环境

服务器使用树莓派3b+，操作系统选FreeBSD14.1，由于FreeBSD无法识别树莓派的WiFi，只能使用有线网络。

环境服务器端准备工作初始化生成CA制作服务器证书制作加密材料制作dh.pem创建服务器端配置文件编辑/etc/rc.conf以启动openvpn服务服务器启用NAT客户端制作客户端证书和密钥对制作客户端配置文件配置文件示例server.conf 内容如下client.conf 内容如下

服务器端

准备工作


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$ mkdir ~/easy-rsa
$ ln -s /usr/local/share/easy-rsa/* ~/easy-rsa/
$ sudo chown lidapeng ~/easy-rsa
$ chmod 700 ~/easy-rsa

注意：以后所有工作都在 /home/lidapeng/easy-rsa/ 目录下完成。

初始化

进入 /home/lidapeng/easy-rsa/ 目录，先运行 easyrsa init-pki 行初始化，然后创建 vars 文件，内容如下：


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set_var EASYRSA_REQ_COUNTRY    "CN"
set_var EASYRSA_REQ_PROVINCE   "GuangDong"
set_var EASYRSA_REQ_CITY       "Guangzhou"
set_var EASYRSA_REQ_ORG        "dapeng.li"
set_var EASYRSA_REQ_EMAIL      "lidapeng@dapeng.li"
set_var EASYRSA_REQ_OU         "Community"
set_var EASYRSA_REQ_CN         "p3b.dapeng.li"
set_var EASYRSA_ALGO           "ec"
set_var EASYRSA_DIGEST         "sha512"

生成CA

运行以下命令：


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$ easyrsa bulid-ca nopass

命令执行完成后会生成两个文件：

~/easy-rsa/pki/ca.crt
~/easy-rsa/pki/private/ca.key

创建目录 /usr/local/etc/openvpn/ ，并将ca.crt复制该目录中。


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$ sudo mkdir /usr/local/etc/openvpn
$ sudo cp pki/ca.crt /usr/local/etc/openvpn/

制作服务器证书

执行以下命令生成服务器私钥（pki/private/server.key）和证书请求文件（pki/reqs/server.req）：


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$ easyrsa gen-req server nopass

执行以下命令生成服务器证书（pki/issued/server.crt）：


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$ easyrsa sign-req server server

将以上server.crt和server.key复制到 /usr/local/etc/openvpn/ 目录中，以便openvpn服务启动时找到它们。

制作加密材料

运行以下命令生成ta.key，并将其复制到 /usr/local/etc/openvpn/ 目录中：


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$ openvpn --genkey secret ta.key
$ sudo cp tar.key /usr/local/etc/openvpn/

制作dh.pem

运行以下命令生成dh.pem，并将其复制到 /usr/local/etc/openvpn/ 目录中：


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$ easyrsa gen-dh
$ sudo cp pki/dh.pem /usr/local/etc/openvpn/

创建服务器端配置文件

/usr/local/etc/openvpn/server.conf ，内容如下：


x
port 19
proto udp
dev tun
ca ca.crt
cert server.crt
key server.key
dh dh.pem
tls-crypt ta.key
comp-lzo
server 10.8.0.0 255.255.255.0
push "redirect-gateway local def1 bypass-dns"
push "dhcp-option DNS 8.8.8.8"
duplicate-cn
log-append /var/log/openvpn/openvpn.log
topology subnet
persist-key
persist-tun
keepalive 10 60
cipher AES-256-GCM
verb 3
daemon
user nobody
group nogroup

编辑/etc/rc.conf以启动openvpn服务

添加以下行：


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openvpn_enable="yes"
openvpn_if="tun"
openvpn_configfile="/usr/local/etc/openvpn/server.conf"

服务器启用NAT

编辑 /boot/loader.conf ，加入以下内容：


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net.inet.ip.fw.default_to_accept="1"

编辑/etc/rc.conf，加入以下内容：


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firewall_enable="YES"
firewall_type="open"
gateway_enable="YES"
natd_enalbe="YES"
natd_interface="ue0"
natd_flags="-dynamic -m"

完成后重启。

客户端

制作客户端证书和密钥对

在 /home/lidapeng/easy-rsa 目录中运行以下命令：


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$ easyrsa gen-req client1 nopass
$ easyrsa sign-req client client1

制作客户端配置文件

文件名为 client.ovpn ，内容如下：


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client
dev tun
proto tcp
port 19
resolv-retry infinite
nobind
comp-lzo
persist-key
persist-tun
remote 【服务器地址】
<ca>
ca.crt文件中的内容
</ca>
<cert>
clinet1.crt中的内容
</cert>
<key>
clinet1.key中的内容
</key>
<tls-crypt>
ta.key中的内容
</tls-crypt>

配置文件示例

OpenVPN安装后会在 /usr/local/share/examples/openvpn/ 中生成一些配置文件的示例，其中 sample-config-files 里面的 server.conf 和 client.conf 这两个文件可供参考。

server.conf 内容如下


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#################################################
# Sample OpenVPN 2.6 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 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/open
# 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.
# 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" project at
# https://github.com/OpenVPN/easy-rsa
# 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).
#
# If you do not want to maintain a CA
# and have a small number of clients
# you can also use self-signed certificates
# and use the peer-fingerprint option.
# See openvpn-examples man page for a
# configuration example.
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
# Allow to connect to really old OpenVPN versions
# without AEAD support (OpenVPN 2.3.x or older)
# This adds AES-256-CBC as fallback cipher and
# keeps the modern ciphers as well.
;data-ciphers AES-256-GCM:AES-128-GCM:?CHACHA20-POLY1305:AES-256-CBC
# 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
# 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.
;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 tls-auth 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
# 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 on non-Windows
# systems after creating a dedicated user.
;user openvpn
;group openvpn
# 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

client.conf 内容如下


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##############################################
# Sample client-side OpenVPN 2.6 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 openvpn
;group openvpn
# 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
# certificate 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
# Allow to connect to really old OpenVPN versions
# without AEAD support (OpenVPN 2.3.x or older)
# This adds AES-256-CBC as fallback cipher and
# keeps the modern ciphers as well.
;data-ciphers AES-256-GCM:AES-128-GCM:?CHACHA20-POLY1305:AES-256-CBC
# If a tls-auth key is used on the server
# then every client must also have the key.
;tls-auth ta.key 1
# Set log file verbosity.
verb 3
# Silence repeating messages
;mute 20