Something I don't quite understand

In peer-to-peer connection, in order to make calls from caller to callee, they have to use an IP address and port number. Signaling is TCP and RTP in fact is UDP. Regardless how many hops the packets may travel through, in packets from the caller, the destination IP has to be the callee's IP and the port number has to be the one where the callee's Skype client is listening on. If you can monitor the target caller's traffic, is that difficult to identify if the caller called the callee? The anonymous hops are just like routers. They forward packets but don't change the destination IP and port.In terms of identifying RTP packets, payload can be encrypted but the IP headers can not. In the bit 8~15 of an IP packet, it's the ToS field and usually is set in RTP packtes to avoid delay in transmission. This paper sorta uses this feature to identify the RTP packets.As for payload encrption, it is based on algorithm agreed on both sides. If the algorithm is changed or the keys are changed, any designed decryption is useless.

If SIP is used, it's peace of cake to trace calls.

所有跟帖： 

• that is the secrete of using anonymous network -德州老外- ♂ (1035 bytes) () 08/25/2006 postreply 13:46:57

• 回複：that is the secrete of using anonymous network -ohlalala- ♀ (1588 bytes) () 08/25/2006 postreply 16:32:33