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// Other services

Port 3902: NIMsh Auxiliary Port

Port 3902 is assigned by IANA to nimaux (NIMsh Auxiliary Port).

3902

How nimaux works

Other services
client:3902nimauxresponse client:3902nimauxresponse

The client sends a request to port 3902 and the nimaux 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 3902 dangerous?

We have no specific security note for port 3902. 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 3902

ServicePortTransportDescriptionReferenceUpdated
nimaux 3902 TCP, UDP NIMsh Auxiliary Port - 2003-10

// source: IANA service name and port number registry

03 Check it

Which program uses port 3902, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3902'      # process listening on 3902
sudo lsof -nP -i :3902

macOS

sudo lsof -nP -i :3902

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3902 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3902
netstat -ano | findstr :3902

From another machine

nmap -p 3902 -sV <host>
sudo nmap -sU -p 3902 <host>
nc -zv <host> 3902

Block it in the firewall

sudo ufw deny 3902/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3902" -Direction Inbound -LocalPort 3902 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3902 used for?

Port 3902 is assigned by IANA to nimaux (NIMsh Auxiliary Port).

Is port 3902 TCP or UDP?

Port 3902 is registered for TCP and UDP.

Is it safe to open port 3902?

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 3902 is open?

On Linux run "ss -ltnup 'sport = :3902'", on macOS "lsof -nP -i :3902", and on Windows "netstat -ano | findstr :3902" to see the local process. From another machine, "nmap -p 3902 <host>" shows whether it is reachable.

05 Related
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