The simplest case if you set up a VPN connection using the Network Manager inside one of your VMs. Setting up such a connection is really not Qubes specific and it is documented in Your Operating system documentation. If you using the Qubes default Guest OS (Fedora): [Establishing a VPN Connection](http://docs.fedoraproject.org/en-US/Fedora/18/html/System_Administrators_Guide/sec-Establishing_a_VPN_Connection.html)
The Qubes specific part is choose the right VM for the VPN client:
### NetVM
The simplest case if you set up a VPN connection using the Network Manager inside your NetVM. Because the [NetworkManager?](/wiki/NetworkManager) already started you are ready to set up your VPN connection. However this has some disadvantages:
- You have to place (and probably save) Your VPN credentials inside the NetVM wich is directly connected to the outside world
- All your AppVMs wich are connected to the NetVM will be connected to the VPN (by default)
While the Network Manager is not started here (for a good reason) You can configure any kind of VPN client in your AppVM as well, however it is only suggested if you have to use a special VPN client.
**WARNING:** *Currently the [NetworkManager?](/wiki/NetworkManager) is not working in ProxyVMs as expected. Actually it will mess up the routing table and because of that your packets may not be routed to the VPN tunnel. - This surely occurs if your VPN wants to be the default gateway.*
One of the best thing in Qubes that you can use a special type of VMs called ProxyVM (or FirewallVM). The special thing is that your AppVMs see this as a NetVM, and the NetVMs see it as an AppVM. Because of that You can place a ProxyVM between your AppVMs and Your NetVM. This is how the default firewall VM is working.