- Patch VPN gateways quickly: they are a top initial access target.
- Use certificates or MFA rather than shared secrets.
- Investigate unexpected tunnels and proxies: they are also attacker tools.
Port 3653: Tunnel Setup Protocol
Port 3653 is assigned by IANA to tsp (Tunnel Setup Protocol).
3653
How tsp works
VPN, tunnels & proxiesTraffic is wrapped in a tunnel between the two ends, so the network in between only sees the tunnel.
- Transport
- TCP · UDP
- 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
- VPN, tunnels & proxies
Is port 3653 dangerous?
We have no specific security note for port 3653. Its risk depends on the program actually listening on it. General advice for vpn, tunnels & proxies services:
IANA registry entries for port 3653
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| tsp | 3653 | TCP, UDP | Tunnel Setup Protocol | RFC 5572 | 2003-01 |
// source: IANA service name and port number registry
Which program uses port 3653, and is it reachable?
Linux
sudo ss -ltnup 'sport = :3653' # process listening on 3653
sudo lsof -nP -i :3653macOS
sudo lsof -nP -i :3653
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3653 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 3653 netstat -ano | findstr :3653
From another machine
nmap -p 3653 -sV <host> sudo nmap -sU -p 3653 <host> nc -zv <host> 3653
Block it in the firewall
sudo ufw deny 3653/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 3653" -Direction Inbound -LocalPort 3653 -Protocol TCP -Action Block # Windows
What is port 3653 used for?
Port 3653 is assigned by IANA to tsp (Tunnel Setup Protocol).
Is port 3653 TCP or UDP?
Port 3653 is registered for TCP and UDP.
Is it safe to open port 3653?
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. Patch VPN gateways quickly: they are a top initial access target.
How do I check if port 3653 is open?
On Linux run "ss -ltnup 'sport = :3653'", on macOS "lsof -nP -i :3653", and on Windows "netstat -ano | findstr :3653" to see the local process. From another machine, "nmap -p 3653 <host>" shows whether it is reachable.