Linux - OpenVPN

$ su

Ubuntu / Linux Mint / Debian
$ apt-get install openvpn network-manager-openvpn network-manager-openvpn-gnome

Fedora
$ dnf install openvpn NetworkManager-openvpn NetworkManager-openvpn-gnome

CentOS 7
$ yum install http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
$ yum install openvpn NetworkManager-openvpn NetworkManager-openvpn-gnome

OpenSUSE
$ zypper install openvpn NetworkManager-openvpn NetworkManager-openvpn-gnome

输入 OpenVPN 配置文件, 连接 VPN
$ openvpn --config '/home/username/Downloads/?.ovpn'
或
可到系统的网络连接设置处加入
All Settings - Hardware - Network - Add Network Connection - VPN - Import from file...
(以 Ubuntu 16.04 为例, 其它 Linux 也差不多)