Redhat/OSPF routing issues

[ron fisher_1]

Greetings fellow linux fans

background: I run a big brother network monitoring system on RH 8.0. It works extremely well for monitoring all of our windoze servers, routers etc. It pings each host approximately once every 5 seconds or so. We also monitor our routers spread across a private Frame network. The frame PVC's are backed up by ISDN circuits with auto-failover. I ping the ethernet interface on the router from big brother. We use OSPF as the routing protocol.

When a frame circuit goes down (usually in the middle of the night, making it hard to test!) the RH box immediately re-routes to the only other open path, the Internet where it fails.. the ISDN comes up I would believe AFTER the RH box has re-routed. RH ping keeps failing and won't re-route to the ISDN or back to the Frame when it comes back up. I have to reboot the RH box in the morning to get it to route properly. Tried IFCONFIG down/up but that doesn't work.

Anybody have any similar experience? I know RH likes to play games with Pimg and am wondering if it is RH ping, OSPF or both..

Thanks.

[Stuart Browne · Accepted solution]

Just wondering, have you left your RH8 box accepting "IP Redirects" ?

To check, do the following:

cd /proc/sys/net/ipv4/conf
cat */accept_redirects

If you get a whole list of 1's, then you are still accepting IP redirects (which are an ICMP request to say "oh, it's easier to get to that host by going this direction").

For some reason, these IP Redirections don't show up in the routing table in RH8 (most frustrating), and thus make it hard to remove.

Put this in the bottom of your /etc/rc.d/rc.local file, and see if the problem persists:

for TOUCH in /proc/sys/net/ipv4/conf/*/*redirects
do
echo 0 > $TOUCH
done

This will turn off 'accept_redirects', 'send_redirects', and 'secure_redirects', the three annoyances on a network with real routing.

See if this helps you.

[ron fisher_1]

Yes it is doing exactly that. I put the script in place and will let you know how it goes.

I wish RH would stop fussing with core network components. I have several hacks in place just to counter what they do to things like PING.

Thanks for the reply and the detailed help!!!

[ron fisher_1]

Haven't confirmed completely that this was the issue, but I wanted to give you your deserved points for a very helpful and detailed response to an issue that has been bugging me for a long time. It amazes me everyday how much there is to learn about networking. It is so helpful to have active forums like this to colaborate and further the world of IT and networking.