AEQ
TALENT
71
B5. STUN protocol.
STUN
(
S
imple
T
ransversal of
U
DP over
N
ATs) is a network protocol of the client /server type
that allows NAT clients to find their public IP address, the type of NAT where it is located and
the Internet port associated with the local port through NAT. This information is used to
configure a UDP communication between two hosts located behind NAT routers.
NAT (Network Address Translation) is a mechanism used by IP routers to exchange packets
between two networks that assign each other incompatible addresses. It consists of converting,
in real time, the addresses used in the transported packets. It is also necessary to edit the
packets to enable the operation of protocols that include address information within the protocol
conversation. It is most commonly utilized to enable the use of private addresses and still
provide connectivity with the rest of the Internet.
TALENT includes a STUN client that sends a request to a STUN server. The STUN server then
informs the client of its public IP and which port has been opened by NAT to permit incoming
traffic to enter the client’s network. This information enables the Phoenix ALIO to identify its
position within the SIP server. This protocol is used in "AUTO3" and "AUTO4" NAT
TRAVERSAL modes (see section 4.3).
Registration in a STUN server
