License: Public Domain

A simple UDP echo server which can be used for some NAT traversal routines (UDP hole punching). There is although a simple demonstration client.

Building:

Just enter make in the client or server directory.

Tested on Linux only.

Running:

start echoserver [Port] or echoclient [IP] [Port] to start the server or the client.

Protocol:

The client sends a UDP datagram consisting of

condata $SomeKey

to the server.

The server replies each request with

condataReply $SomeKey $IPAddress $Port

The $IPAdress is in regular 4 Byte Notation: 1.2.3.4

The $SomeKey isn't a security feature but can be used to distinguish between different ports during a Hole Punching Procedure.

Example:

Client to Server --> condata 0x12345678 Server to Client <-- condataReply 0x12345678 127.0.0.1 6843

Warranty & Security

Plaintext UDP is not secure at all. There is no warranty for anything.