Hi there, also from Iran
With your package manager install the following:
networkmanager networkmanager-openconnect networkmanager-qt(or gnome)
After that there should be an app installed called "Advanced Network Configuration", with which you can add pretty much any network profile you want.
At the moment I don't know of any "pretty" GUI's to connect to them, but you can type
nmtui in your terminal and you should see a screen where you can "activate a network" (connect to a network). Just follow the instructions and you should be able to connect to your VPN of choice pretty easily.
Hope this was helpful, if you need further help, please don't hesitate to ask.