Port 194 (TCP) — IRC: what it is, how to check

Port 194 IRC · TCP

IRC: plaintext internet relay chat on 194 by convention, though nearly every network actually listens on 6667 (plain) and 6697 (TLS).

Port	194
Transport	TCP
Service	IRC
Category	Chat and messaging
Range	well-known (0–1023, needs root to bind on Unix)
Encrypted	No, plaintext
Exposure	Designed to face the internet

What runs on port 194

IRC: plaintext internet relay chat on 194 by convention, though nearly every network actually listens on 6667 (plain) and 6697 (TLS). Still the backbone of many open-source projects' real-time chat, often bridged to Matrix.

Software that uses it: ircd (InspIRCd, UnrealIRCd, ergo) · irssi/WeeChat (clients) · The Lounge

Should port 194 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.

Use 6697 with TLS; many networks refuse plaintext for new connections.

Check port 194

# on the host: is anything listening, and which process?
ss -ltnp 'sport = :194'
sudo lsof -i :194

# from another machine: is it reachable?
nc -zv host 194
nmap -p 194 host
curl -v telnet://host:194      # 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 194

# ufw (Ubuntu/Debian)
sudo ufw allow from 10.0.0.0/8 to any port 194 proto tcp
sudo ufw deny 194/tcp

# nftables
nft add rule inet filter input ip saddr 10.0.0.0/8 tcp dport 194 accept
nft add rule inet filter input tcp dport 194 drop

# iptables (legacy)
iptables -A INPUT -p tcp --dport 194 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 194 -j DROP

# firewalld
sudo firewall-cmd --permanent --add-rich-rule='rule family=ipv4 source address=10.0.0.0/8 port port=194 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 194" with no source is just "open".

Related ports

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

Is port 194 TCP or UDP?

TCP. IRC is a connection-oriented protocol; there is no UDP service on 194 by default (a scanner reporting UDP 194 open is usually seeing a filtered port).

Is port 194 encrypted?

No, plaintext. Anything sent over it can be read by whoever is on the path, so it belongs on a trusted network or inside a VPN or SSH tunnel.

How do I check whether port 194 is open?

On the server, ss -ltnp (or -lunp for UDP) shows whether something listens on 194 and which process. From another machine, nc -zv host 194 or nmap -p 194 host tests reachability. "Open" in a scan means something answered; a firewall usually makes the port filtered (no answer) rather than closed (RST).

Can IRC run on a different port?

Yes; the number is a convention, not a requirement. Changing it reduces log noise from scanners but does not add security, and every client, firewall rule and monitoring check then needs the new number. Keep the default unless you have a concrete reason.