Enable HTTPS Filtering: Chain ProxHTTPSProxyMII to Privoxy (OS X Tutorial)

[Faxopita]

Allow Privoxy to Block All Requests if VPN Turned Off!

Some VPN apps offer the option to block Internet access if, for example, they happen to be disabled accidentally. I don't have this option, so I decided to create a tiny script to do that job (to some extent) with the help of Privoxy. The script automatically blocks all HTTP/HTTPS requests if your VPN is down. To do so, it simply uncomments these lines if TUN device is not returned in ifconfig output:

Code:

# { +block{VPN is not running. Turn it on first!} }
#  /

Be warned that the script will not deal with layers other than HTTP/HTTPS. So, you might still be able to use, for example, SMTP or FTP if your VPN is down. Any exception rule under `{ -block }` put after the above enforced block action will still allow for Internet access even though your VPN is down; useful to let you at least connect to your VPN, by the way…

If you are interested, then this post is for you, but first: retrieve the attached archive to this post and back up immediately your `user.action` file!

Design choice: the script does its own little job only if the hidden file `.AllVPN` is present in your Home directory. It's a kind of a switch. It's a choice I made, but you can certainly modify the script so it doesn't take account of this switch! So, for now, create it with your favourite Terminal:

Code:

cd `echo $HOME`
touch .AllVPN

Amend your own `user.action` file.

Add this section at the end of your `user.action` file:

Code:

# { +block{VPN is not running. Turn it on first!} }
#  /

  { -block }
# However, you have to whitelist your VPN provider here…

Also, be warned the script requires you to have write permissions on `user.action` file; in Terminal `cd` to your Privoxy directory, then…

Code:

sudo chmod 664 user.action
sudo chown `echo $USER`:admin user.action

Amend script AllVPN.

1. The script uses GNU sed; I got it with Homebrew. Perhaps you'd like to use the version installed with the base system. If so, you might find the need to tweak the corresponding syntax in the script.
   
   Code:
   

   brew info gnu-sed
brew home gnu-sed
brew install gnu-sed
2. Allocate your own paths to `pri_path` and `sed_path`.
3. Copy AllVPN.sh script to your script folder.
   

Setting up the dæmon.

1. Copy privoxy.vpn.bridge.plist to ~/Library/LaunchAgents; it's the one attached to your Home directory.
2. Edit the above .PLIST file and replace [INSERT_ABSOLUTE_PATH] by the path—in absolute terms—leading to the script `AllVPN.sh`.
3. Service should start automatically at next login, but you can run it now; `cd` first to `~/Library/LaunchAgents`, then…
   • launchctl load privoxy.vpn.bridge.plist
   • To stop the service: launchctl unload privoxy.vpn.bridge.plist
   • To verify the service is loaded: launchctl list | grep "bridge"
     

-–—

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