OpenVPN+frp突破内网限制

在有些办公场景中，我们需要有一根VPN连接到办公室的网络上，这样便于操作办公室的电脑。经过测试了两款VPN软件后，还是选择了openvpn，但是frp+openvpn有一个特殊要求，即公网的服务器带宽越大越好，1M的VPS实在是太痛苦了，不过聊胜于无啊。

下面就是配置过程，请看。

生成证书

三种证书，服务器证书，客户端证书，openvpn密钥

init-config.bat # init-config 会把 vars.bat.sample 复制为 var.bat vars.bat # vars.bat 用来设置一些变量，主要就是配置文件中修改的那部分 clean-all.bat # 会清掉 C: \Program File\OpenVPN\easy-rsa\keys 目录，再把 index.txt 和 serial 文件放进来。 build-ca.bat # 生成根证书 build-dh.bat # 生成 dh1024.pem 文件，Server 使用 TLS(OpenSSL) 必须要有的文件 build-key-server.bat server01 # 生成服务端密钥和证书 # server01 是自己定义的参数名，与上相应的就会生成 server01.key、server01.csr 和 server01.crt，也都是在 keys 目录里。 # 这一步像 build-dh.bat 一样有些东西要填写，之后就是该回答 y 的 y 一下，关键就一个： # Common Name 必须填，且不能与执行 build-dh 时相同，否则会报： # failed to update database # TXT_DB error number 2 # 找不到 C:\Program Files\OpenVPN\easy-rsa\keys\*.old # 三个文件 server01.key、server01.csr 和 server01.crt 也会生成，但文件 server01.crt 的大小是 0 字节无效的，就要重新再来，看到 Data Base Updated 才行。 # 要生成多个服务端的密钥和证书则继续 build-key-server server02 ...... build-key.bat client #客户端生成密钥和证书 # 与build-ca和build-key-server一样要输入一堆东西，这里注意的是 Common Name 不能与执行 build-key-server 时输入的一样，否则也是报： # failed to update database # TXT_DB error number 2 # 找不到 C:\Program Files\OpenVPN\easy-rsa\keys\*.old # 要生成其他的客户端密钥和证书，可以继续 build-key.bat client02 ...... # 生成 ta.key 文件 ..\bin\openvpn --genkey --secret keys\ta.key

服务端配置

将ca.crt、ca.key、server01.crt、server01.csr、server01.key、dh2048.pem、ta.key复制到$OPENVPN/config目录中，配置server.opvn。

配置文件样例

################################################# # Sample OpenVPN 2.0 config file for # # multi-client server. # # # # This file is for the server side # # of a many-clients <-> one-server # # OpenVPN configuration. # # # # OpenVPN also supports # # single-machine <-> single-machine # # configurations (See the Examples page # # on the web site for more info). # # # # This config should work on Windows # # or Linux/BSD systems. Remember on # # Windows to quote pathnames and use # # double backslashes, e.g.: # # "C:\\Program Files\\OpenVPN\\config\\foo.key" # # # # Comments are preceded with '#' or ';' # ################################################# # 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. # Note that v2.4 client/server will automatically # negotiate AES-256-GCM in TLS mode. # See also the ncp-cipher option in the manpage cipher AES-256-CBC # Enable compression on the VPN link and push the # option to the client (v2.4+ only, for earlier # versions see below) ;compress lz4-v2 ;push "compress lz4-v2" # For compression compatible with older clients use comp-lzo # 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 nobody # 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 # Notify the client that when the server restarts so it # can automatically reconnect. explicit-exit-notify 1

客户端配置

将client01.crt、client01.csr、client01.key、ca.key、ca.crt、ta.key文件复制到客户端的$OPENVPN/config目录中，配置client.ovpn文件。

客户端样例配置文件：

############################################## # 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 my-server-1 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 nobody # 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 client.crt key client.key # Verify server certificate by checking that the # certicate has the correct key usage set. # 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 keyUsage set to # digitalSignature, keyEncipherment # and the extendedKeyUsage to # serverAuth # EasyRSA can do this for you. remote-cert-tls 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. # Note that v2.4 client/server will automatically # negotiate AES-256-GCM in TLS mode. # See also the ncp-cipher option in the manpage cipher AES-256-CBC # 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

路由转发

windows

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters 将IPEnableRouter改为1

关闭防火墙或将服务端口加入到防火墙允许通过的端口中。

Linux

/etc/sysctl.d/99-sysctl.conf 增加 net.ipv4.ip_forward=1

其他事项

在windows下，我发现在生成证书的时候，会报如下的错误：

TLS: Initial packet from [AF_INET]xxx:52354, sid=1ca6d405 99996881 VERIFY ERROR: depth=0, error=CRL signature failure: C=CN, ST=BJ, L=Beijin …. OpenSSL: error:140890B2:SSL routines:SSL3_GET_CLIENT_CERTIFICATE:no certificate returned

原因: openssl 或者 openvpn 不支持md5，需要换成sha1或者sha256。
解决办法：

方法一：

修改openssl-1.0.0.cnf，并重新生成crl证书。

default_md = md5

改成

default_md = sha256

生成crl的命令：

openssl ca -gencrl -out keys/crl.pem -config openssl-1.0.0.cnf //revoke-full 脚本是调用的上面的命令

查看crl的命令：

openssl crl -text -in keys/crl.pem

方法二：

添加环境变量，允许MD5算法，然后重启openvpn

NSS_HASH_ALG_SUPPORT=+MD5 OPENSSL_ENABLE_MD5_VERIFY=1