If you don't know about TCP, UDP hole punching, don't bid. If You have not done any P2P application then it is less likely you can do it successfully.
I need a proof of concept or working code for TCP and UDP hole punching.
Here is the scenerio.
(1) I have a central server X with public IP address.
(2) 2 clients (A, B) connect with central server from two different countries with private IP address which are behind Any type of firewall or router.
(3) Central server will pass the public IP of A to B, public IP of B to A.
(3) Server A will connect directly to Server B with the information it received from central server.
(4) A and B are connected and without any more help from they can communicate using TCP or UDP protocol.
(5) Able to send simple "hello message" and get a reply from other end.
Implements both protocol or at least TCP protocol.
Before any payment project should be successfully tested using clients which is behind firewall and located in different network.
Note if you dont have time not apply for job.