centos下openvpn安装与配置

安装软件包

环境就是新装 CentOS7.4，使用阿里云的 epel 源和常规源，不知道别的源有没有更新这个包，不废话，直接安装软件包。

[root@localhost ~]# yum -y install openvpn easy-rsa

配置 easy-rsa-3.0

复制文件

[root@localhost ~]# cp -r /usr/share/easy-rsa/ /etc/openvpn/easy-rsa
[root@localhost ~]# cd /etc/openvpn/easy-rsa/
[root@localhost easy-rsa]# 
m 3 3.0
[root@localhost easy-rsa]# cd 3.0.3/
[root@localhost 3.0.3]# find / -type f -name "vars.example" | xargs -i cp {} . && mv vars.example vars

这里说明一下，正常来说 easy-rsa-3.0.3 安装完之后，vars.example 文件在 /usr/share/doc/easy-rsa-3.0.3/ 目录，至于有些人说找不到这个文件，我暂时还没遇到过，可能你的安装方式和我不一致，或版本不同，不做深究。

创建一个新的 PKI 和 CA

[root@localhost 3.0.3]# pwd
/etc/openvpn/easy-rsa/3.0.3
[root@localhost 3.0.3]# ./easyrsa init-pki  #创建空的pki

Note: using Easy-RSA configuration from: ./vars

init-pki complete; you may now create a CA or requests.
Your newly created PKI dir is: /etc/openvpn/easy-rsa/3.0.3/pki

[root@localhost 3.0.3]# ./easyrsa build-ca nopass #创建新的CA，不使用密码

Note: using Easy-RSA configuration from: ./vars
Generating a 2048 bit RSA private key
......................+++
................................................+++
writing new private key to '/etc/openvpn/easy-rsa/3.0.3/pki/private/ca.key.pClvaQ1GLD'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Common Name (eg: your user, host, or server name) [Easy-RSA CA]: 回车

CA creation complete and you may now import and sign cert requests.
Your new CA certificate file for publishing is at:
/etc/openvpn/easy-rsa/3.0.3/pki/ca.crt

创建服务端证书

[root@localhost 3.0.3]# ./easyrsa gen-req server nopass

Note: using Easy-RSA configuration from: ./vars
Generating a 2048 bit RSA private key
...........................+++
..............................................................................+++
writing new private key to '/etc/openvpn/easy-rsa/3.0.3/pki/private/server.key.wy7Q0fuG6A'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Common Name (eg: your user, host, or server name) [server]: 回车

Keypair and certificate request completed. Your files are:
req: /etc/openvpn/easy-rsa/3.0.3/pki/reqs/server.req
key: /etc/openvpn/easy-rsa/3.0.3/pki/private/server.key

签约服务端证书

[root@localhost 3.0.3]# ./easyrsa sign server server

Note: using Easy-RSA configuration from: ./vars


You are about to sign the following certificate.
Please check over the details shown below for accuracy. Note that this request
has not been cryptographically verified. Please be sure it came from a trusted
source or that you have verified the request checksum with the sender.

Request subject, to be signed as a server certificate for 3650 days:

subject=
    commonName                = server


Type the word 'yes' to continue, or any other input to abort.
  Confirm request details: yes
Using configuration from ./openssl-1.0.cnf
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
commonName            :ASN.1 12:'server'
Certificate is to be certified until Apr  7 14:54:08 2028 GMT (3650 days)

Write out database with 1 new entries
Data Base Updated

Certificate created at: /etc/openvpn/easy-rsa/3.0.3/pki/issued/server.crt

创建 Diffie-Hellman

[root@localhost 3.0.3]# ./easyrsa gen-dh
............................................................
DH parameters of size 2048 created at /etc/openvpn/easy-rsa/3.0.3/pki/dh.pem

到这里服务端的证书就创建完了，然后创建客户端的证书。

创建客户端证书

复制文件

[root@localhost ~]# cp -r /usr/share/easy-rsa/ /etc/openvpn/client/easy-rsa
[root@localhost ~]# cd /etc/openvpn/client/easy-rsa/
[root@localhost easy-rsa]# 
m 3 3.0 
[root@localhost easy-rsa]# cd 3.0.3/
[root@localhost 3.0.3]# find / -type f -name "vars.example" | xargs -i cp {} . && mv vars.example vars

生成证书

[root@localhost 3.0.3]# pwd
/etc/openvpn/client/easy-rsa/3.0.3
[root@localhost 3.0.3]# ./easyrsa init-pki #创建新的pki

Note: using Easy-RSA configuration from: ./vars

init-pki complete; you may now create a CA or requests.
Your newly created PKI dir is: /etc/openvpn/client/easy-rsa/3.0.3/pki
[root@localhost 3.0.3]# ./easyrsa gen-req dalin nopass  #客户证书名为大林，木有密码

Note: using Easy-RSA configuration from: ./vars
Generating a 2048 bit RSA private key
....................................................+++
............+++
writing new private key to '/etc/openvpn/client/easy-rsa/3.0.3/pki/private/dalin.key.FkrLzXH9Bm'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Common Name (eg: your user, host, or server name) [dalin]: 回车

Keypair and certificate request completed. Your files are:
req: /etc/openvpn/client/easy-rsa/3.0.3/pki/reqs/dalin.req
key: /etc/openvpn/client/easy-rsa/3.0.3/pki/private/dalin.key

最后签约客户端证书

[root@localhost 3.0.3]# cd /etc/openvpn/easy-rsa/3.0.3/
[root@localhost 3.0.3]# pwd
/etc/openvpn/easy-rsa/3.0.3
[root@localhost 3.0.3]# ./easyrsa import-req /etc/openvpn/client/easy-rsa/3.0.3/pki/reqs/dalin.req dalin

Note: using Easy-RSA configuration from: ./vars

The request has been successfully imported with a short name of: dalin
You may now use this name to perform signing operations on this request.

[root@localhost 3.0.3]# ./easyrsa sign client dalin

Note: using Easy-RSA configuration from: ./vars


You are about to sign the following certificate.
Please check over the details shown below for accuracy. Note that this request
has not been cryptographically verified. Please be sure it came from a trusted
source or that you have verified the request checksum with the sender.

Request subject, to be signed as a client certificate for 3650 days:

subject=
    commonName                = dalin


Type the word 'yes' to continue, or any other input to abort.
  Confirm request details: yes
Using configuration from ./openssl-1.0.cnf
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
commonName            :ASN.1 12:'dalin'
Certificate is to be certified until Apr  8 01:54:57 2028 GMT (3650 days)

Write out database with 1 new entries
Data Base Updated

Certificate created at: /etc/openvpn/easy-rsa/3.0.3/pki/issued/dalin.crt

整理证书展开目录

现在所有的证书都已经生成完了，下面来整理一下。

服务端所需要的文件展开目录

[root@localhost ~]# mkdir /etc/openvpn/certs
[root@localhost ~]# cd /etc/openvpn/certs/  
[root@localhost certs]# cp /etc/openvpn/easy-rsa/3.0.3/pki/dh.pem .        
[root@localhost certs]# cp /etc/openvpn/easy-rsa/3.0.3/pki/ca.crt .
[root@localhost certs]# cp /etc/openvpn/easy-rsa/3.0.3/pki/issued/server.crt .
[root@localhost certs]# cp /etc/openvpn/easy-rsa/3.0.3/pki/private/server.key .
[root@localhost certs]# ll
总用量 20
-rw-------. 1 root root 1172 4月  11 10:02 ca.crt
-rw-------. 1 root root  424 4月  11 10:03 dh.pem
-rw-------. 1 root root 4547 4月  11 10:03 server.crt
-rw-------. 1 root root 1704 4月  11 10:02 server.key

客户端所需的文件展开目录

[root@localhost certs]# mkdir /etc/openvpn/client/dalin/
[root@localhost certs]# cp /etc/openvpn/easy-rsa/3.0.3/pki/ca.crt /etc/openvpn/client/dalin/
[root@localhost certs]# cp /etc/openvpn/easy-rsa/3.0.3/pki/issued/dalin.crt /etc/openvpn/client/dalin/
[root@localhost certs]# cp /etc/openvpn/client/easy-rsa/3.0.3/pki/private/dalin.key /etc/openvpn/client/dalin/
[root@localhost certs]# ll /etc/openvpn/client/dalin/
总用量 16
-rw-------. 1 root root 1172 4月  11 10:07 ca.crt
-rw-------. 1 root root 4431 4月  11 10:08 dalin.crt
-rw-------. 1 root root 1704 4月  11 10:08 dalin.key

其实这三个文件就够了，之前全下载下来是因为方便，然而这次懒得弄了，哈哈，编写服务端配置文件。顺便提一下再添加用户在./easyrsa gen-req 这里开始就行了，像是吊销用户证书的命令都自己用./easyrsa --help 去看吧，GitHub 项目地址

服务器配置文件展开目录

[root@localhost ~]# vim /etc/openvpn/server.conf
port 1194
proto udp
dev tun
ca /etc/openvpn/certs/ca.crt
cert /etc/openvpn/certs/server.crt
key /etc/openvpn/certs/server.key # This file should be kept secret
dh /etc/openvpn/certs/dh.pem
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
#push "redirect-gateway def1 bypass-dhcp"
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 208.67.220.220"
keepalive 10 120
tls-auth ta.key 0 # This file is secret
cipher AES-256-CBC
#comp-lzo
max-clients 100
persist-key
persist-tun
status openvpn-status.log
verb 3
explicit-exit-notify 1
tun-mtu 1500

启动服务展开目录

启动服务

[root@localhost ~]# systemctl start openvpn@server

然后接下来的请看这里吧，从配置 iptables 及转发开始，懒得写了。

客户端配置文件

client
proto udp
dev tun
dev-node tun0
remote myserver.com 1194
resolv-retry infinite
nobind
persist-key
persist-tun
ca ca.crt
cert zhouhui.crt
key zhouhui.key
remote-cert-tls server
tls-auth ta.key 1
cipher AES-256-CBC
verb 3
tun-mtu 1500
tun-mtu-extra 32

吊销证书展开目录

最近被游客问到如何去吊销证书，所以在这里就加一下，正常情况下证书就是一人一个，下面栗子，注销名为 dalin 的证书。

[root@openvpn ~]# cd /etc/openvpn/easy-rsa/
[root@openvpn easy-rsa]# ./easyrsa revoke dalin

Note: using Easy-RSA configuration from: ./vars


Please confirm you wish to revoke the certificate with the following subject:

subject= 
    commonName                = dalin


Type the word 'yes' to continue, or any other input to abort.
  Continue with revocation: yes
Using configuration from /etc/openvpn/easy-rsa/openssl-1.0.cnf
Revoking Certificate 06.
Data Base Updated

IMPORTANT!!!

Revocation was successful. You must run gen-crl and upload a CRL to your
infrastructure in order to prevent the revoked cert from being accepted.

[root@openvpn easy-rsa]# ./easyrsa gen-crl

Note: using Easy-RSA configuration from: ./vars
Using configuration from /etc/openvpn/easy-rsa/openssl-1.0.cnf

An updated CRL has been created.
CRL file: /etc/openvpn/easy-rsa/pki/crl.pem

执行上述命令后用户证书不会被删除，只是更新了 crl.pem 文件，可以看到上面的提示，文件位置在 /etc/openvpn/easy-rsa/pki/crl.pem，查看所有证书的的信息，阔以这样去看。

[root@openvpn easy-rsa]# find /etc/openvpn/ -type f -name "index.txt" | xargs cat
V    280825082643Z        01    unknown    /CN=server
R    280826061455Z    181211135800Z    03    unknown    /CN=dalin

列举了两个作对比，V 为可用，R 为注销，现在 dalin 的证书还是能连接到服务器，现在需要告知服务端 crl.pem 的位置，下面修改配置文件。

[root@openvpn easy-rsa]# vim /etc/openvpn/server.conf
crl-verify /etc/openvpn/easy-rsa/pki/crl.pem
[root@openvpn easy-rsa]# systemctl restart openvpn@server

这样就可以了，dalin 现在就无法连接到服务器了，服务端日志。