IRC
What is Port 6667?
Port 6667 is the most commonly used port for IRC (Internet Relay Chat) connections, serving as the de facto default for unencrypted IRC client-to-server communication. While IANA officially assigned port 194 for IRC, port 6667 became the standard because it doesn't require root privileges to bind on Unix systems. Virtually every IRC network — Libera.Chat, OFTC, EFnet, Undernet, QuakeNet — accepts connections on port 6667. IRC clients like HexChat, WeeChat, irssi, and mIRC default to port 6667 when connecting to IRC servers. Despite the shift to modern platforms, IRC remains culturally important in the open-source community, with many major projects still coordinating through IRC channels.
Common Uses
- Standard IRC client connections
- Open-source project developer communication
- IRC bot deployment and automation
- Real-time community and support channels
Technical Details
Copy-paste commands to check port 6667 (IRC) from your terminal
Test connectivity
nc -zv example.com 6667
curl -v --max-time 5 http://example.com:6667/
telnet example.com 6667
nmap -p 6667 -sV example.com
(echo > /dev/tcp/example.com/6667) 2>/dev/null && echo "open" || echo "closed"
Open port in firewall
sudo ufw allow 6667/tcp
sudo iptables -A INPUT -p tcp --dport 6667 -j ACCEPT
sudo firewall-cmd --permanent --add-port=6667/tcp && sudo firewall-cmd --reload
Security Considerations
Port 6667 is unencrypted — all messages, including authentication, are sent in plaintext. Always use TLS-encrypted IRC on port 6697 when available. IRC is commonly used as a command-and-control channel for botnets. Security teams should monitor for unauthorized IRC traffic. Implement SASL authentication and register nicknames for identity verification.
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