Port Forwarding Failure
A while back I had issues with IPv4 port forwards breaking, and I thought it was related to IPv6. It turns out it wasn’t, entirely… I spent some time with tcpdump on the Unifi USG, and determined that packets were in fact reaching the router (eliminating my ISP as a suspect, but they’re usually pretty good about that stuff anyway). The counters on the port forwarding rules showed that they weren’t being hit, and I couldn’t work out why.
On a whim, I decided to try dropping the pseudo-interface I set up to allow monitoring of the modem status, and port forwarding worked suddenly! I’m not sure why, there was no indication on the iptables counters that traffic was heading out there or anything… but anyway, here’s the commands I used to stop and restart it:
ifconfig eth0:0 down ifconfig eth0:0 192.168.0.2 netmask 255.255.255.0 up
This brought the interface back up, but port forwarding still works, so I guess I’ll just have to do that periodically if the port forwards fall over. :(