Reserving a Port for Smack’s Local Bytestream Proxy
Choose a local SOCKS5 listener port when a Smack client shares a development machine with an XMPP proxy service.
When a Smack client and an XMPP server run on the same development machine, their bytestream services need deliberate local port ownership. An “Address already in use” failure occurs while opening the local listener, before a remote file-transfer attempt.
Smack’s documented default local SOCKS5 port is 7777. Check which process already owns the intended address and port. If that is a server-side proxy still needed by other clients, reserve another port for the client instead of disabling the server service.
The documented Socks5Proxy API has setLocalSocks5ProxyPort(int). A negative value requests a search beginning with its absolute value and continuing upward. Read the actual listening port when that selection is allowed, and configure it before starting the listener.
The port the client advertises must remain reachable by the participant expected to connect. Choosing an unused port fixes ownership; it does not publish a route through NAT or a firewall.