Your system may have a firewall that prevents GRE transmission. The GRE-to-PPP gateway sends the packets, but they are dropped by the packet filter before being transferred to the interface.

I dont know how to fix this if you are on windows


on linux or bsd you can add the following

You will have to check your firewall rules, remove or add replacements, and try again. The following iptables rules may be added to allow GRE through eth0. Change eth0 to the name of the interface if needed


iptables --insert OUTPUT 1 \
--source 0.0.0.0/0.0.0.0 \
--destination 0.0.0.0/0.0.0.0 \
--jump ACCEPT --protocol gre \
--out-interface eth0

iptables --insert INPUT 1 \
--source 0.0.0.0/0.0.0.0 \
--destination 0.0.0.0/0.0.0.0 \
--jump ACCEPT --protocol gre \
--in-interface eth0

These rules can be refined further to constrain the GRE traffic.


S3C
www.sec-net.tk