At 13:28 08.05.2000 +0200, Richard Jørgensen wrote:
>> perhaps someone could update me, how a Linux kernel select the source IPv4
>> address on ICMP/UDP.
>
>I haven't read the kernel source, but I might be able to help anyway.
>
>> One PC with one Ethernet interface
>>
>> Basic IP is:
>> eth0: x.y.z.62
>> Also I defined some aliases:
>> eth0:0 x.y.z.61
>[...]
>> ping [...] should have source IP address of "eth0" (*.62).
>
>My experience with using aliases is that the source address is based
>on the routing table:
>"route add -host x.y.x.t" will cause "ping x.y.z.t" to have source
>address x.y.z.62 whereas
>"route add -host x.y.x.t dev eth0:0" will cause "ping x.y.z.t" to have
>source address x.y.z.61
>
>The aliases you create will automatically be added to the routing, so
>if you use several ip-adresses belonging to the same net, pinging a
>host on that net will use the last alias you defined as source address.
>
>Note: The routing table will show Iface = eth0 regardless of whether
>it is eth0, eth0:0, eth0:1, ...
Good hint, this solved the problem.
You're right, I got about 4 default route entries after setting 1 basic and
3 alias IPs.
If I've removed 3 of them, the first IP address set (eth0) is used on
outgoing packets.
Because of on 2 other similar RedHat 6.2 installations this won't occur,
I've looked for diffs and found one:
/etc/sysconfig/network
must contain:
GATEWAYDEV="eth0"
Afterwards, only one default route is set up, not per each alias.
Thanks for helping!
Peter
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