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// Other services

Port 2691: ITInternet ISM Server

Port 2691 is assigned by IANA to itinternet (ITInternet ISM Server).

2691

How itinternet works

Other services
client:2691itinternetresponse client:2691itinternetresponse

The client sends a request to port 2691 and the itinternet 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 2691 dangerous?

We have no specific security note for port 2691. 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 2691

ServicePortTransportDescriptionReferenceUpdated
itinternet 2691 TCP, UDP ITInternet ISM Server - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2691, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2691'      # process listening on 2691
sudo lsof -nP -i :2691

macOS

sudo lsof -nP -i :2691

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2691 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2691
netstat -ano | findstr :2691

From another machine

nmap -p 2691 -sV <host>
sudo nmap -sU -p 2691 <host>
nc -zv <host> 2691

Block it in the firewall

sudo ufw deny 2691/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2691" -Direction Inbound -LocalPort 2691 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2691 used for?

Port 2691 is assigned by IANA to itinternet (ITInternet ISM Server).

Is port 2691 TCP or UDP?

Port 2691 is registered for TCP and UDP.

Is it safe to open port 2691?

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 2691 is open?

On Linux run "ss -ltnup 'sport = :2691'", on macOS "lsof -nP -i :2691", and on Windows "netstat -ano | findstr :2691" to see the local process. From another machine, "nmap -p 2691 <host>" shows whether it is reachable.

05 Related
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