我在远程云服务器上设置了一个 OpenVPN 服务器，并配置了所有到位于同一 OpenVPN 服务器上的 dnsmasq 的路由。然后，我在本地笔记本电脑中下载了所有 ca 和客户端密钥。一旦笔记本电脑连接到远程 OpenVPN 服务器，我将使用 OpenVPN 服务器上的 DNS 服务器，然后所有网络连接都将通过 OpenVPN 服务器。
只有在我家时一切正常。但是，当我搬到另一个地方（例如大学办公室）时，所有网站都无法显示。例如，pingwww.google.com控制台失败，而 ping 其 IP 地址则正常。
hijiex@shijie-ThinkPad-T410:/other/dropxbox/Dropbox/project/IPRent/aliyun-us$ ping www.google.com
ping: unknown host www.google.com
shijiex@shijie-ThinkPad-T410:/other/dropxbox/Dropbox/project/IPRent/aliyun-us$ ping 199.212.24.179 (google's IP)
PING 199.212.24.179 (199.212.24.179) 56(84) bytes of data.
64 bytes from 199.212.24.179: icmp_seq=1 ttl=51 time=294 ms
shijiex@shijie-ThinkPad-T410:/other/projectbase/dacapo/benchmarks/bms/batik/src/org/dacapo/harness$ ping 10.8.0.1
PING 10.8.0.1 (10.8.0.1) 56(84) bytes of data.
64 bytes from 10.8.0.1: icmp_seq=1 ttl=64 time=38.0 ms
64 bytes from 10.8.0.1: icmp_seq=2 ttl=64 time=37.7 ms
是client.conf
##############################################
# Sample client-side OpenVPN 2.0 config file #
# for connecting to multi-client server. #
# #
# This configuration can be used by multiple #
# clients, however each client should have #
# its own cert and key files. #
# #
# On Windows, you might want to rename this #
# file so it has a .ovpn extension #
##############################################
# Specify that we are a client and that we
# will be pulling certain config file directives
# from the server.
client
# Use the same setting as you are using on
# the server.
# On most systems, the VPN will not function
# unless you partially or fully disable
# the firewall for the TUN/TAP interface.
;dev tap
dev tun
# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel
# if you have more than one. On XP SP2,
# you may need to disable the firewall
# for the TAP adapter.
;dev-node MyTap
# Are we connecting to a TCP or
# UDP server? Use the same setting as
# on the server.
;proto tcp
proto udp
# The hostname/IP and port of the server.
# You can have multiple remote entries
# to load balance between the servers.
remote 47.90.206.48 1194
;remote my-server-2 1194
# Choose a random host from the remote
# list for load-balancing. Otherwise
# try hosts in the order specified.
;remote-random
# Keep trying indefinitely to resolve the
# host name of the OpenVPN server. Very useful
# on machines which are not permanently connected
# to the internet such as laptops.
resolv-retry infinite
# Most clients don't need to bind to
# a specific local port number.
nobind
# Downgrade privileges after initialization (non-Windows only)
;user nobody
;group nogroup
# Try to preserve some state across restarts.
persist-key
persist-tun
# If you are connecting through an
# HTTP proxy to reach the actual OpenVPN
# server, put the proxy server/IP and
# port number here. See the man page
# if your proxy server requires
# authentication.
;http-proxy-retry # retry on connection failures
;http-proxy [proxy server] [proxy port #]
# Wireless networks often produce a lot
# of duplicate packets. Set this flag
# to silence duplicate packet warnings.
;mute-replay-warnings
# SSL/TLS parms.
# See the server config file for more
# description. It's best to use
# a separate .crt/.key file pair
# for each client. A single ca
# file can be used for all clients.
ca ca.crt
cert aliyun-us.crt
key aliyun-us.key
# Verify server certificate by checking
# that the certicate has the nsCertType
# field set to "server". This is an
# important precaution to protect against
# a potential attack discussed here:
# http://openvpn.net/howto.html#mitm
#
# To use this feature, you will need to generate
# your server certificates with the nsCertType
# field set to "server". The build-key-server
# script in the easy-rsa folder will do this.
ns-cert-type server
# If a tls-auth key is used on the server
# then every client must also have the key.
;tls-auth ta.key 1
# Select a cryptographic cipher.
# If the cipher option is used on the server
# then you must also specify it here.
;cipher x
# Enable compression on the VPN link.
# Don't enable this unless it is also
# enabled in the server config file.
comp-lzo
# Set log file verbosity.
verb 3
# Silence repeating messages
;mute 20
我检查了服务器，一切正常。当我将笔记本电脑搬回家时，它又可以正常工作了。
客户端的控制台：
Mon Apr 3 14:41:00 2017 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key
Mon Apr 3 14:41:00 2017 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Mon Apr 3 14:41:00 2017 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key
Mon Apr 3 14:41:00 2017 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Mon Apr 3 14:41:00 2017 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 2048 bit RSA
Mon Apr 3 14:41:00 2017 [server] Peer Connection Initiated with [AF_INET]47.90.206.48:1194
Mon Apr 3 14:41:03 2017 SENT CONTROL [server]: 'PUSH_REQUEST' (status=1)
Mon Apr 3 14:41:05 2017 PUSH: Received control message: 'PUSH_REPLY,redirect-gateway def1 bypass-dhcp,route 10.8.0.1,topology net30,ping 10,ping-restart 120,ifconfig 10.8.0.6 10.8.0.5'
Mon Apr 3 14:41:05 2017 OPTIONS IMPORT: timers and/or timeouts modified
Mon Apr 3 14:41:05 2017 OPTIONS IMPORT: --ifconfig/up options modified
Mon Apr 3 14:41:05 2017 OPTIONS IMPORT: route options modified
Mon Apr 3 14:41:05 2017 ROUTE_GATEWAY 131.202.102.1/255.255.255.0 IFACE=wlan0 HWADDR=00:23:14:40:24:84
Mon Apr 3 14:41:05 2017 TUN/TAP device tun0 opened
Mon Apr 3 14:41:05 2017 TUN/TAP TX queue length set to 100
Mon Apr 3 14:41:05 2017 do_ifconfig, tt->ipv6=0, tt->did_ifconfig_ipv6_setup=0
Mon Apr 3 14:41:05 2017 /sbin/ip link set dev tun0 up mtu 1500
Mon Apr 3 14:41:05 2017 /sbin/ip addr add dev tun0 local 10.8.0.6 peer 10.8.0.5
Mon Apr 3 14:41:05 2017 /sbin/ip route add 47.90.206.48/32 via 131.202.102.1
Mon Apr 3 14:41:05 2017 /sbin/ip route add 0.0.0.0/1 via 10.8.0.5
Mon Apr 3 14:41:05 2017 /sbin/ip route add 128.0.0.0/1 via 10.8.0.5
Mon Apr 3 14:41:05 2017 /sbin/ip route add 10.8.0.1/32 via 10.8.0.5
Mon Apr 3 14:41:05 2017 Initialization Sequence Completed
更新VPN服务器.conf：
# Which local IP address should OpenVPN
# listen on? (optional)
;local a.b.c.d
# Which TCP/UDP port should OpenVPN listen on?
# If you want to run multiple OpenVPN instances
# on the same machine, use a different port
# number for each one. You will need to
# open up this port on your firewall.
port 1194
# TCP or UDP server?
;proto tcp
proto udp
# "dev tun" will create a routed IP tunnel,
# "dev tap" will create an ethernet tunnel.
# Use "dev tap0" if you are ethernet bridging
# and have precreated a tap0 virtual interface
# and bridged it with your ethernet interface.
# If you want to control access policies
# over the VPN, you must create firewall
# rules for the the TUN/TAP interface.
# On non-Windows systems, you can give
# an explicit unit number, such as tun0.
# On Windows, use "dev-node" for this.
# On most systems, the VPN will not function
# unless you partially or fully disable
# the firewall for the TUN/TAP interface.
;dev tap
dev tun
# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel if you
# have more than one. On XP SP2 or higher,
# you may need to selectively disable the
# Windows firewall for the TAP adapter.
# Non-Windows systems usually don't need this.
;dev-node MyTap
# SSL/TLS root certificate (ca), certificate
# (cert), and private key (key). Each client
# and the server must have their own cert and
# key file. The server and all clients will
# use the same ca file.
#
# See the "easy-rsa" directory for a series
# of scripts for generating RSA certificates
# and private keys. Remember to use
# a unique Common Name for the server
# and each of the client certificates.
#
# Any X509 key management system can be used.
# OpenVPN can also use a PKCS #12 formatted key file
# (see "pkcs12" directive in man page).
ca ca.crt
cert server.crt
key server.key # This file should be kept secret
# Diffie hellman parameters.
# Generate your own with:
# openssl dhparam -out dh2048.pem 2048
dh dh2048.pem
# Network topology
# Should be subnet (addressing via IP)
# unless Windows clients v2.0.9 and lower have to
# be supported (then net30, i.e. a /30 per client)
# Defaults to net30 (not recommended)
;topology subnet
# Configure server mode and supply a VPN subnet
# for OpenVPN to draw client addresses from.
# The server will take 10.8.0.1 for itself,
# the rest will be made available to clients.
# Each client will be able to reach the server
# on 10.8.0.1. Comment this line out if you are
# ethernet bridging. See the man page for more info.
server 10.8.0.0 255.255.255.0
# Maintain a record of client <-> virtual IP address
# associations in this file. If OpenVPN goes down or
# is restarted, reconnecting clients can be assigned
# the same virtual IP address from the pool that was
# previously assigned.
ifconfig-pool-persist ipp.txt
# Configure server mode for ethernet bridging.
# You must first use your OS's bridging capability
# to bridge the TAP interface with the ethernet
# NIC interface. Then you must manually set the
# IP/netmask on the bridge interface, here we
# assume 10.8.0.4/255.255.255.0. Finally we
# must set aside an IP range in this subnet
# (start=10.8.0.50 end=10.8.0.100) to allocate
# to connecting clients. Leave this line commented
# out unless you are ethernet bridging.
;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100
# Configure server mode for ethernet bridging
# using a DHCP-proxy, where clients talk
# to the OpenVPN server-side DHCP server
# to receive their IP address allocation
# and DNS server addresses. You must first use
# your OS's bridging capability to bridge the TAP
# interface with the ethernet NIC interface.
# Note: this mode only works on clients (such as
# Windows), where the client-side TAP adapter is
# bound to a DHCP client.
;server-bridge
# Push routes to the client to allow it
# to reach other private subnets behind
# the server. Remember that these
# private subnets will also need
# to know to route the OpenVPN client
# address pool (10.8.0.0/255.255.255.0)
# back to the OpenVPN server.
;push "route 192.168.10.0 255.255.255.0"
;push "route 192.168.20.0 255.255.255.0"
# To assign specific IP addresses to specific
# clients or if a connecting client has a private
# subnet behind it that should also have VPN access,
# use the subdirectory "ccd" for client-specific
# configuration files (see man page for more info).
# EXAMPLE: Suppose the client
# having the certificate common name "Thelonious"
# also has a small subnet behind his connecting
# machine, such as 192.168.40.128/255.255.255.248.
# First, uncomment out these lines:
;client-config-dir ccd
;route 192.168.40.128 255.255.255.248
# Then create a file ccd/Thelonious with this line:
# iroute 192.168.40.128 255.255.255.248
# This will allow Thelonious' private subnet to
# access the VPN. This example will only work
# if you are routing, not bridging, i.e. you are
# using "dev tun" and "server" directives.
# EXAMPLE: Suppose you want to give
# Thelonious a fixed VPN IP address of 10.9.0.1.
# First uncomment out these lines:
;client-config-dir ccd
;route 10.9.0.0 255.255.255.252
# Then add this line to ccd/Thelonious:
# ifconfig-push 10.9.0.1 10.9.0.2
# Suppose that you want to enable different
# firewall access policies for different groups
# of clients. There are two methods:
# (1) Run multiple OpenVPN daemons, one for each
# group, and firewall the TUN/TAP interface
# for each group/daemon appropriately.
# (2) (Advanced) Create a script to dynamically
# modify the firewall in response to access
# from different clients. See man
# page for more info on learn-address script.
;learn-address ./script
# If enabled, this directive will configure
# all clients to redirect their default
# network gateway through the VPN, causing
# all IP traffic such as web browsing and
# and DNS lookups to go through the VPN
# (The OpenVPN server machine may need to NAT
# or bridge the TUN/TAP interface to the internet
# in order for this to work properly).
;push "redirect-gateway def1 bypass-dhcp"
# Certain Windows-specific network settings
# can be pushed to clients, such as DNS
# or WINS server addresses. CAVEAT:
# http://openvpn.net/faq.html#dhcpcaveats
# The addresses below refer to the public
# DNS servers provided by opendns.com.
push "dhcp-option DNS 208.67.222.222"
push "dhcp-option DNS 208.67.220.220"
# Uncomment this directive to allow different
# clients to be able to "see" each other.
# By default, clients will only see the server.
# To force clients to only see the server, you
# will also need to appropriately firewall the
# server's TUN/TAP interface.
;client-to-client
# Uncomment this directive if multiple clients
# might connect with the same certificate/key
# files or common names. This is recommended
# only for testing purposes. For production use,
# each client should have its own certificate/key
# pair.
#
# IF YOU HAVE NOT GENERATED INDIVIDUAL
# CERTIFICATE/KEY PAIRS FOR EACH CLIENT,
# EACH HAVING ITS OWN UNIQUE "COMMON NAME",
# UNCOMMENT THIS LINE OUT.
;duplicate-cn
# The keepalive directive causes ping-like
# messages to be sent back and forth over
# the link so that each side knows when
# the other side has gone down.
# Ping every 10 seconds, assume that remote
# peer is down if no ping received during
# a 120 second time period.
keepalive 10 120
# For extra security beyond that provided
# by SSL/TLS, create an "HMAC firewall"
# to help block DoS attacks and UDP port flooding.
#
# Generate with:
# openvpn --genkey --secret ta.key
#
# The server and each client must have
# a copy of this key.
# The second parameter should be '0'
# on the server and '1' on the clients.
;tls-auth ta.key 0 # This file is secret
# Select a cryptographic cipher.
# This config item must be copied to
# the client config file as well.
;cipher BF-CBC # Blowfish (default)
;cipher AES-128-CBC # AES
;cipher DES-EDE3-CBC # Triple-DES
# Enable compression on the VPN link.
# If you enable it here, you must also
# enable it in the client config file.
comp-lzo
# The maximum number of concurrently connected
# clients we want to allow.
;max-clients 100
# It's a good idea to reduce the OpenVPN
# daemon's privileges after initialization.
#
# You can uncomment this out on
# non-Windows systems.
;user nobody
;group nogroup
# The persist options will try to avoid
# accessing certain resources on restart
# that may no longer be accessible because
# of the privilege downgrade.
persist-key
persist-tun
# Output a short status file showing
# current connections, truncated
# and rewritten every minute.
status openvpn-status.log
# By default, log messages will go to the syslog (or
# on Windows, if running as a service, they will go to
# the "\Program Files\OpenVPN\log" directory).
# Use log or log-append to override this default.
# "log" will truncate the log file on OpenVPN startup,
# while "log-append" will append to it. Use one
# or the other (but not both).
;log openvpn.log
;log-append openvpn.log
# Set the appropriate level of log
# file verbosity.
#
# 0 is silent, except for fatal errors
# 4 is reasonable for general usage
# 5 and 6 can help to debug connection problems
# 9 is extremely verbose
verb 3
# Silence repeating messages. At most 20
# sequential messages of the same message
# category will be output to the log.
;mute 20
;push "redirect-gateway def1" push "dhcp-option DNS 10.8.0.1"
push "redirect-gateway def1 bypass-dhcp"
;push "redirect-gateway def1"
/etc/rc.local：
#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.
iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -s 10.8.0.0/24 -j ACCEPT
iptables -A FORWARD -j REJECT
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE
service dnsmasq restart
exit 0
和 /etc/sysctl.conf： net.ipv4.ip_forward=1
我还在服务器端配置了IP转发规则。
谢谢
答案1
通过删除分号 (;) 来取消注释以下行（这些行已存在于 server.conf 文件的第 111 行）：
# DNS servers provided by opendns.com.
;push "dhcp-option DNS 208.67.222.222"
;push "dhcp-option DNS 208.67.220.220"
在你的 server.conf 文件中。
在家里，您的 DNS 可能是由路由器提供的。
注意，您应该选择一个与远程站点不同的 10.xxx 网络。否则，一切都会混乱。1
）您更新的 server.conf 文件仍然有分号——请将其删除。2
）当给定一个模板时，使用它，不要打乱各行，除非您知道这样做不会导致问题。取消注释 dhcp=-redirect 而不是仅仅将其添加到末尾——我不知道它是否可以遵循 dhpc-option 行，但请进行最少更改以消除可能的问题调查。3
）删除 tls-auth 行上的 ; tls-auth ta.key 0 # This file is secret 4）在 tls-auth 行之后添加 key-direction 0。5
）对于 Ubuntu 客户端，取消注释用户和组。server.conf 和 client.conf 如果您尝试设置 Windows 客户端，则您问错了网站。
答案2
您的/etc/resolv.conf文件定义了计算机应查找的位置以将主机名解析为 IP 地址。基本问题是默认情况下/etc/resolv.conf运行时不会更新。openvpn
以下是修复该问题需要采取的措施。
1.) 将以下内容附加到server.conf您的 OpenVPN 服务器计算机（通常位于/etc/openvpn/server.conf）上的文件中，以便服务器在客户端查找将主机名转换为 IP 地址的位置。
push "dhcp-option DNS 192.168.1.1"
push "dhcp-option DOMAIN mylocaldomain.lan"
2.) 在客户端计算机上安装并使用以下命令resolvconf将标准链接resolv.conf到版本，以获得能够修改的功能resolvconfresolv.conf
sudo apt install resolvconf
sudo mv /etc/resolv.conf /etc/resolv.conf.orig
sudo ln -s /run/resolvconf/resolv.conf /etc/resolv.conf
3.) 将以下内容附加到文件底部，以便在 OpenVPN 服务器连接或断开连接时client.ovpn运行。resolvconf
up /etc/openvpn/update-resolv-conf
down /etc/openvpn/update-resolv-conf
4.) 无论何时运行，openvpn您都必须使用-script-security 2允许openvpn运行的标志resolvconf。这是一个示例调用
sudo openvpn --script-security 2 --config /path/to/client.ovpn
您可以在此处阅读上述说明的更详细版本，其中包含我的（正在运行的）OpenVPN 服务器的一些示例代码：https://steamforge.net/wiki/index.php/How_to_configure_OpenVPN_to_resolve_local_DNS_%26_hostnames