CommuniGate Pro supports various real-time communications. Most of those real-time protocols cannot be used via a NAT/Firewall, so CommuniGate Pro can act as "proxy" for those protocols.
When a client on the LAN tries to communicate with a remote system on the Internet (WAN), CommuniGate Pro creates a Media Proxy - a communication port on its own system. It forces the client to connect to that Media Proxy instead of the remote system media port. The CommuniGate Pro Media Proxy communicates with the remote system itself, relaying the data received from the LAN client to the remote system and vice versa.
A Media Proxy is created to serve entries (users) located behind remote NAT devices.
A Media Proxy is created to relay traffic between an IPv4 and IPv6 entries.
Log: Use this setting to specify what kind of information the Media Proxy component should put in the Server Log. Usually you should use the Major or Problems (non-fatal errors) levels. But when you experience problems with the Proxy component, you may want to set the Log Level setting to Low-Level or All Info: in this case protocol-level or link-level details will be recorded in the System Log as well. The Media Proxy component records in the System Log are marked with the MEDIAPROXY tag. A Media Proxy can create zero, one or several stream proxies for each media stream (for example, one stream proxy for the audio stream, and one - for the video stream). Stream proxy records in the System Log are marked with UDPPROXY or the TCPPROXY tag.
Source Port Restriction: When this option is selected, the UDP-based media from external non-NATed sources is accepted only when it comes from the correct IP address and port number. When this option is not selected, only the media source IP address is checked. This helps to serve certain broken devices that send SDP data with incorrectly specifed media port numbers.
UDP TOS Tag: Unless this option is set to OS default, the UDP-based media packets get the specified TOS (type of service) tag value. This may help you prioritize the media traffic if your network infrastructure assigned a higher priority to packets with the specified TOS tag. Relay for clients behind the same NAT When two endpoints are located behind the same far-end NAT (i.e. when their visible, external Network IP Addresses are the same), this option specifies if a Media Proxy should be built to relay media between these endpoints.
Never: Media Proxy is not built for these endpoints. Use this option when you expect that endpoints behind the same NAT IP can communicate directly.
NAT Sites: Media Proxy is built for these endpoints if their visible Network IP Address is included into the NAT Server IP Addresses list.
Always: Media Proxy is always built for these endpoints.
Note: some remote NAT systems are "multihomed". In this case, a signaling request can come from one external IP Address of that system, while the m