Failing virtual interface, please help

From: Marv (marv_at_somewhere.com)
Date: 02/28/04 

Date: Sat, 28 Feb 2004 17:46:23 GMT

I'm using RedHat 9.0 and have setup iptables as a firewall/nat. On this
particular server, there are two virtual interfaces in addition to the main
WAN IP. On one of the IPs, I'm forwarding port 80 to an internal address.
I'm having a very strange symptom. It will work for a little while and then
when you try to hit this IIS 5.0 website (which uses NTLM authentication),
it fails...you just get the white screen in your browser. If I issue an
'ifdown eth0:2' and then 'ifup eth0:2', the website starts working again for
a while but eventually it happens again.

Here is the setting for the virtual interface:

DEVICE=eth0:2
BOOTPROTO=static
IPADDR=63.xx.xx.xx
NETMASK=255.255.255.252
ONBOOT=yes

Here is part of the iptables script:

iptables -A PREROUTING -t nat -p tcp -d $ext_if2 --dport 80 -j DNAT --to
192.168.168.117:80

The funny thing is that I'm also forwarding port 23 via a different virtual
interface to a different internal server, and it never seems to fail.

Does anybody have any suggestions for this issue?

Thanks,
Marv

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