- 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 3663: DIRECWAY Tunnel Protocol
Port 3663 is assigned by IANA to dtp (DIRECWAY Tunnel Protocol).
3663
How dtp 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 3663 dangerous?
We have no specific security note for port 3663. Its risk depends on the program actually listening on it. General advice for vpn, tunnels & proxies services:
IANA registry entries for port 3663
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| dtp | 3663 | TCP, UDP | DIRECWAY Tunnel Protocol | - | 2003-01 |
// source: IANA service name and port number registry
Which program uses port 3663, and is it reachable?
Linux
sudo ss -ltnup 'sport = :3663' # process listening on 3663
sudo lsof -nP -i :3663macOS
sudo lsof -nP -i :3663
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3663 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 3663 netstat -ano | findstr :3663
From another machine
nmap -p 3663 -sV <host> sudo nmap -sU -p 3663 <host> nc -zv <host> 3663
Block it in the firewall
sudo ufw deny 3663/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 3663" -Direction Inbound -LocalPort 3663 -Protocol TCP -Action Block # Windows
What is port 3663 used for?
Port 3663 is assigned by IANA to dtp (DIRECWAY Tunnel Protocol).
Is port 3663 TCP or UDP?
Port 3663 is registered for TCP and UDP.
Is it safe to open port 3663?
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 3663 is open?
On Linux run "ss -ltnup 'sport = :3663'", on macOS "lsof -nP -i :3663", and on Windows "netstat -ano | findstr :3663" to see the local process. From another machine, "nmap -p 3663 <host>" shows whether it is reachable.