.255.0.0 U 0 0 5 lo
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 892 lo
0.0.0.0 193.141.169.190 0.0.0.0 UG 1 0 11464 eth0
Klaus Lichtenwalder
------------------------------------------------------------------------
Klaus Lichtenwalder, Dipl. Inform., PGP Key: email to key@Four11.com
Lichtenwalder@ACM.org http://www.wp.com/Klaus
K.Lichtenwalder@Computer.org fax: +49-89-91072699
Mausoberflaechen sind meistens pelzig -- Ricarda