Port / TCP
119NNTP
NNTP transfers Usenet news articles between servers and to reading clients.
If it is internet-facing: Port 119 is routine where it is expected. Its risk lives in the service configuration behind it, not the port itself.
Exposure
Behind a gateway
Transport
Encryption optional
Risk if public
Low
Exposure verdict
Port 119 should sit behind a reverse proxy, VPN, or source allow-list rather than being forwarded at the perimeter. Publishing it directly puts an administrative or internal interface on the open internet.
Encryption is available but negotiated or configured rather than guaranteed. A client that does not insist on it will silently fall back to plaintext.
Assigned by IANA through a review process. On Unix systems a process needs root or the CAP_NET_BIND_SERVICE capability to bind here, which is why containers so often remap these to a higher port.
Grouped with the other messaging & media ports so a rule written for one can be checked against its neighbours.
What actually goes wrong
1 note- Authentication is plaintext unless the session is upgraded; NNTPS on 563 starts encrypted.
Recommended firewall rule
Allow only from 10.0.0.0/8, drop the rest
Swap in the CIDR your administrators or application tier actually come from — the point is that the default answer is no.
ufw
sudo ufw allow from 10.0.0.0/8 to any port 119 proto tcpiptables
sudo iptables -A INPUT -p tcp -s 10.0.0.0/8 --dport 119 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 119 -j DROPIf you do need it open to everyone
sudo ufw allow 119/tcpWrite down why. An unexplained allow rule outlives the person who added it, and the next reviewer has no way to tell a deliberate exception from an accident.
Check what is really there
Listening locally
sudo ss -tlpn 'sport = :119'The bind address is the answer that matters: 127.0.0.1 is local-only, 0.0.0.0 and :: mean every interface.
Listening (macOS)
sudo lsof -nP -iTCP:119 -sTCP:LISTENmacOS ships lsof rather than ss; this names the owning process and user.
From outside
nmap -sV -Pn -p 119 <host>A version probe confirms whether NNTP is actually what answers, rather than trusting the number. Only scan hosts you are authorised to test.
Reachability
nc -vz <host> 119The quick yes/no when you only need to know whether a path exists through the firewall.