Port / TCP
49TACACS+
TACACS+ centralises authentication, authorisation, and command accounting for network device administration.
If it is internet-facing: Port 49 is legitimate in the right place, but exposed carelessly it widens the attack surface noticeably.
Exposure
Trusted network only
Transport
Encryption optional
Risk if public
Elevated
Exposure verdict
Port 49 belongs on a trusted internal network. If a perimeter scan finds it answering, treat that as a firewall defect rather than a configuration preference.
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 directory & auth ports so a rule written for one can be checked against its neighbours.
What actually goes wrong
2 notes- The body obfuscation uses a shared secret with MD5 and is not equivalent to modern transport encryption.
- It carries device admin credentials, so reachability should be limited to management networks.
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 49 proto tcpiptables
sudo iptables -A INPUT -p tcp -s 10.0.0.0/8 --dport 49 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 49 -j DROPIf you do need it open to everyone
sudo ufw allow 49/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 = :49'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:49 -sTCP:LISTENmacOS ships lsof rather than ss; this names the owning process and user.
From outside
nmap -sV -Pn -p 49 <host>A version probe confirms whether TACACS+ is actually what answers, rather than trusting the number. Only scan hosts you are authorised to test.
Reachability
nc -vz <host> 49The quick yes/no when you only need to know whether a path exists through the firewall.