[asterisk-users] conntrack_sip, iptables, and asterisk

Alex Balashov abalashov at evaristesys.com
Wed Oct 8 21:57:41 CDT 2008


The problem is that the Linux SIP ALG is not RTP-aware and doesn't NAT 
the RTP.  If that's changed, it would have to be in the last one or two 
kernel releases.

Your solution is OpenSER (Kamailio/OpenSIPS) + nathelper + mediaproxy or 
rtpproxy.

OCG Technical Support wrote:

> I have a new Fedora 9 firewall I am setting up in front of an Asterisk 
> 1.4 box.  I ported over all of my iptables rules..but now have a strange 
> problem:  SOMETIMES, the audio is only 1-way (i.e. and RTP path problem).
> 
>  
> 
> Can someone offer a tip here?  Since I have conntrack_sip loaded on the 
> firewall, do I need to:
> 
>  
> 
> 1.      Use SIP and RTP port forwarding & prerouting to my asterisk 
> box?  (SIP clients are outside the LAN) – this is the way I do it now
> 
> 2.      Remove all SIP and RTP port forwarding & prerouting and assume 
> conntrack_sip will do everything?
> 
> 3.      Allow SIP and RTP **INTO** the firewall, to allow conntrack_sip 
> to work?
> 
>  
> 
> Clearly something has changed with conntrack_sip or iptables in the 
> latest kernel...so I need to figure this out.  Help!
> 
>  
> 
> Thanks!
> 
>  
> 
> Michelle
> 
>  
> 
>  
> 
> 
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> 
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-- 
Alex Balashov
Evariste Systems
Web    : http://www.evaristesys.com/
Tel    : (+1) (678) 954-0670
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