Port 3737 (xpanel)

IANA assigns port 3737 to xpanel: XPanel Daemon.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference

xpanel TCP XPanel Daemon Lilian Rudenco -

Registry dates for this port: registered 2009-03-04.

Linux: is anything listening on TCP 3737?

sudo ss -tlnp 'sport = :3737'

Linux / macOS: which process owns the port

sudo lsof -nP -i :3737

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':3737 '

Windows (Command Prompt)

netstat -ano | findstr :3737

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3737 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 3737

From Windows

Test-NetConnection HOST -Port 3737

ufw

sudo ufw deny 3737/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 3737 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 3737 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 3737' -Direction Inbound -Protocol TCP -LocalPort 3737 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.