nathelper is a module to help with NAT traversal. In particular, it helps symmetric UAs that don't advertise they are symmetric and are not able to determine their public address. fix_nated_contact rewrites Contact header field with request's source address:port pair. fix_nated_sdp() adds the active direction indication to SDP (flag 0x01) and updates source IP address too (flag 0x02). Alternative solution for NAT traversal in OpenSER is mediaproxy module.

You need to run rtpproxy to get NAT traversal along with nathelper module.

When configuring nathelper pay attension at setting control socket for media proxy.
In difference to rtpproxy control socket for nathelper it is a socket for MEDIAPROXY, not for DISPATCHER like in rtpproxy.

Links to documentation of nathelper module:

• nathelper module for openser 1.0.x
• nathelper module for openser 1.1.x
• nathelper module for openser 1.2.x
• nathelper module for openser devel

See also:

• OpenSER+and+Mediaproxy - OpenSER configuration to do NAT traversal using mediaproxy
• OpenSER+and+RTPProxy - OpenSER v1.1.x configuration to do NAT traversal using nathelper and rtpptoxy
• OpenSER+v1.2.x+and+RTPProxy - OpenSER v1.2.x configuration to do NAT traversal using nathelper and rtpptoxy