Banner grabbing

shells_and_payloads activerecon netsecchallenge

Banner grabbing refer to manually probing a service to find information about it in the banner they send. There may not be anything useful. This done automatically by tools such as nmap along other checks, so we usually don't do it ☠️.

You can use telnet for TCP, and netcat for both TCP/UDP.

$ telnet IP 21
[...] FTP server (Version 6.4/OpenBSD/Linux-ftpd-0.17) ready.

$ nc IP 21
[...] FTP server (Version 6.4/OpenBSD/Linux-ftpd-0.17) ready.