Port 1701: L2TP
Port 1701 is L2TP, the Layer 2 Tunneling Protocol used to create VPN tunnels. L2TP has no encryption of its own, so it is almost always paired with IPsec, which negotiates over ports 500 and 4500.
UDPRemote accessUnencrypted by defaultIANA assigned
| Port number | 1701 |
|---|---|
| Service | Layer 2 Tunneling Protocol |
| Protocol | UDP |
| Category | Remote access |
| Default encryption | No |
Security note. Port 1701 is not encrypted by default. Restrict it to trusted networks, or use an encrypted alternative where one exists, to avoid exposing credentials and data in transit.
Frequently asked questions
What is port 1701 used for?
Port 1701 is L2TP, the Layer 2 Tunneling Protocol used to create VPN tunnels. L2TP has no encryption of its own, so it is almost always paired with IPsec, which negotiates over ports 500 and 4500.
Is port 1701 TCP or UDP?
Port 1701 (L2TP) uses UDP.
Is port 1701 secure?
Port 1701 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 1701 on my firewall?
Only if you specifically need L2TP. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.