TCP port monitoring and discovery

pip install portend==3.1.0


tests Code style: Black https://readthedocs.org/projects/portend/badge/?version=latest https://img.shields.io/badge/skeleton-2021-informational

por·tend pôrˈtend/ verb

be a sign or warning that (something, especially something momentous or calamitous) is likely to happen.


Use portend to monitor TCP ports for bound or unbound states.

For example, to wait for a port to be occupied, timing out after 3 seconds:

portend.occupied('www.google.com', 80, timeout=3)

Or to wait for a port to be free, timing out after 5 seconds:

portend.free('::1', 80, timeout=5)

The portend may also be executed directly. If the function succeeds, it returns nothing and exits with a status of 0. If it fails, it prints a message and exits with a status of 1. For example:

python -m portend localhost:31923 free
(exits immediately)

python -m portend -t 1 localhost:31923 occupied
(one second passes)
Port 31923 not bound on localhost.

Portend also exposes a find_available_local_port for identifying a suitable port for binding locally:

port = portend.find_available_local_port()
print(port, "is available for binding")

Portend additionally exposes the lower-level port checking functionality in the Checker class, which currently exposes only one public method, assert_free:

portend.Checker().assert_free('localhost', 31923)

If assert_free is passed a host/port combination that is occupied by a bound listener (i.e. a TCP connection is established to that host/port), assert_free will raise a PortNotFree exception.