gateways not speaking to each other

celebnavin · 01-20-2009, 01:07 PM

hi frns
i hav two subnets in 172.20.1.0/24 and 172.16.1.0/24. i want that the host on both of these subnets can communicate to each other.
for the 16 pool the default gateway is 172.16.1.1 and for the 20 pool the default gateway is 172.20.1.1
i hav placed a system b/w these two subnets and hav 2 nic's installed on it and configured with 172.16.1.1[on eth0] and 172.20.1.1[on eth1] respectively.
i configured my iptables for it but the host from one pool refuses to communicate with other pool..
my distro is F8. plz help guys

acid_kewpie · 01-20-2009, 02:15 PM

have you enabled ip_forward?

celebnavin · 01-21-2009, 03:59 AM

sorry i forgot to mention ...

ip forwarding is enabled in the file /etc/sysctl.conf

MarioT · 01-21-2009, 04:16 AM

can you traceroute something and post results.

jbfuller3 · 01-21-2009, 07:21 AM

If you have IPTABLES set to log any of the DROPs, you could check that log (or set it to log the DROPs and check the log).

Also you could run tcpdump on both interfaces, while sending test traffic between the two networks and make sure you are seeing the traffic. It may be easier to analyze if you write it to a file and then read it.

tcpdump -i eth0 -w ./eth0.output.dmp
tcpdump -i eth1 -w ./eth1.output.dmp

Then 'tcpdump -r <file>' to read the files.