How can two different hosts with different public IP can communicate through sockets? [C programming]

Question

I'm trying to make a communication between two different hosts (using two different computers in my University). I saw that we only can bind to the socket local IP addresses . So how can I make a communication client/server just by knowing the ip public addresses of the two hosts?

PS: I can't have access to the local ip address of the computer of my university. Maybe for security reasons... And a ping between the two hosts with their public ip works properly.

Answer 1

You can not connect to the other host without tweaking the router.

[Host A Client] -- [Router A] -- (Internet) -- [Router B] -- [Host B Server]

Router B needs to know how to forward incoming packets to Host B , it's done by one of the following:

• Demilitarized Zone
• Static port forwarding
• Dynamic port forwarding
• Universal Plug & Play (NAT-PMP)