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// Other services

Port 3851: SpectraTalk Port

Port 3851 is assigned by IANA to spectraport (SpectraTalk Port).

3851

How spectraport works

Other services
client:3851spectraportresponse client:3851spectraportresponse

The client sends a request to port 3851 and the spectraport 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 3851 dangerous?

We have no specific security note for port 3851. 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 3851

ServicePortTransportDescriptionReferenceUpdated
spectraport 3851 TCP, UDP SpectraTalk Port - 2003-08

// source: IANA service name and port number registry

03 Check it

Which program uses port 3851, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3851'      # process listening on 3851
sudo lsof -nP -i :3851

macOS

sudo lsof -nP -i :3851

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3851 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3851
netstat -ano | findstr :3851

From another machine

nmap -p 3851 -sV <host>
sudo nmap -sU -p 3851 <host>
nc -zv <host> 3851

Block it in the firewall

sudo ufw deny 3851/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3851" -Direction Inbound -LocalPort 3851 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3851 used for?

Port 3851 is assigned by IANA to spectraport (SpectraTalk Port).

Is port 3851 TCP or UDP?

Port 3851 is registered for TCP and UDP.

Is it safe to open port 3851?

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 3851 is open?

On Linux run "ss -ltnup 'sport = :3851'", on macOS "lsof -nP -i :3851", and on Windows "netstat -ano | findstr :3851" to see the local process. From another machine, "nmap -p 3851 <host>" shows whether it is reachable.

05 Related
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