Interesting network issue...or not
I have an interesting issue.
I have a Redhat 9 shrike machine that needs to be upgraded so I loaded the latest Fedora and Debian and both have the same issue. What happens is that the AT&T VoIP router fails to receive incoming audio packets. As a matter of fact I don't see them even on the Linux external interfaces either. HTTP traffic from the internet is fine. DNS is fine too.
Here is the configuration of the network.
internet -> pppoe -> eth2 ->linux -> eth0-> AT&T-dlink-router
I have snooped the ppp and eth0 interfaces and cannot see any UDP port 10k-11k packets coming from AT&T.
I plug the original hard drive in and reboot and everything works fine and I see bidirectional VOIP traffic.
I am building my iptables rules using fwbuilder in both cases. The policy when I test the VOIP connection says any-any-allow and the nat rule says src = internal_net translated-src = ppp0
As near as I can tell the rules and definitions are identical on the old and new system.
So, what would prevent me from seeing the port 10k UDP packets on my external facing ppp0 or eth2 interfaces?
With logging turned on i see no allows or denys for this UPD traffic that I assume is headed my direction but cannot see.
tcpdump says there are no packets coming in either.
I am missing something. What is it?