I was posting linux-kernel about my linux box not learning from icmp
redirects and i was advised to see into my configuration, but today
i found that the problem is within netfilter code.
Here is the scoop:
In a nutshell:
- iptable_nat, _may_ cause the box to ignore icmp redirects (maybe other
Host A is in a network where there is router B and router C.
Router B routes to other networks.
Router C routes to the Internet.
Host A's routing entries:
- to its network
- default via router B
When host A with this module loaded communicates with the world,
after some time the rate of icmp redirects from router A for packets to
the Internet rises enormously. Normally the host should react to the first
packet and then send all the packet through the advised router, ie. B.
The way i reproduce this bug:
# insmod ip_tables
# insmod ip_conntrack
# insmod iptable_nat
Now wait some time. After a few minutes i see in iptraf
that ICMP rate is rising, the icmp i get is about 30% of all the TCP
Now i remove the iptable_nat
# rmmod iptable_nat
The rate of icmp suddenly drops, as seen on iptraf stats. The rate is
less than 0.1% of all tcp traffic.
This is a 2.4.20-xfs kernel with the following patch-o-matic patches:
Already applied: submitted/01_2.4.19
I can supply any information required to pursue this problem.
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