pfSense

My Asterisk PBX periodically loses contact with my VoIP provider until I reboot pfSense. The symptoms are that the PBX sends SIP packets to the provider (to UDP/5060) and receives no reply.

My WAN port is PPPoE.

Today I used pfSense's packet capture to look at the WAN traffic and noticed that the source IP on the outbound SIP traffic was not the same IP assigned to my WAN port through the PPPoE connection.

Oddly enough HTTP, HTTPS, etc. work - this issue may be specific to UDP NAT.

At the time of testing, my WAN IP was 76.70.78.39 and DNS traffic originated from that address (DNS forwarding by firewall). SIP traffic was being sent out the WAN port with a source address of 70.26.17.101 and obviously the reply from my provider would not reach me...

Here's a sample from the packet capture:

15:26:27.362746 IP 76.70.78.39.47996 > 8.8.8.8.53: UDP, length 37
15:26:27.394311 IP 76.70.78.39.57506 > 208.67.222.222.53: UDP, length 37
15:26:27.394360 IP 76.70.78.39.57506 > 208.67.220.220.53: UDP, length 37
15:26:27.398788 IP 8.8.8.8.53 > 76.70.78.39.47996: UDP, length 317
15:26:27.433899 IP 208.67.222.222.53 > 76.70.78.39.57506: UDP, length 317
15:26:27.436833 IP 208.67.220.220.53 > 76.70.78.39.57506: UDP, length 317
15:26:27.989333 IP 70.26.17.101.13861 > 184.75.215.146.5060: UDP, length 403
15:26:28.024769 IP 70.26.17.101.12336 > 208.100.39.55.5060: UDP, length 403
15:26:28.053295 IP 70.26.17.101.25796 > 72.55.168.18.5060: UDP, length 396
15:26:30.489465 IP 76.70.78.39.52792 > 208.67.222.222.53: UDP, length 34
15:26:30.511068 IP 208.67.222.222.53 > 76.70.78.39.52792: UDP, length 50
15:26:30.511438 IP 70.26.17.101.13861 > 184.75.215.146.5060: UDP, length 403
15:26:30.525410 IP 76.70.78.39.59911 > 208.67.222.222.53: UDP, length 34
15:26:30.571651 IP 208.67.222.222.53 > 76.70.78.39.59911: UDP, length 50
15:26:30.572042 IP 70.26.17.101.12336 > 208.100.39.55.5060: UDP, length 403