changing the source address of an ICMP TTL exceeded message

Guy Antony Halse g.halse at
Sun Feb 8 23:10:17 PST 2004


I've got two FreeBSD routers that act as redundant backups of each other
using VRRP.  Both these machines bind their own interfaces for
administration purposes and the VRRP handles which one binds the gateway

My problem is that, because the admin interface is bound before the gateway
one, when I traceroute through the router I see the address of the admin
interface rather than the gateway.

So what I need to do is change the source address in the ICMP TTL exceeded
messages that get sent out from the router to the gateway address.  vrrpd
lets me execute arbitary scripts when it becomes master/slave, so this
shouldn't be a problem.

The question is how do I actually change the source address?

- Guy
Systems Manager, IT Division, Rhodes University, Grahamstown, South Africa
Email: G.Halse at   Web:  IRC: rm-rf at
*** ANSI Standard Disclaimer ***                                   J.A.P.H

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