A server usually remains in the Discovery state while running.

The Discovery Socket is opened, as a nonblocking broadcast socket. It is bound to the server’s address with the Server Discovery Port (default 10600).

A Client that wants to join (the Connecting Client) periodically sends to the server a four-byte Connection Request packet containing an unsigned 32-bit integer, the Client ID.

The Discovery Service listens on the Discovery Socket for a Connection Request from a Connecting Client. When one is received, if the server is set to filter client addresses, the Connecting Client’s address is filtered, and the connection is discarded it does not match the filter.

Otherwise, the server sends the Connecting Client on the Client Discovery Port a 6-byte Service Discovery Response consisting of the Client ID (4 bytes) and the Service Server Port (2 bytes as an unsigned 16-bit integer). The Server Service Port must be different for each Client.

In between periodically sending its Connection Request packets, a Connecting Client listens on the Client Discovery Port for the Service Discovery Response. On receiving this, it destroys its Discovery Socket and starts its Service Connection bound to the Server Service Port.