6667
IRC server standard port — unencrypted
Internet Relay Chat (IRC)
What is port 6667?
Port 6667 is the de facto standard port for IRC servers in practice, even though the officially IANA-assigned port is 194. It is used for real-time group chat with IRC clients such as HexChat, irssi, and WeeChat. Major IRC networks include Libera.Chat, OFTC, and IRCnet. The connection is unencrypted — use port 6697 (SSL/TLS) for a secure connection.
Quick checks
$
nc -zv example.com 6667
$
nmap -p 6667 example.com
$
telnet example.com 6667