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Port 3653 (tsp)

IANA assigns port 3653 to tsp: Tunnel Setup Protocol.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
tsp TCP Tunnel Setup Protocol Marc Blanchet RFC 5572
tsp UDP Tunnel Setup Protocol Marc Blanchet RFC 5572

Registry dates for this port: registered 2003-01.

Check what is listening on port 3653

Linux: is anything listening on TCP 3653?
sudo ss -tlnp 'sport = :3653'
Linux: UDP 3653
sudo ss -ulnp 'sport = :3653'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3653
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3653 '
Windows (Command Prompt)
netstat -ano | findstr :3653
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3653 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3653
From Windows
Test-NetConnection HOST -Port 3653
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3653

Block port 3653 in the firewall

ufw
sudo ufw deny 3653/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3653 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3653 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3653' -Direction Inbound -Protocol TCP -LocalPort 3653 -Action Block
ufw
sudo ufw deny 3653/udp
iptables
sudo iptables -A INPUT -p udp --dport 3653 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3653 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3653' -Direction Inbound -Protocol UDP -LocalPort 3653 -Action Block

Related ports

3651xrpc-registry3652vxcrnbuport3654vaprtm3655abatemgr

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