Getting "Cannot ioctl TUNSETIFF tun: Operation not permitted" when trying to connect to OpenVPN

Solution 1:

Looks like this is a simple matter of sudo.

sudo openvpn client.ovpn worked a treat.

Solution 2:

Creating the TUN or TAP adaptor requires privileges that you possibly don't have - hence the command works with sudo, but not without.

On my system, if the openvpn command is run like this;

sudo openvpn --config file.ovpn

then a device tun0 is created. Almost always, creating devices requires privileges.