1. Interface problem with multiple alias interfaces in same subnet
I have a redhat 7.3 linux box (redhat kernel 2.4.18-10 compiled with my own
settings) which for reasons I will not list here has 6 consecutive ips in a
/28 range on one interface, they are setup like this (real ips
eth0: 10.0.0.1 (Local Lan) (3com 3c980)
eth1: x.x.x.1 (3com 3c905b-tx)
The subnet mask on each interface is 255.255.255.240
The interfaces (and aliases) are configured on bootup, they were setup using
redhats network config tool.
I have noticed that the scripts set default route for each interface, so I
have lines in rc.local which removes the unnecessary duplicate default
First question does this all seem ok so far? It might seem a bit crazy to
want so many ips on the same box but I have my reasons, and they are
reasonable, I see no reason why this configuration should not work provided
all the daemons etc I want to run can be bound to specific ips/interfaces
which they can.
My problem is that single ip's (so far always aliases on eth1) randomly stop
working, for example if I try to ping a known good host using ping
<goodhost> -I x.x.x.3 ,. I get no response, I have used tcpdump to watch
what is happening and I think that on at least one occasion echo is sent,
and a reply is received, yet it seems the kernel does not parse the
responses, I see no errors in dmesg or anywhere else.
Getting the alias interfaces to work again usually requires downing them all
and bringing them back up again.
The alias interface which is the most troublesome seems to be the one which
is getting the most connections, the interface that I run sendmail on.
I usually have a extensive iptables firewall in place but I have run with
the system without this and the problem persists.
Is there a issue regarding multiple alias interfaces ? I have used shell
systems which have far more than I have (for irc bnc's), so I think it
Perhaps I should try a different network card?
Any suggestions appreciated, this seems rather strange and hard to debug to
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