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// Directory & authentication

Port 129: Password Generator Protocol

Port 129 is assigned by IANA to pwdgen (Password Generator Protocol).

129

How pwdgen works

Directory & authentication
userdirectorypwdgenresponse userdirectorypwdgenresponse

The client proves who it is on port 129 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
01 Security

Is port 129 dangerous?

We have no specific security note for port 129. 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 129

ServicePortTransportDescriptionReferenceUpdated
pwdgen 129 TCP, UDP Password Generator Protocol - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 129, and is it reachable?

Linux

sudo ss -ltnup 'sport = :129'      # process listening on 129
sudo lsof -nP -i :129

macOS

sudo lsof -nP -i :129

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 129 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 129
netstat -ano | findstr :129

From another machine

nmap -p 129 -sV <host>
sudo nmap -sU -p 129 <host>
nc -zv <host> 129

Block it in the firewall

sudo ufw deny 129/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 129" -Direction Inbound -LocalPort 129 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 129 used for?

Port 129 is assigned by IANA to pwdgen (Password Generator Protocol).

Is port 129 TCP or UDP?

Port 129 is registered for TCP and UDP.

Is it safe to open port 129?

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 129 is open?

On Linux run "ss -ltnup 'sport = :129'", on macOS "lsof -nP -i :129", and on Windows "netstat -ano | findstr :129" to see the local process. From another machine, "nmap -p 129 <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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