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Naveen Sunil
Naveen Sunil
Information Technology
06 Jan 2019

How to block VPN connections through Firewall?

VPN uses certain services like PPTP over a network, which means VPN uses certain encrypted channel and it is called protocol tunneling. 

Basic blocking method involves blocking of the ports used by these VPNs which can be identified by a Networks expert and could be blocked on the firewall.

Do you know other ways to block VPN connections through firewall? Do post them below!

Abhishek Rawal
Abhishek Rawal
Electronics and Communication
4mos ago

There are usually two configurations (atleast in good firewalls/DPI)

Content filtering for URL filtering. Application layer rules for applications. Correct term would be services instead of applications.


The really interesting part would be "how is it done".

4mos ago

I think URL filtering doesn't work in all the cases. Tagging @Rahul Jamgade for some inputs. 

Naveen Sunil
Naveen Sunil
Information Technology
4mos ago

Yes URL filtering works just on the Application layer. But using a VPN allows someone to tunnel a connection. VPN either uses an TLS connection on the firewall open ports or it creates a tunnel (uses a different port which usually does not go through the firewall)

But today's VPN also allows one to connect to different country's server to get info which is blocked or restricted.

Working on creating a network level block is the way to restrict VPN connections.

Manimalika Katakam
Manimalika Katakam
Information Technology
3mos ago

why do we block VPN connections?

Willie Ames
Willie Ames
Computer Science
2mos ago

Depending on what type of VPN, it might not require deep packet inspection.

If it’s an IPSec VPN, then not permitting UDP 500 (and potentially: AH & ESP) will prevent connectivity.

Source: Best VPN Services | 80+ Providers Tested and Reviewed in 2019