[SOLVED] Firewall and VOIP

Question

Hi I am running a simple firewall on my laptop configured using ufw.
Now I was trying to set up my new SIP account in linphone. It works just fine except when I receive calls - I get no audio in. This is what I know so far:
1. Not a NAT problem, works fine via my phone setup on the same LAN.
2. No new new entries in /var/log/iptables.log - I opened port 5060 for udp and 7078 for udp and tcp. (linphone wants rtp on 7078 I believe)
3. It starts working fine, if I open all ports via, "ufw default allow".
How do I find which port it is that I need to open for this work?
Help is appreciated. Thanks.
Last edited by lamdacore (2012-09-02 19:46:32)

Answer 1

Add an explicit LOG rule at the start of INPUT to just log all incoming traffic, then examine those logs:
iptables -I INPUT -m state --state NEW -j LOG --log-prefix='[NEW]'
iptables -I INPUT -m state --state RELATED -j LOG --log-prefix='[RELATED]'
While a call is in progress (with the firewall disabled), you could also examine the output of netstat:
netstat -tunp | grep program
Replace "program" above with whatever application you're using so you only see the connections that process has open.