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Port 19541 (jcp)

IANA assigns port 19541 to jcp: JCP Client.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
jcp TCP JCP Client Yuji Sasaki -
jcp UDP JCP Client Yuji Sasaki -

Check what is listening on port 19541

Linux: is anything listening on TCP 19541?
sudo ss -tlnp 'sport = :19541'
Linux: UDP 19541
sudo ss -ulnp 'sport = :19541'
Linux / macOS: which process owns the port
sudo lsof -nP -i :19541
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':19541 '
Windows (Command Prompt)
netstat -ano | findstr :19541
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 19541 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 19541
From Windows
Test-NetConnection HOST -Port 19541
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 19541

Block port 19541 in the firewall

ufw
sudo ufw deny 19541/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 19541 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 19541 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 19541' -Direction Inbound -Protocol TCP -LocalPort 19541 -Action Block
ufw
sudo ufw deny 19541/udp
iptables
sudo iptables -A INPUT -p udp --dport 19541 -j DROP
nftables
sudo nft add rule inet filter input udp dport 19541 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 19541' -Direction Inbound -Protocol UDP -LocalPort 19541 -Action Block

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