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// Other services

Port 3138: rtnt-2 data packets

Port 3138 is assigned by IANA to rtnt-2 (rtnt-2 data packets).

3138

How rtnt-2 works

Other services
client:3138rtnt-2response client:3138rtnt-2response

The client sends a request to port 3138 and the rtnt-2 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 3138 dangerous?

We have no specific security note for port 3138. 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 3138

ServicePortTransportDescriptionReferenceUpdated
rtnt-2 3138 TCP, UDP rtnt-2 data packets - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 3138, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3138'      # process listening on 3138
sudo lsof -nP -i :3138

macOS

sudo lsof -nP -i :3138

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3138 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3138
netstat -ano | findstr :3138

From another machine

nmap -p 3138 -sV <host>
sudo nmap -sU -p 3138 <host>
nc -zv <host> 3138

Block it in the firewall

sudo ufw deny 3138/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3138" -Direction Inbound -LocalPort 3138 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3138 used for?

Port 3138 is assigned by IANA to rtnt-2 (rtnt-2 data packets).

Is port 3138 TCP or UDP?

Port 3138 is registered for TCP and UDP.

Is it safe to open port 3138?

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 3138 is open?

On Linux run "ss -ltnup 'sport = :3138'", on macOS "lsof -nP -i :3138", and on Windows "netstat -ano | findstr :3138" to see the local process. From another machine, "nmap -p 3138 <host>" shows whether it is reachable.

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