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// Directory & authentication

Port 3269: Microsoft Global Catalog with LDAP/SSL

Port 3269 is assigned by IANA to msft-gc-ssl (Microsoft Global Catalog with LDAP/SSL).

3269

How msft-gc-ssl works

Directory & authentication
userdirectory#%&@!x9response? userdirectory#%&@!x9response?

The client proves who it is on port 3269 and gets an answer (or a ticket) it can use with other services. Everything is encrypted: someone on the path only sees unreadable bytes.

Transport
TCP · UDP
Exposure risk
not rated depends on the program listening
Encryption
EncryptedTLS or built-in crypto
IANA status
Assigned1 registered service
Range
Registered (1024-49151)
Category
Directory & authentication
01 Security

Is port 3269 dangerous?

We have no specific security note for port 3269. Its risk depends on the program actually listening on it. General advice for directory & authentication services:

  • Keep directory and authentication services on internal networks.
  • Require signing or TLS and disable anonymous queries.
  • Monitor authentication failures for spraying and brute force.
02 Registry

IANA registry entries for port 3269

ServicePortTransportDescriptionReferenceUpdated
msft-gc-ssl 3269 TCP, UDP Microsoft Global Catalog with LDAP/SSL - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 3269, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3269'      # process listening on 3269
sudo lsof -nP -i :3269

macOS

sudo lsof -nP -i :3269

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3269 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3269
netstat -ano | findstr :3269

From another machine

nmap -p 3269 -sV <host>
sudo nmap -sU -p 3269 <host>
nc -zv <host> 3269

Block it in the firewall

sudo ufw deny 3269/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3269" -Direction Inbound -LocalPort 3269 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3269 used for?

Port 3269 is assigned by IANA to msft-gc-ssl (Microsoft Global Catalog with LDAP/SSL).

Is port 3269 TCP or UDP?

Port 3269 is registered for TCP and UDP.

Is it safe to open port 3269?

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 3269 is open?

On Linux run "ss -ltnup 'sport = :3269'", on macOS "lsof -nP -i :3269", and on Windows "netstat -ano | findstr :3269" to see the local process. From another machine, "nmap -p 3269 <host>" shows whether it is reachable.

05 Related
: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

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