Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I want to forward all GRE traffic (IP protocol 47) coming on eth2 to br0 on my machine. How can I do that?

share|improve this question
up vote 1 down vote accepted

I've never tried it, but first you need to match the traffic you want. You should be able to do so using iptables and the -p option with the protocol number:

PARAMETERS The following parameters make up a rule specification (as used in the add, delete, insert, replace and append commands).

   [!] -p, --protocol protocol
          The  protocol of the rule or of the packet to check.  The speci‐
          fied protocol can be one of tcp, udp, udplite,  icmp,  esp,  ah,
          sctp  or  all, or it can be a numeric value, representing one of
          these protocols or  a  different  one.   A  protocol  name  from
          /etc/protocols  is also allowed.  A "!" argument before the pro‐
          tocol inverts the test.  The number zero is equivalent  to  all.
          Protocol  all  will  match  with  all  protocols and is taken as
          default when this option is omitted.
share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.