Can't receive UDP Datagrams

Question

i have to develop a distributed system that consists in having a chat session by TCP sockets with someone from it's IP address, connected to a server that lists all ips connected for the last 3 minutes to it. alongside with this main feature the app must make requests to every ip to get their name and current state, active, busy or stopped. after sending that request over UDP sockets and, in the other side they must send a reply of that request also over UDP.

EDIT - basically, the application must contact a server that stores the ips that connected to the server for the last minutes. then it must retrieve that ip addresses and contact each one to get it's name and status.

unfortunately i only receive my reply to my request but the other colleagues receive my request.

how can i fix this situation?

Answer 1

You haven't given us much information to go on, but my first thought would be firewall or routing issues. What's the network topology? Are the server and the properly working client on the same side of a firewall or NAT router, with the other non-working clients on the other side? Are the UDP replies from the non-working clients making it onto the wire? Are they arriving at your server, but not being received properly by the server software? (The last few questions could be answered by using a tool like Wireshark to see the network traffic leaving the clients and arriving at the server.)