Multiple routing query

[Mike Harris]

Hello,

Am writing to the list in the hope that someone out there might be able
to help me make sure I have the right configuration here. I'm not all
that au fait with routing using multiple interfaces.

Some time ago I configured a web server to have two different IP
addresses from two different network ranges on each of it's two ethernet
cards.

I followed the excellent instructions at
http://lartc.org/lartc.html#AEN268 and came up with the following
configuration:

#!/bin/bash
/sbin/ip route add 194.164.97.0 dev eth0 src 194.164.97.252 table T1
/sbin/ip route add default via 194.164.97.1 table T1
/sbin/ip route add 86.54.82.144 dev eth1 src 86.54.82.146 table T2
/sbin/ip route add default via 86.54.82.145 table T2

/sbin/ip route add 194.164.97.0 dev eth0 src 194.164.97.252
/sbin/ip route add 86.54.82.144 dev eth1 src 86.54.82.146

/sbin/ip route add default via 194.164.97.1

/sbin/ip rule add from 194.164.97.252 table T1
/sbin/ip rule add from 86.54.82.146 table T2
/sbin/iptables-save

I'm uncertain if the last line is actually needed there.

My understanding is that what is supposed to happen is that incoming
traffic to 86.54.82.146 is correctly routed back through the same
interface to the gateway at 86.54.82.145 and similarly traffic to
194.164.97.252 is routed back through 194.164.97.1.

I test this using ping but it doesn't seem to work properly, whichever
interface is set as the default route becomes just that. So 'ping -I
eth0 lartc.org' works but 'ping -I eth1 lartc.org' doesn't.

I've checked to make sure the kernel has the compile parameter
IP_MULTIPLE_TABLES in it and it does.

So I cannot work out where I've gone wrong. I've trawled back over the
LARTC HOWTO and can't spot anything else.

Can anyone help with this, or at least give me some pointers on things
to try?

Thanks in advance,

Mike.
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Mike Harris
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[Peter Rabbitson]

Post by Mike Harris
I test this using ping but it doesn't seem to work properly, whichever
interface is set as the default route becomes just that. So 'ping -I
eth0 lartc.org' works but 'ping -I eth1 lartc.org' doesn't.

The source selection code of the ping binary is broken. Try
-I 86.54.82.146
as the source argument and watch your pings fly away.

HTH

Peter

[Mike Harris]

No way!!!

Thanks Peter, I have a feeling this means that I was stumped by what I thought
was the simplest and most failsafe program to test network connexions around.

I never ever even thought of checking that ping might not be behaving itself.
Doh! This means (I think) that it was working all along.

Many thanks for that again Peter,

Mike.

Post by Peter Rabbitson

Post by Mike Harris
I test this using ping but it doesn't seem to work properly, whichever
interface is set as the default route becomes just that. So 'ping -I
eth0 lartc.org' works but 'ping -I eth1 lartc.org' doesn't.

The source selection code of the ping binary is broken. Try
-I 86.54.82.146
as the source argument and watch your pings fly away.
HTH
Peter

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Mike Harris, Psand
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Fax: [phone]
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