- Keep directory and authentication services on internal networks.
- Require signing or TLS and disable anonymous queries.
- Monitor authentication failures for spraying and brute force.
Port 49: Login Host Protocol (TACACS)
Port 49 is assigned by IANA to tacacs (Login Host Protocol (TACACS)).
49
How tacacs works
Directory & authenticationThe client proves who it is on port 49 and gets an answer (or a ticket) it can use with other services.
- Transport
- TCP · UDP
- Exposure risk
- not rated depends on the program listening
- Encryption
- Unknownnot stated by the registry
- IANA status
- Assigned1 registered service
- Range
- Well-known (0-1023)
- Category
- Directory & authentication
Is port 49 dangerous?
We have no specific security note for port 49. Its risk depends on the program actually listening on it. General advice for directory & authentication services:
IANA registry entries for port 49
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| tacacs | 49 | TCP, UDP | Login Host Protocol (TACACS) | - | - |
// source: IANA service name and port number registry
Which program uses port 49, and is it reachable?
Linux
sudo ss -ltnup 'sport = :49' # process listening on 49
sudo lsof -nP -i :49macOS
sudo lsof -nP -i :49
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 49 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 49 netstat -ano | findstr :49
From another machine
nmap -p 49 -sV <host> sudo nmap -sU -p 49 <host> nc -zv <host> 49
Block it in the firewall
sudo ufw deny 49/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 49" -Direction Inbound -LocalPort 49 -Protocol TCP -Action Block # Windows
What is port 49 used for?
Port 49 is assigned by IANA to tacacs (Login Host Protocol (TACACS)).
Is port 49 TCP or UDP?
Port 49 is registered for TCP and UDP.
Is it safe to open port 49?
It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Keep directory and authentication services on internal networks.
How do I check if port 49 is open?
On Linux run "ss -ltnup 'sport = :49'", on macOS "lsof -nP -i :49", and on Windows "netstat -ano | findstr :49" to see the local process. From another machine, "nmap -p 49 <host>" shows whether it is reachable.