所以我通过以下方式从 Ubuntu 16.04 连接到 VPN 服务器
$ sudo openvpn client.ovpn
并且 client.ovpn 以以下内容开头
# Automatically generated OpenVPN client config file
# Generated on Mon Jun 6 10:36:29 2016 by openvpnas
# Note: this configuration is user-locked to the username below
...
# OVPN_ACCESS_SERVER_CLI_PREF_ALLOW_WEB_IMPORT=True
# OVPN_ACCESS_SERVER_CLI_PREF_BASIC_CLIENT=False
# OVPN_ACCESS_SERVER_CLI_PREF_ENABLE_CONNECT=True
# OVPN_ACCESS_SERVER_CLI_PREF_ENABLE_XD_PROXY=True
...
# OVPN_ACCESS_SERVER_WEB_CA_BUNDLE_START
# -----BEGIN CERTIFICATE-----
...
# -----END CERTIFICATE-----
# OVPN_ACCESS_SERVER_WEB_CA_BUNDLE_STOP
# OVPN_ACCESS_SERVER_IS_OPENVPN_WEB_CA=1
# OVPN_ACCESS_SERVER_ORGANIZATION=OpenVPN Technologies, Inc.
setenv FORWARD_COMPATIBLE 1
client
server-poll-timeout 4
nobind
...
dev tun
dev-type tun
ns-cert-type server
reneg-sec 604800
sndbuf 100000
rcvbuf 100000
auth-user-pass
# NOTE: LZO commands are pushed by the Access Server at connect time.
# NOTE: The below line doesn't disable LZO.
comp-lzo no
verb 3
setenv PUSH_PEER_INFO
连接会在 24 小时后自动终止。如何使它持久？有没有可以传递给的选项openvpn？