Gre Tunnel Cisco Linux traffic forwarding

Posted by mezgani on Server Fault See other posts from Server Fault or by mezgani
Published on 2011-10-03T04:12:51Z Indexed on 2014/06/07 3:32 UTC
Read the original article Hit count: 534

Filed under:

linux

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iptables

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cisco

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tunneling

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gre

I setup a gre tunnel a cisco router and a Linux machine, the tunnel interface in the Linux box named pic. Well i have to forward traffic coming from cisco through the Linux box. the rules i've set in the Linux box is described as follow:


echo "1" > /proc/sys/net/ipv4/ip_forward
iptables  -A INPUT -p 47 -j ACCEPT
iptables  -A FORWARD -i ppp0 -j ACCEPT
iptables  -A FORWARD -i pic  -o ppp0 -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables  -A FORWARD -i ppp0 -o pic -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables  -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE

I see the traffic coming from tunnel and forwarded to internet but no reply from sent packet.

May i miss something like a routing rule.

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