firewall settings to prevent leaks - something is wrong

[j1smith 0]

I know this is a common topic, but for the life of me I can't figure out what is wrong with my setup. So the deal is as usual: I try to set up some firewall rules to prevent leaks. Operating system is Linux (Ubuntu and Mint). I start openvpn from command line:

 

sudo openvpn xxx.ovpn

 

The tunnel seems to get established, at the end I get the "Initialization Sequence Completed" message. Everything works.

 

Then I start my firewall, which has only two rules (and the corresponding two for v6). Note that these are in gufw format.

 

Anywhere ALLOW OUT Anywhere on tun0 (out)

xxxxx on tun0 ALLOW IN Anywhere

 

xxxxx stands for the port I'm forwarding.

 

When the firewall start, I try to reach a website, I get the message on the command line:

 

write UDPv4: Operation not permitted (code=1)

 

The message usually repeats many times. Then I turn off the firewall, refresh the website (it works), then I turn on the firewall, and now it's fine. Once it works, it will be fine indefinitely.

 

It seems that there is a necessary initial communication that I block. What is it, and how to allow it? I looked at many guides (there are many on these forums), but they seem to suggest the same thing that I do except for a few things, like allowing connection to Airvpn servers for the purpose of reconnecting in case of dropped connection, or allowing local networking. I don't need any of those per se.

 

Thanks in advance,

[j1smith 0]

Nobody knows? This is completely consistence and it seems to happen predictably every single time.

[j1smith 0]

Very surprisingly today it worked on the first attempt. I'll keep talking with myself in this thread.