按照官方 VPN 页面上的说明（说明安装 openvpn 客户端）进行第二步：
# curl -fsSL https://swupdate.openvpn.net/repos/openvpn-repo-pkg-key.pub | gpg --dearmor > /etc/apt/trusted.gpg.d/openvpn-repo-pkg-keyring.gpg
我收到以下错误消息：
sudo curl -fsSL https://swupdate.openvpn.net/repos/openvpn-repo-pkg-key.pub | gpg --dearmor > /etc/apt/trusted.gpg.d/openvpn-repo-pkg-keyring.gpg
-bash: /etc/apt/trusted.gpg.d/openvpn-repo-pkg-keyring.gpg: Permission denied
(23) Failed writing body