User manual

得伯乐科技有限公司
DBL Technology Limited GoIP User Manual
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3.5.6.3 Media NAT Traversal
The media NAT (firewall) traversal is classified into four types:
A. No firewall
The firewall traversal mechanism is not supported.
B. Port Transparency/DMZ
The port transparency is used to transfer the network port on the LAN interface to the computer
or the server in the LAN. This feature enables external users (through the Internet in most cases) to
share the services of internal servers (such as FTP, HTTP, and Telnet).
The port transparency supports the address of the gateway and response server. The gateway is a
communication device that connects two different networks. The response server is a standard service
device that implements the ECHO protocol.
C. STUN (RFC 3489)
The Simple Traversal of UDP over NAT (STUN) is a protocol that enables the SIP telephone to
detect the existence and type of the firewall installed in the computer. This parameter indicates the
SIP address of the STUN server.
Note: The STUN protocol supports the SIP gateway only.
D. Trunk Agent
The trunk agent protocol is a firewall traversal technology developed by DBL Technology. It
enables the products of DBL Technology to be applicable for most LANs. It involves the address, port,
user name and password. The trunk agent protocol supports encryption on communications over the
gateway. This feature needs the support of the server developed by DBL Technology.
Media agent mode:
Mode 1: media encryption and agent (supported by all versions of relay servers).
Mode 2: media encryption and agent, supporting the transit over the specified port
(supported by V2 relay server).
Mode 3: media encryption and agent for the conversion of RTP data to TCP packet,