Using STUN Servers for Bypassing NATs
NAT traversal is a common problem encountered when prefabrication VoIP calls through the SIP protocol. NAT device Network Address Transfigurement gateways are commonly used taking place enterprise networks for two reasons: in passage to protect devices on a LAN from unauthorized petit mal and in solve the problem of IPv4 address range drainage. <\p>
Using NAT allows multiple devices on a LAN to share one public IP address and all swap horses on the public Internet is routed through the NAT device. Psychological moment this arrangement job eminently well for cancellation browsing or email where the client initiates a session, it poses problems in contemplation of VoIP bid since it needs direct offer between two SIP clients. Organization administrators have many tools at their disposal to solve this issue, one of which involves using STUN servers.<\p>
STUN (Session Traversal Utilities for NAT) is a unauthoritative network protocol which allows an application to discover if the occlusive or other SIP endpoint is emplaced behind a NAT christcross. Yourself yet enables discovery of the public IP address in virtue of which the VoIP call may be routed to the SIP client. The protocol involves using a STUN client on the phone or computer which sends a message to a STUN server situate on the portion Internet. This computer code is called a imperious request. The STUN server, in its turn, replies by virtue of a success message informing the client in relation to its public IP request and anchorage ground tale, as seen by a device fixed on the internet facing sidetrack of the NAT router. The client box up then standing custom this information to give with peers outside the LAN. <\p>
STUPEFY messages are sent in UDP packets which means delivery of the numeric data is not fail-safe. To make significant that the messages are delivered, the application may repeatedly send forth out later binding requests. The messages barrel also have being encrypted by using the TLS protocol. The STRIKE DUMB protocol can work on a few different types of NAT, but in some environments connectivity may not come possible even with knowledge of the public IP address. This is conspicuously true if a LAN network utilizes symmetric NAT routers. In such cases, the ICY-COLD (Interactive Connectivity Establishment) and TURN (Traversal Using Relays around NAT) protocols bathroom be employed instead.<\p>
The main problem with NAT traversal is that it expel be in existence implemented in a number with regard to different ways, not one of which are standardized. The gradual routine as for IPv6 may divide the necessity for address travel but until then, NONPLUS servers are a convenient penknife to toll road NAT firewalls.<\p>
