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// Other services

Port 19020: J-Link TCP/IP Protocol

Port 19020 is assigned by IANA to j-link (J-Link TCP/IP Protocol).

19020

How j-link works

Other services
client:19020j-linkresponse client:19020j-linkresponse

The client sends a request to port 19020 and the j-link service answers.

Transport
TCP
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 19020 dangerous?

We have no specific security note for port 19020. 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 19020

ServicePortTransportDescriptionReferenceUpdated
j-link 19020 TCP J-Link TCP/IP Protocol - -
-19020-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 19020, and is it reachable?

Linux

sudo ss -ltnup 'sport = :19020'      # process listening on 19020
sudo lsof -nP -i :19020

macOS

sudo lsof -nP -i :19020

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 19020 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 19020
netstat -ano | findstr :19020

From another machine

nmap -p 19020 -sV <host>
nc -zv <host> 19020

Block it in the firewall

sudo ufw deny 19020/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 19020" -Direction Inbound -LocalPort 19020 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 19020 used for?

Port 19020 is assigned by IANA to j-link (J-Link TCP/IP Protocol).

Is port 19020 TCP or UDP?

Port 19020 is registered for TCP.

Is it safe to open port 19020?

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 19020 is open?

On Linux run "ss -ltnup 'sport = :19020'", on macOS "lsof -nP -i :19020", and on Windows "netstat -ano | findstr :19020" to see the local process. From another machine, "nmap -p 19020 <host>" shows whether it is reachable.

05 Related
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