TCP port 5001 is a well-known port used for the Extensible Messaging and Presence Protocol (XMPP), a communications protocol for instant messaging, presence information, and file transfer.
It is used by various XMPP servers, including Google Talk, Facebook Messenger, and WhatsApp. TCP port 5001 was originally assigned to Jabber, the predecessor of XMPP, and has been in use since the protocol’s inception in 1999.