4.3.9	STUN Server and Clients

STUN

STUN (Simple Traversal of UDP over NATs) is a network protocol designed to identify the existence and type of NAT firewalls and NAT routers and to traverse them. It is designed to facilitate the use of devices, such as, SIP phones and computer programs in home networks, that receive data from the Internet. The devices or programs connect to a STUN server and can then be accessed from the Internet without having to modify any firewall or router settings. The protocol was defined in the IETF's RFC 3489. STUN can also be used to determine the current public IP address of a port. It enables a SIP phone to determine and signal its currently valid IP address. This is necessary to ensure that remote stations can address their call data correctly.

HiPath 3000 STUN client

HiPath 3000 features a STUN client. The STUN client traverses the customer router's NAT.

Figure 4-2

STUN client

NAT

There are four types of NAT: Full Cone NAT, Restricted Cone NAT, Port Restricted Cone NAT, and Symmetric NAT. Only the first three NAT types work with STUN. The STUN protocol does not work together with a symmetric NAT implementation.

HiPath 3000/5000 V8, Feature Description, Issue 10		up
Disclaimer & Copyright	ID: P31003H3580F100017618	2011-02-07