- 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 749: kerberos administration
Port 749 is assigned by IANA to kerberos-adm (kerberos administration).
749
How kerberos-adm works
Directory & authenticationThe client proves who it is on port 749 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 749 dangerous?
We have no specific security note for port 749. Its risk depends on the program actually listening on it. General advice for directory & authentication services:
IANA registry entries for port 749
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| kerberos-adm | 749 | TCP, UDP | kerberos administration | - | - |
// source: IANA service name and port number registry
Which program uses port 749, and is it reachable?
Linux
sudo ss -ltnup 'sport = :749' # process listening on 749
sudo lsof -nP -i :749macOS
sudo lsof -nP -i :749
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 749 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 749 netstat -ano | findstr :749
From another machine
nmap -p 749 -sV <host> sudo nmap -sU -p 749 <host> nc -zv <host> 749
Block it in the firewall
sudo ufw deny 749/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 749" -Direction Inbound -LocalPort 749 -Protocol TCP -Action Block # Windows
What is port 749 used for?
Port 749 is assigned by IANA to kerberos-adm (kerberos administration).
Is port 749 TCP or UDP?
Port 749 is registered for TCP and UDP.
Is it safe to open port 749?
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 749 is open?
On Linux run "ss -ltnup 'sport = :749'", on macOS "lsof -nP -i :749", and on Windows "netstat -ano | findstr :749" to see the local process. From another machine, "nmap -p 749 <host>" shows whether it is reachable.
Other directory & authentication ports
:389 LDAP tcp · udp · high risk :636 LDAPS tcp · udp · moderate risk :88 Kerberos tcp · udp · high risk :3268 Global Catalog (LDAP) tcp · udp · high risk :1812 RADIUS udp · tcp · moderate risk :31 MSG Authentication tcp · udp :49 Login Host Protocol (TACACS) tcp · udp :56 XNS Authentication tcp · udp