A centralized messaging solution for very restrictive networks over ICMP written in Go. If your client device can perform a simple ping google.com, it can use this.
The ICMP RFC allows for sending a payload as part of the message. The protocol also has built-in acknowledgments without the need for transport level acknowledgments (An Echo Request is replied to with An Echo Reply containing the same ID). The client sends their messages as ICMP Echo Requests to the centralized Server, which responds with an Echo Reply, acknowledging the message was successfully delivered. For receiving messages, the client sends an Echo Request containing a special payload, and the server responds with an Echo Reply containing the next available message addressed to the user, or with a message indicating there are no more messages left. This approach means the client can receive messages behind a NAT
One of the major advantages of the Client Server approach is sending messages to clients behind NAT. Also, since ICMP is a port-less protocol, port forwarding is not an option .A simpler, safer P2P design can be implemented if both peers use IPv6.
The program can run in either client or server mode. It needs root permissions in both cases in order to sniff ICMP packets.
To run the program in server mode.
./icmp-chat --server
There is no limit to clients using the same server.
./icmp-chat --client --server-ip=SERVER_IP --username=USERNAME
Once in client mode, you can:
- Send a new message, using
username:message - Request incoming messages, using
receive:username