1. yum -y install openvpn
    2. cd /etc/openvpn/client
    3. 将openvpn客户端连接文件client.ovpn上传至/etc/openvpn/client下
    4. 启动：
    5. openvpn --daemon --cd /etc/openvpn/client --config client.ovpn --log-append /var/log/openvpn.log