Netfilter RTP Proxy
The netfilter xtables module called xt_RTPPROXY enables connecting two RTP/RTCP clients where at least one is hidden behind the NAT and have no public IP address. It's primary intended for VoIP telephony driven by SIP. High level SIP router demands a RTP session and passes parameters of allocated session to VoIP clients in SDP. Clients will send all media streams, i.e. UDP packets, to proxy with public address and RTP proxy will pass data to opposite client. Userspace manipulation library libipt_RTPPROXY for both iptables and 3rd party application is included. Command line utility for RTP session manipulation iptrtpproxy is implemented as well.