The Issues of Firewall/NAT Traversal: The aim of a firewall is to confirm that solely licensed users are allowed Access. Nowadays, most homes possess a firewall-protected association through cable or ADSL.
Enterprise or home users who are protected behind their own firewall are Communicating from what we tend to call an indoor network. The user's endpoint communicates with a gatekeeper via the Net through a firewall or a NAT (usually both) to another endpoint. The gatekeeper and the other endpoint are on what we call an external network. When the opposite endpoint is on a different internal network, it ought to conjointly use an identical resolution to traverse through its own firewall/NAT.
For that video communication we have a tendency to are going to user RTP,RTSP etc Protocols. These protocol are used to transmit the audio, video for A to B.
RTP is unidirectional
-A indicates IP/port to receive from B
- B indicates IP/port to receive from A
- If either is behind NAT, media will not flow to them.
Therefore we have only achieved the point to purpose Audio, Video transmission using RTP Streaming Protocol. In the case If we tend to want to send behind NAT, Solution: make RTP appear as if client-server protocol
- A indicates IP/port to receive from B
- B sends to A, A sends back to B using supply IP/port of RTP
- Primarily, solely want IP address from ONE of the participants - the "server"
For our net primarily based application, a while the presenter (A) or Consumer (B) may be use the Proxy server setting to access the Internet. So we have a tendency to want the answer for Transmitting Audio, Video - (using of Streaming Protocol) and Knowledge - (TCP, UDP protocol) over NAT, Firewall.
To achieve the NAT Traversal there features a two simple algorithm, that are fashionable
one) STUN - Simple Traversal of UDP (User Datagram Protocol) through NATs (Network Address Translators)
two) TURN - Traversal using Relay NAT
3) Universal Plug and Play (UPnP)
four) Application Layer Gateway
5) Tunnel Techniques
vi) Automatic Channel Mapping(TM) (ACM)
seven) Manual Configuration
In the On top of strategies the STUN is the most effective methodology of solving NAT. The is a API known as STUN in JAVA.This can facilitate us to Solving of NAT Traversal Problem. STUN could be a consumer-server protocol. A VoIP phone or software package may include a STUN shopper, which can send asking to a STUN server. The server then reports back to the STUN client what the public IP address of the NAT router is, and what port was opened by the NAT to allow incoming traffic back in to the network. The STUN algorithm as follows,
For that Video, Audio Transmission we would like the streaming Server like Microsoft, Real Media, Apple Quick Time, Flash Media server, etc. The most reason for using Steaming server is Transmitting and receiving for RTP Stream Data. For Transmission of Knowledge we tend to use the TCP or UDP Sockets.
The IP based mostly voice and multimedia services as major half within the Web traffic. Unfortunately, a number of technical problems are having. The foremost significant of these is to supply secure association to subscribers behind NAT (Network Address Translation) devices and Firewalls.