Bytes the server prepends to every relayed datagram identifying the
sender's session ID (big-endian uint32). The client strips this prefix
on read and never writes it on send — the server stamps outgoing
datagrams with the connection's own session ID.
Bytes the server prepends to every relayed datagram identifying the sender's session ID (big-endian uint32). The client strips this prefix on read and never writes it on send — the server stamps outgoing datagrams with the connection's own session ID.