How to unbind port

From time to time apache after restart doesn't close used ports and You have to restart server. This we don't want. Solution is pretty simple:

find process IDs

$ lsof -i TCP:80

output:

apache2 16442 www-data    3u  IPv4 1158908      0t0  TCP s0.domain.tld:80 (CLOSE_WAIT)

...

then we kill process(es)

$ kill -9 16442