'^.*p$' : it's all about protocols !

FTP

2014-11-30
The FTP protocol
PORT, PASV
2013-08-22 2005-07-20
FTP reply codes

HTTP

2019-08-27 2006-04-04
HTTP status codes
2019-05-27
HTTP/2
2018-03-13
How to check whether HTTP keep-alive is enabled ?
2014-09-18 2013-11-08
HTTP Headers
2014-05-06
HTTP ETag
2014-01-02 2012-04-19
HTTP caching pragma headers
akamai, mem_hit, tcp_hit, tcp_miss, tcp_refresh