How to enable RHEL two interfaces ? Or why does RHEL ignore packets when the route for outbound traffic differs from the route of incoming traffic?

 

• Why does Red Hat Enterprise Linux 6 invalidate / discard packets when the route for outbound traffic differs from the route of incoming traffic?

Resolution

Set the net.ipv4.conf.all.rp_filter kernel tunable parameter value to 2:

Raw

sysctl -w net.ipv4.conf.all.rp_filter=2

To make this change persistent across reboots, add the tunable to the /etc/sysctl.conf file.

Enjoy :)