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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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Allow traffic only through tun0 via wlan0, ssh, and localhost in and out (feddit.nl)

submitted 1 month ago* (last edited 1 month ago) by [email protected] to c/[email protected]

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Hi all, I'm trying to have my rpi5 running raspberry OS communicate with the Internet only through the tun0 interface (vpn). For this I wanted to create a ufw ruleset. Unfortunately, I've hit a roadblock and I can't figure out where I'm going wrong.

Can you help me discover why this ruleset doesn't allow Internet communication over tun0? When I disable ufw I can access the Internet.

The VPN connection is already established, so it should keep working, right?

I hope you can help me out!

This is the script with the ruleset: sudo ufw reset

Set default policies

sudo ufw default deny incoming

sudo ufw default deny outgoing

Allow SSH access

sudo ufw allow ssh

Allow local network traffic

sudo ufw allow from 192.168.0.0/16

sudo ufw allow out to 192.168.0.0/16

Allow traffic through VPN tunnel

sudo ufw allow in on tun0

sudo ufw allow out on tun0

Add routing between interfaces (I read its necessary, not sure why?)

sudo ufw route allow in on tun0 out on wlan0

sudo ufw route allow in on wlan0 out on tun0

sudo ufw enable

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[–] [email protected] 5 points 1 month ago* (last edited 1 month ago) (8 children)

ufw is a firewall. Routing controls traffic flow. You want to set the default route of that machine to only use the tun0 interface. Random link explains

As a secondary step you can set your firewall to block any traffic trying to exit an interface I suppose, but it really shouldn't be necessary.

For your other services on the local network for your subnet, just add a secondary route only for your subnet that uses your router as a gateway.

[–] [email protected] 1 points 1 month ago (7 children)

That makes sense, but it's possible that the VPN connection drops for a second, and then it can't re-establish it, right? How would I deal with that?

[–] [email protected] 1 points 1 month ago

Remove default route using physical interface

Add route only to the IP of the VPN server

Bring up VPN

Add default route to traverse the tunnel

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