Re: Where are my packets? Was: Unusual routing setup

From: Casey Carter (Casey@Carter.net)
Date: Fri Mar 22 2002 - 20:59:14 EST


Looks like you've broken the routing -- eth1 is receiving packets that
claim eth1 is their source. It would be nice to see the output of "ip
route list table all", and "ip route list table cache" after running the
test program.

Joerg Pommnitz wrote:

>--- Casey Carter <Casey@Carter.net> wrote:
>
>>I'm guessing that your kernel is performing reverse path filtering --
>>i.e., it "knows" that packets from that source address should be coming
>>over the loopback interface, and not ppp0. I suggest that you "echo 0 >
>>
>>/proc/sys/net/ipv4/conf/ppp0/rp_filter" to disable reverse path, and
>>"echo 1 > /proc/sys/net/ipv4/conf/ppp0/log_martians" so you will get log
>>
>>messages for similar stuff.
>>
>
>Hi Casey,
>close, but no cigar. To get off the (expensive) GPRS net I have reproduced
>the setup on the LAN:
>eth0 Link encap:Ethernet HWaddr 00:E0:4C:71:05:92
> inet addr:10.1.12.87 Bcast:10.1.12.255 Mask:255.255.255.0
>eth1 Link encap:Ethernet HWaddr 00:E0:4C:71:05:91
> inet addr:10.1.12.151 Bcast:10.1.12.255 Mask:255.255.255.0
>
>jpo> cat /proc/sys/net/ipv4/conf/eth0/rp_filter
>0
>jpo> cat /proc/sys/net/ipv4/conf/eth1/rp_filter
>0
>jpo> cat /proc/sys/net/ipv4/conf/eth1/log_martians
>1
>jpo> cat /proc/sys/net/ipv4/conf/eth0/log_martians
>0
>
>Running my program results in:
>Mar 22 11:00:07 scorpio_1 kernel: martian source 10.1.12.151 from
>10.1.12.87, on dev eth1
>Mar 22 11:00:07 scorpio_1 kernel: ll header:
>00:e0:4c:71:05:91:00:d0:03:6a:f7:fd:08:00
>Mar 22 11:00:12 scorpio_1 kernel: NET: 4 messages suppressed.
>Mar 22 11:00:12 scorpio_1 kernel: martian source 10.1.12.151 from
>10.1.12.87, on dev eth1
>Mar 22 11:00:12 scorpio_1 kernel: ll header:
>00:e0:4c:71:05:91:00:d0:03:6a:f7:fd:08:00
>Mar 22 11:00:17 scorpio_1 kernel: NET: 4 messages suppressed.
>Mar 22 11:00:17 scorpio_1 kernel: martian source 10.1.12.151 from
>10.1.12.87, on dev eth1
>Mar 22 11:00:17 scorpio_1 kernel: ll header:
>00:e0:4c:71:05:91:00:d0:03:6a:f7:fd:08:00
>Mar 22 11:00:22 scorpio_1 kernel: NET: 4 messages suppressed.
>Mar 22 11:00:22 scorpio_1 kernel: martian source 10.1.12.151 from
>10.1.12.87, on dev eth1
>Mar 22 11:00:22 scorpio_1 kernel: ll header:
>00:e0:4c:71:05:91:00:d0:03:6a:f7:fd:08:00
>Mar 22 11:00:27 scorpio_1 kernel: NET: 4 messages suppressed.
>Mar 22 11:00:27 scorpio_1 kernel: martian source 10.1.12.151 from
>10.1.12.87, on dev eth1
>Mar 22 11:00:27 scorpio_1 kernel: ll header:
>00:e0:4c:71:05:91:00:d0:03:6a:f7:fd:08:00
>
>So, is there anything else I could try?
>
>TIA
> Jörg
>
>=====
>

-- 
Casey Carter
Casey@Carter.net
ccarter@uiuc.edu
AIM: cartec69

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