CyberHunter
Local dataset, no network
// Other services

Port 3871: Avocent DS Authorization

Port 3871 is assigned by IANA to avocent-adsap (Avocent DS Authorization).

3871

How avocent-adsap works

Other services
client:3871avocent-adsapresponse client:3871avocent-adsapresponse

The client sends a request to port 3871 and the avocent-adsap 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 3871 dangerous?

We have no specific security note for port 3871. 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 3871

ServicePortTransportDescriptionReferenceUpdated
avocent-adsap 3871 TCP, UDP Avocent DS Authorization - 2003-08

// source: IANA service name and port number registry

03 Check it

Which program uses port 3871, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3871'      # process listening on 3871
sudo lsof -nP -i :3871

macOS

sudo lsof -nP -i :3871

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3871 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3871
netstat -ano | findstr :3871

From another machine

nmap -p 3871 -sV <host>
sudo nmap -sU -p 3871 <host>
nc -zv <host> 3871

Block it in the firewall

sudo ufw deny 3871/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3871" -Direction Inbound -LocalPort 3871 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3871 used for?

Port 3871 is assigned by IANA to avocent-adsap (Avocent DS Authorization).

Is port 3871 TCP or UDP?

Port 3871 is registered for TCP and UDP.

Is it safe to open port 3871?

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 3871 is open?

On Linux run "ss -ltnup 'sport = :3871'", on macOS "lsof -nP -i :3871", and on Windows "netstat -ano | findstr :3871" to see the local process. From another machine, "nmap -p 3871 <host>" shows whether it is reachable.

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