CyberHunter
Local dataset, no network
// Other services

Port 2991: WKSTN-MON

Port 2991 is assigned by IANA to wkstn-mon (WKSTN-MON).

2991

How wkstn-mon works

Other services
client:2991wkstn-monresponse client:2991wkstn-monresponse

The client sends a request to port 2991 and the wkstn-mon 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 2991 dangerous?

We have no specific security note for port 2991. 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 2991

ServicePortTransportDescriptionReferenceUpdated
wkstn-mon 2991 TCP, UDP WKSTN-MON - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2991, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2991'      # process listening on 2991
sudo lsof -nP -i :2991

macOS

sudo lsof -nP -i :2991

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2991 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2991
netstat -ano | findstr :2991

From another machine

nmap -p 2991 -sV <host>
sudo nmap -sU -p 2991 <host>
nc -zv <host> 2991

Block it in the firewall

sudo ufw deny 2991/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2991" -Direction Inbound -LocalPort 2991 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2991 used for?

Port 2991 is assigned by IANA to wkstn-mon (WKSTN-MON).

Is port 2991 TCP or UDP?

Port 2991 is registered for TCP and UDP.

Is it safe to open port 2991?

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 2991 is open?

On Linux run "ss -ltnup 'sport = :2991'", on macOS "lsof -nP -i :2991", and on Windows "netstat -ano | findstr :2991" to see the local process. From another machine, "nmap -p 2991 <host>" shows whether it is reachable.

05 Related
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