CyberHunter
Local dataset, no network
// Other services

Port 5729: Openmail User Agent Layer

Port 5729 is assigned by IANA to openmail (Openmail User Agent Layer).

5729

How openmail works

Other services
client:5729openmailresponse client:5729openmailresponse

The client sends a request to port 5729 and the openmail service answers.

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
Other services
01 Security

Is port 5729 dangerous?

We have no specific security note for port 5729. Its risk depends on the program actually listening on it. General advice for other services services:

  • Close the port if nothing on the host needs it.
  • Identify the process that listens on it (commands below) before opening it in a firewall.
  • Expose a service only to the networks that use it.
02 Registry

IANA registry entries for port 5729

ServicePortTransportDescriptionReferenceUpdated
openmail 5729 TCP, UDP Openmail User Agent Layer - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 5729, and is it reachable?

Linux

sudo ss -ltnup 'sport = :5729'      # process listening on 5729
sudo lsof -nP -i :5729

macOS

sudo lsof -nP -i :5729

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 5729 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 5729
netstat -ano | findstr :5729

From another machine

nmap -p 5729 -sV <host>
sudo nmap -sU -p 5729 <host>
nc -zv <host> 5729

Block it in the firewall

sudo ufw deny 5729/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 5729" -Direction Inbound -LocalPort 5729 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 5729 used for?

Port 5729 is assigned by IANA to openmail (Openmail User Agent Layer).

Is port 5729 TCP or UDP?

Port 5729 is registered for TCP and UDP.

Is it safe to open port 5729?

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. Close the port if nothing on the host needs it.

How do I check if port 5729 is open?

On Linux run "ss -ltnup 'sport = :5729'", on macOS "lsof -nP -i :5729", and on Windows "netstat -ano | findstr :5729" to see the local process. From another machine, "nmap -p 5729 <host>" shows whether it is reachable.

05 Related
:4444 Metasploit default / krb524 tcp · udp · high risk :31337 Back Orifice / elite tcp · udp · high risk :1 TCP Port Service Multiplexer tcp · udp :5 Remote Job Entry tcp · udp :9 Discard tcp · udp · sctp · dccp :11 Active Users tcp · udp :17 Quote of the Day tcp · udp :18 Message Send Protocol (historic) tcp · udp

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