IRC (alternate)
What is Port 6666?
Port 6666 is part of the IRC port range 6660-6669 and is also historically associated with various other services and malware. In the IRC context, it functions as one of the standard client connection ports. However, port 6666 has additional associations — it was used by the Doom game for multiplayer, some Unix services use it, and unfortunately, several trojans and backdoors have historically used port 6666. The port number's distinctive pattern makes it memorable but also suspicious in security contexts. When detected in network traffic, it's important to verify whether the traffic is legitimate IRC, an authorized application, or potentially malicious.
Common Uses
- IRC server connections
- Application development servers
- Gaming server connections
- Custom application endpoints
Technical Details
Copy-paste commands to check port 6666 (IRC (alternate)) from your terminal
Test connectivity
nc -zv example.com 6666
curl -v --max-time 5 http://example.com:6666/
telnet example.com 6666
nmap -p 6666 -sV example.com
(echo > /dev/tcp/example.com/6666) 2>/dev/null && echo "open" || echo "closed"
Open port in firewall
sudo ufw allow 6666/tcp
sudo iptables -A INPUT -p tcp --dport 6666 -j ACCEPT
sudo firewall-cmd --permanent --add-port=6666/tcp && sudo firewall-cmd --reload
Security Considerations
Port 6666 is flagged by many intrusion detection systems due to historical malware associations. Verify any traffic on this port. Use port 6697 for encrypted IRC. Document any legitimate use of this port in your security policy.
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