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Old 2nd August 2011, 17:43
johncongdon johncongdon is offline
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Default IPTables Masquerading Issue

I have setup masquerading dozens of times with no issues.

I have 2 linux boxes (A=Private, B=Masquerader)

Here are the checks I have done
A - Default gateway is B
B - iptables is wide open with 1 postrouting statement
iptables -t nat -A POSTROUTING -s -j SNAT --to-source PUBLIC_IP
B - IP Forwarding is enabled.

I can ping from A to B's private address. Cannot go past that.
If I run iptraf on B, I can see the ping req/reply from A to another IP.

If I ssh from A to another machine outside the firewall, I can see the connection attempt with netstat -an | grep :22 on the remote machine.

So the connection are being transmitted out correctly, but not getting returned correctly through SNAT. Any ideas?
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