Iptables – Workaround for blocking SIP port (5060) by ISP

forwardingipiptablessip

I found out my ISP is blocking outgoing SIP port (5060) at home. I have a remote Linux server that I can use to listen on different port than 5060 and do the forwarding for the traffic. Not sure what iptables rules needs to be applied to make things work.

Is there a need to do the forwarding for RTP ports (10000-20000)?

Your help is appreciated.

Thanks.

Best Answer

Can you run a SIP proxy on your remote machine, say on 15060? Then you can set up your local SIP user agent to use that machine. Signalling traffic from your SIP UA goes out on 15060, and incoming calls will route through your proxy.

You wouldn't have any additional need to forward RTP with the above setup, but you might still need to work around your NAT if you have one.

Related Solutions

Iptables – How to configure vsftpd and iptables to listen on port 21 but run on another port

I think what you are looking for is REDIRECT:

iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 21 -j REDIRECT --to-port 20000

And you need to use passive-ftp.

Cisco ASA 5505 – NAT or Port Forward for SIP / VoIP ver 8.4

You don't have to explicitly forward RTP ports (>1024) as you have sip inspect turned on. When a SIP INVITE comes through, the router will open the appropriate RTP ports for the duration of the call.

As far as NATing SIP, you are missing the NAT command, and the access-list entry:

! this should be tightened to allow traffic only from your telephone company, or 
! people with bad intent will happily place international calls on your account
access-list outside_access_in extended permit udp any host 192.168.3.150 eq 5060 
! nat 5060 to 5060
object network NEC_DSX
 nat (inside,outside) static interface service udp 5060 5060

Though it is not needed, the proper syntax to forward a range is:

object service rtp-1024-1215 
 service udp source range 1024 1215
object network NEC_DSX_RTP
 host 192.168.3.150
 nat (inside,outside) static interface service rtp-1024-1215 rtp-1024-1215

Best Answer

Related Solutions

Iptables – How to configure vsftpd and iptables to listen on port 21 but run on another port

Cisco ASA 5505 – NAT or Port Forward for SIP / VoIP ver 8.4

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