Strange behaviour: Some traffic NATing to public IP address

siili

Hello,

I rebooted a router (was up for about 250 days) and the IP phones in the office will no longer work. On closer examination, I found all other traffic across the OpenVPN connection works as it is supposed to, but the SIP traffic on UDP port 5060 gets its source address translated right before going into tun0. The NAT address is the public IP address. Since this router is on Internet, there is no need for NAT. Also, that traffic does not make it through the tunnel. What is more bizarre is probes with nmap on UDP port 5060 work as expected from source, through the tunnel, to the destination. The only difference I see with tcpdump in the traffic (nmap vs. IP phone) is the packet size of the nmap generated probes are zero. I have cleared IPTABLES rules with no effect. I have restarted OpenVPN on both ends. This has me stumped. Any suggestions appreciated.

Regards,
David Koski
david@kosmosisland.com

siili

Thank you much.

debbie10t wroteDavid, some configs and logs would seriously help . . .
https://forums.openvpn.net/post33633.html

crystal ball on standby :ugeek:

I did get the SIP traffic to work but it just adds to the mystery. By changing the IP addressing in the phones from DHCP to static, now they work normally. I don't see anything different or interesting in the logs but the config file follows:

client.conf:

client
dev tun0
proto udp
remote 74.85.50.170 1194
resolv-retry infinite
nobind
persist-key
persist-tun
ca ca.crt
cert client.crt
key client.key
ca /etc/openvpn/keys/ca.crt
cert /etc/openvpn/keys/office14.crt
key /etc/openvpn/keys/office14.key
ns-cert-type server
comp-lzo
verb 3

Regards,
David Koski
david@kosmosisland.com