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// Other services

Port 681: entrust-aams

Port 681 is assigned by IANA to entrust-aams (entrust-aams).

681

How entrust-aams works

Other services
client:681entrust-aamsresponse client:681entrust-aamsresponse

The client sends a request to port 681 and the entrust-aams 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
Well-known (0-1023)
Category
Other services
01 Security

Is port 681 dangerous?

We have no specific security note for port 681. 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 681

ServicePortTransportDescriptionReferenceUpdated
entrust-aams 681 TCP, UDP entrust-aams - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 681, and is it reachable?

Linux

sudo ss -ltnup 'sport = :681'      # process listening on 681
sudo lsof -nP -i :681

macOS

sudo lsof -nP -i :681

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 681 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 681
netstat -ano | findstr :681

From another machine

nmap -p 681 -sV <host>
sudo nmap -sU -p 681 <host>
nc -zv <host> 681

Block it in the firewall

sudo ufw deny 681/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 681" -Direction Inbound -LocalPort 681 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 681 used for?

Port 681 is assigned by IANA to entrust-aams (entrust-aams).

Is port 681 TCP or UDP?

Port 681 is registered for TCP and UDP.

Is it safe to open port 681?

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 681 is open?

On Linux run "ss -ltnup 'sport = :681'", on macOS "lsof -nP -i :681", and on Windows "netstat -ano | findstr :681" to see the local process. From another machine, "nmap -p 681 <host>" shows whether it is reachable.

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