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// Directory & authentication

Port 1333: Password Policy

Port 1333 is assigned by IANA to passwrd-policy (Password Policy).

1333

How passwrd-policy works

Directory & authentication
userdirectorypasswrd-policyresponse userdirectorypasswrd-policyresponse

The client proves who it is on port 1333 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
Registered (1024-49151)
Category
Directory & authentication
01 Security

Is port 1333 dangerous?

We have no specific security note for port 1333. 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 1333

ServicePortTransportDescriptionReferenceUpdated
passwrd-policy 1333 TCP, UDP Password Policy - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1333, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1333'      # process listening on 1333
sudo lsof -nP -i :1333

macOS

sudo lsof -nP -i :1333

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1333 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1333
netstat -ano | findstr :1333

From another machine

nmap -p 1333 -sV <host>
sudo nmap -sU -p 1333 <host>
nc -zv <host> 1333

Block it in the firewall

sudo ufw deny 1333/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1333" -Direction Inbound -LocalPort 1333 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1333 used for?

Port 1333 is assigned by IANA to passwrd-policy (Password Policy).

Is port 1333 TCP or UDP?

Port 1333 is registered for TCP and UDP.

Is it safe to open port 1333?

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 1333 is open?

On Linux run "ss -ltnup 'sport = :1333'", on macOS "lsof -nP -i :1333", and on Windows "netstat -ano | findstr :1333" to see the local process. From another machine, "nmap -p 1333 <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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