Ping does not respond after 8 or 9 successful replies.

Today I had an interesting issue on Ubuntu 8.10.

We have 2 NICS on the server one has the following ip 172.16.20.10/16 and another one has 172.16.60.10/16. I know they are on the same network though but we had to do it in order to accomplish some routing issues.

So here is the problem:
When I try to ping our ISPs Gateway it succesful pings till the eighth or ninth reply and stops replying.
On ubuntu 6.10 it works fine.

So here is the solution:

Since we have 2 NICs with the same network address when the second one tries to reach a remote server the Kernel thinks it is a spoofing attack since by default it is enable source address verification against spoofing attacks.
So what you have to do is to change the rp_filter kernel parameter to 0 (zero).

1. Edit 10-network-security.conf
vi /etc/sysctl.d/10-network-security.conf
change to 0 (zero)
2. invoke-rc.d procps start

This is it!

Leonardo