Port 19020 (j-link)

IANA assigns port 19020 to j-link: J-Link TCP/IP Protocol.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference

j-link TCP J-Link TCP/IP Protocol SEGGER -

Linux: is anything listening on TCP 19020?

sudo ss -tlnp 'sport = :19020'

Linux / macOS: which process owns the port

sudo lsof -nP -i :19020

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':19020 '

Windows (Command Prompt)

netstat -ano | findstr :19020

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 19020 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 19020

From Windows

Test-NetConnection HOST -Port 19020

ufw

sudo ufw deny 19020/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 19020 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 19020 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 19020' -Direction Inbound -Protocol TCP -LocalPort 19020 -Action Block

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.