ICMP redirects

ICMP redirects

Post by Alun Saunder » Wed, 04 Mar 1998 04:00:00


I have a Linux box set up as a default router to my Windows 95 machine. It
has a number of static routes defined as follows

Destination     Gateway         Genmask         Flags Metric Ref Use
Iface   U     0      0        9 eth0   U     0      0        0 eth1   UG    0      0        2 eth0       U     0      0        1 lo

The 192.168.3 subnet is reachable only via another machine (, a
Vines server !) that is also acting as an IP router.

On my Win'95 machine I see that I am getting ICMP redirects (presumably)
from the Linux machine which puts routes to the hosts on the 192.168.3 net
into my routing table. I would have expected these redirects to be subnet
redirects, but instead I am getting a new host route in my routing tables
for *every* host on the 192.168.3 subnet that I contact.

Am I missing something here or does Linux only do host level redirects ???

Alun Saunders
AMSYS, Veldhoven,  Netherlands


1. 1.3.x: ICMP redirect ignored, bug or feature ?

Since installing the 1.3.x kernels I get hundreds of messages in
/usr/adm/messages telling me that a redirect from our routers IP number
has been ignored by eth0 (the Linux 3com network card). I know that the 3com
router advertises itself as the default route on this segment but somehow
the new Linux kernels won't accept this ICMP redirection as of 1.3.x ??

W.R. de Kler

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