VMS Help TCPIP Services, Tracing  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The TCPTRACE utility lets you trace packet flow between the local
    host and remote hosts. You can either monitor all packet flow
    or use the various qualifiers to monitor only those packets of
    interest.

1 - Starting

    To start the TCPTRACE utility use the TCPTRACE command:

    $  TCPTRACE HOST1 /FULL /PACKETS=30

2 - Stopping

    To stop the TCPTRACE utility use CTRL/C.