This value gives the operating-system process ID of the application listening on a particular TCP port, or zero if it cannot be determined, analogous to tcpConnectionProcess but for listening sockets rather than established connections. A system administrator uses this to identify exactly which service is bound to an open port, useful when auditing which processes are exposing network services. For example, tcpListenerProcess showing 1044 for the entry listening on port 443 lets an admin confirm process 1044 is the expected web server and not an unauthorized program.