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// Other services

Port 1801: Microsoft Message Que

Port 1801 is assigned by IANA to msmq (Microsoft Message Que).

1801

How msmq works

Other services
client:1801msmqresponse client:1801msmqresponse

The client sends a request to port 1801 and the msmq 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 1801 dangerous?

We have no specific security note for port 1801. 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 1801

ServicePortTransportDescriptionReferenceUpdated
msmq 1801 TCP, UDP Microsoft Message Que - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1801, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1801'      # process listening on 1801
sudo lsof -nP -i :1801

macOS

sudo lsof -nP -i :1801

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1801 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1801
netstat -ano | findstr :1801

From another machine

nmap -p 1801 -sV <host>
sudo nmap -sU -p 1801 <host>
nc -zv <host> 1801

Block it in the firewall

sudo ufw deny 1801/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1801" -Direction Inbound -LocalPort 1801 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1801 used for?

Port 1801 is assigned by IANA to msmq (Microsoft Message Que).

Is port 1801 TCP or UDP?

Port 1801 is registered for TCP and UDP.

Is it safe to open port 1801?

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 1801 is open?

On Linux run "ss -ltnup 'sport = :1801'", on macOS "lsof -nP -i :1801", and on Windows "netstat -ano | findstr :1801" to see the local process. From another machine, "nmap -p 1801 <host>" shows whether it is reachable.

05 Related
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