Port 6697 IRC over TLS · TCP

What runs on port 6697

IRC over TLS, the de facto standard port. Libera.Chat, OFTC and nearly all networks offer it and encourage it over 6667.

Software that uses it: InspIRCd, UnrealIRCd, ergo · most IRC networks

Should port 6697 be open?

Designed to face the internet. This port exists to be reachable from anywhere, so the usual question is not whether to open it but how the service behind it is configured and patched.

• Check the server certificate on first connect; clients like WeeChat verify it by default.

Check port 6697

# on the host: is anything listening, and which process?
ss -ltnp 'sport = :6697'
sudo lsof -i :6697

# from another machine: is it reachable?
nc -zv host 6697
nmap -p 6697 host
curl -v telnet://host:6697      # raw TCP connect test, Ctrl-C to leave

A port that answers from the internet when it should not is the finding; nmap from a machine outside your network (or a VPS) is the honest test, because scans from inside the LAN pass the firewall you are trying to verify.

Allow or block port 6697

# ufw (Ubuntu/Debian)
sudo ufw allow from 10.0.0.0/8 to any port 6697 proto tcp
sudo ufw deny 6697/tcp

# nftables
nft add rule inet filter input ip saddr 10.0.0.0/8 tcp dport 6697 accept
nft add rule inet filter input tcp dport 6697 drop

# iptables (legacy)
iptables -A INPUT -p tcp --dport 6697 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 6697 -j DROP

# firewalld
sudo firewall-cmd --permanent --add-rich-rule='rule family=ipv4 source address=10.0.0.0/8 port port=6697 protocol=tcp accept'

Replace 10.0.0.0/8 with the networks that need access. Allowing by source address is the rule that matters; "allow 6697" with no source is just "open".

Related ports

• 6667 IRC — Plaintext; most networks
• 194 IRC

Part of the port number reference. Ports are 16-bit numbers; see also the subnet calculator and the packet decoder, which shows ports inside TCP and UDP headers.

Questions