搭建私有CA服务器
CA是什么
CA（Certificate Authority）证书颁发机构主要负责证书的颁发、管理以及归档和吊销。证书内包含了拥有证书者的姓名、地址、电子邮件帐号、公钥、证书有效期、发放证书的CA、CA的数字签名等信息。证书主要有三大功能：加密、签名、身份验证。
centos6.x上有关ssl证书的目录结构如下:
/etc/pki/CA/
├── certs
├── crl 吊销的证书
├── newcerts 存放CA签署（颁发）过的数字证书（证书备份目录）
└── private 用于存放CA的私钥
/etc/pki/tls/
├── cert.pem -> certs/ca-bundle.crt 软链接到certs/ca-bundle.crt
├── certs 该服务器上的证书存放目录，可以放置自己的证书和内置证书
│ ├── ca-bundle.crt 内置信任的证书
│ ├── ca-bundle.trust.crt
│ ├── make-dummy-cert
│ └── Makefile
├── misc
│ ├── CA
│ ├── c_hash
│ ├── c_info
│ ├── c_issuer
│ └── c_name
├── openssl.cnf openssl的CA主配置文件
└── private 证书密钥存放目录
CA要给别人颁发证书，首先自己得有一个作为根证书，我们得在一切工作之前修改好CA的配置文件、序列号、索引等等。
vi /etc/pki/tls/openssl.cnf
一.建立CA服务器
1.生成根密钥
为了安全起见，修改cakey.pem私钥文件权限为600或400，也可以使用子shell生成( umask 077; openssl genrsa -out private/cakey.pem 2048 )，下面不再重复。
cd /etc/pki/CA/
openssl genrsa -out private/cakey.pem 2048
或使用命令
( umask 077; openssl genrsa -out /etc/pki/CA/private/cakey.pem 2048 )
执行结果如下：
[root@localhost CA]# ( umask 077; openssl genrsa -out /etc/pki/CA/private/cakey.pem 2048 )
Generating RSA private key, 2048 bit long modulus
..................+++
...+++
e is 65537 (0x10001)
参数说明：
（）：表示此命令在子进程中运行，其目的是为了不改变当前Shell中的umask值；
genrsa：生成私钥；
-out：私钥的存放路径，cakey.pem：为密钥名，与配置文件中保持一致；
2048：密钥长度，默认为1024。
2.生成根证书
使用req命令生成自签证书：会提示输入一些内容，因为是私有的，所以可以随便输入（之前修改的openssl.cnf会在这里呈现），最好记住能与后面保持一致 自签证书cacert.pem应该生成在/etc/pki/CA下。
openssl req -new -x509 -key /etc/pki/CA/private/cakey.pem -out cacert.pem -days 3650
执行结果如下：
[root@localhost CA]# openssl req -new -x509 -key /etc/pki/CA/private/cakey.pem -out /etc/pki/CA/cacert.pem -days 3650
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.
-----
Country Name (2 letter code) [XX]:CN
State or Province Name (full name) []:beijing
Locality Name (eg, city) [Default City]:beijing
Organization Name (eg, company) [Default Company Ltd]:home
Organizational Unit Name (eg, section) []:homepart
Common Name (eg, your name or your server's hostname) []:home.home
Email Address []:home@home.home
参数说明：
req：生成证书签署请求；
-x509：生成自签署证书；
-days n：证书的有效天数；
-new：新请求；
-key /path/to/keyfile：指定私钥文件；
-out /path/to/somefile：输出文件位置。
3.初始化工作环境
touch /etc/pki/CA/index.txt /etc/pki/CA/serial 创建index.txt,serial文件
echo 01 > /etc/pki/CA/serial
mkdir -p /etc/pki/CA/csr/ 用来存放节点上传过来的csr证书请求目录
index.txt：索引文件，用于匹配证书编号； serial：证书序列号文件，只在首次生成证书时赋值。
二.节点生成证书
以上都是在CA服务器上做的操作，而且只需进行一次，现在转到nginx服务器上执行：
1.生成密钥对：
为我们的nginx web服务器生成ssl密钥
mkdir -p /etc/nginx/ssl
cd /etc/nginx/ssl
(umask 077; openssl genrsa -out /etc/nginx/ssl/nginx.key 2048) 生成私钥
执行结果：
[root@localhost ssl]# (umask 077; openssl genrsa -out /etc/nginx/ssl/nginx.key 2048)
Generating RSA private key, 2048 bit long modulus
..................+++
.................+++
e is 65537 (0x10001)
2.生成证书请求：
为nginx生成证书签署请求
openssl req -new -key /etc/nginx/ssl/nginx.key -out /etc/nginx/ssl/nginx.csr
同样会提示输入一些内容，其它随便，除了Commone Name一定要是你要授予证书的服务器域名或主机名，challenge password不填。
执行结果如下：
[root@localhost ssl]# openssl req -new -key /etc/nginx/ssl/nginx.key -out /etc/nginx/ssl/nginx.csr
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.
-----
Country Name (2 letter code) [XX]:CN
State or Province Name (full name) []:shanghai
Locality Name (eg, city) [Default City]:shanghai
Organization Name (eg, company) [Default Company Ltd]:mycompany
Organizational Unit Name (eg, section) []:tech
Common Name (eg, your name or your server's hostname) []:myweb.com
Email Address []:myweb@myweb.com
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:
3.把签署请求文件发送给CA服务器
接下来要把上一步生成的证书请求csr文件，发到CA服务器上（其中192.168.1.80为CA服务器）
scp /etc/nginx/ssl/nginx.csr 192.168.1.80:/etc/pki/CA/csr/nginx.csr
测试时节点和CA服务器是同一台,故使用如下命令
cp /etc/nginx/ssl/nginx.csr /etc/pki/CA/csr/nginx.csr
三.签署证书
1.在CA服务器上签署证书
私有CA根据请求来签署证书,在CA服务器上执行
openssl ca -in /etc/pki/CA/csr/nginx.csr -out /etc/pki/CA/nginx.crt -days 3650
另外在极少数情况下，上面的命令生成的证书不能识别，试试下面的命令：
# openssl x509 -req -in /etc/pki/CA/csr/nginx.csr -CA /etc/pki/CA/cacert.pem -CAkey /etc/pki/CA/private/cakey.pem -CAcreateserial -out /etc/pki/CA/nginx2.crt
这里出错了,由于根证书是beijing而节点是shanghai
[root@localhost CA]# openssl ca -in /etc/pki/CA/csr/nginx.csr -out /etc/pki/CA/nginx.crt -days 3650
Using configuration from /etc/pki/tls/openssl.cnf
Check that the request matches the signature
Signature ok
The stateOrProvinceName field needed to be the same in the
CA certificate (beijing) and the request (shanghai)
重新生成节点csr证书请求，设置区域为beijing 执行结果如下(成功)：
[root@localhost CA]# openssl ca -in /etc/pki/CA/csr/nginx.csr -out /etc/pki/CA/nginx.crt -days 3650 Using configuration from /etc/pki/tls/openssl.cnf
Check that the request matches the signature
Signature ok
Certificate Details:
Serial Number: 1 (0x1)
Validity
Not Before: Jun 2 10:21:22 2017 GMT
Not After : May 31 10:21:22 2027 GMT
Subject:
countryName = CN
stateOrProvinceName = beijing
organizationName = home
organizationalUnitName = home
commonName = *.test.com
emailAddress = my@test.com
X509v3 extensions:
X509v3 Basic Constraints:
CA:FALSE
Netscape Comment:
OpenSSL Generated Certificate
X509v3 Subject Key Identifier:
96:D7:60:53:1E:52:3E:89:4F:A0:A4:3D:81:CA:97:D5:D8:67:AE:93
X509v3 Authority Key Identifier:
keyid:D5:71:B2:72:16:62:03:09:BB:6D:B2:14:5F:F2:3C:B5:AE:C1:BD:08
Certificate is to be certified until May 31 10:21:22 2027 GMT (3650 days)
Sign the certificate? [y/n]:y
1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated
上面签发过程其实默认使用了-cert cacert.pem -keyfile cakey.pem，这两个文件就是前两步生成的位于/etc/pki/CA下的根密钥和根证书。
2.将crt证书发送给请求者
将生成的crt证书发回nginx服务器使用。192.168.137.61为nginx服务器地址
scp /etc/pki/CA/csr/nginx.crt 192.168.137.61:/etc/nginx/ssl/
同一台本机使用
cp /etc/pki/CA/nginx.crt /etc/nginx/ssl/
到此我们已经拥有了建立ssl安全连接所需要的所有文件，并且服务器的crt和key都位于配置的目录下，剩下的是如何使用证书的问题。
四.吊销证书
1.节点请求吊销
[root@localhost CA]# openssl x509 -in /etc/nginx/ssl/nginx.crt -noout -serial -subject
serial=01
subject= /C=CN/ST=beijing/O=home/OU=home/CN=*.test.com/emailAddress=my@test.com
参数说明:
x509：证书格式
-in：要吊销的证书
-noout：不输出额外信息
-serial：显示序列号
-subject：显示subject信息
2.CA验证信息
2.1 节点提交的serial和subject信息来验证与index.txt文件中的信息是否一致
[root@localhost CA]# cat /etc/pki/CA/index.txt
V 270531102122Z 01 unknown /C=CN/ST=beijing/O=home/OU=home/CN=*.17coolz.com/emailAddress=my@test.com
2.2 吊销证书
openssl ca -revoke /etc/pki/CA/newcerts/01.pem
参数说明 -revoke：删除证书。 执行结果
[root@localhost CA]# openssl ca -revoke /etc/pki/CA/newcerts/01.pem
Using configuration from /etc/pki/tls/openssl.cnf
Revoking Certificate 01.
Data Base Updated
2.3 查看被吊销的证书列表
[root@localhost CA]# cat /etc/pki/CA/index.txt
R 270531102122Z 170602103652Z 01 unknown /C=CN/ST=beijing/O=home/OU=home/CN=*.17coolz.com/emailAddress=my@test.com
2.4 生成吊销证书的编号（如果是第一次吊销）
echo 00 > /etc/pki/CA/crlnumber
2.5 更新证书吊销列表
openssl ca -gencrl -out /etc/pki/CA/crl/ca.crl
执行结果：
[root@localhost CA]# openssl ca -gencrl -out /etc/pki/CA/crl/ca.crl
Using configuration from /etc/pki/tls/openssl.cnf
2.6 查看吊消crl文件内容
openssl crl -in crl/ca.crl -noout -text
执行结果
[root@localhost CA]# openssl crl -in /etc/pki/CA/crl/ca.crl -noout -text
Certificate Revocation List (CRL):
Version 2 (0x1)
Signature Algorithm: sha1WithRSAEncryption
Issuer: /C=CN/ST=beijing/L=beijing/O=home/OU=homepart/CN=home.home/emailAddress=home@home.home
Last Update: Jun 2 10:41:24 2017 GMT
Next Update: Jul 2 10:41:24 2017 GMT
CRL extensions:
X509v3 CRL Number:
0
Revoked Certificates:
Serial Number: 01
Revocation Date: Jun 2 10:36:52 2017 GMT
Signature Algorithm: sha1WithRSAEncryption
a3:fc:cf:fd:08:44:d9:c0:fd:78:75:5f:79:3a:c3:16:17:da:
b8:b1:cc:d8:67:28:73:75:4a:e1:11:e3:04:de:0a:36:4f:d6:
de:ec:37:3b:0b:18:0f:24:18:d1:8b:c9:6a:f8:e0:d3:c6:cc:
42:67:5b:15:34:da:f9:49:eb:19:73:33:4e:ef:eb:cb:82:12:
4c:27:ee:5e:9d:50:5f:8b:0c:51:3a:05:e3:0f:fb:3c:0d:0b:
8e:af:17:5e:b2:7d:30:af:e6:60:f2:6e:7f:b5:b5:9b:b1:f7:
5e:d4:80:73:d3:cc:30:e1:78:71:db:81:a0:ad:49:6a:dc:5c:
12:bf:31:0f:11:59:54:80:e9:74:36:f7:98:e2:86:f2:29:3f:
b0:69:b8:a4:32:9d:1c:61:01:ed:0f:09:b0:10:be:f4:07:ac:
32:91:9c:cc:35:cf:c3:cb:44:6b:86:22:81:7d:7a:71:9d:5c:
34:da:30:47:5a:ce:0f:10:bc:2a:56:8f:41:85:de:95:48:5c:
d3:b2:90:ae:4f:7e:7c:d1:53:5c:6f:67:cb:aa:cc:78:5b:1a:
f6:31:5b:7e:04:03:73:da:6e:8d:00:d7:bf:db:75:6a:0e:44:
be:c1:20:0f:72:40:4c:29:fc:aa:87:30:9e:84:55:e1:76:a2:
00:05:39:18
参数说明
-text：以文本形式显示。
后话
如果你要自己做CA，别忘了客户端需要导入CA的证书（CA的证书是自签名的，导入它意味着你“信任”这个CA签署的证书）。而商业CA的一般不用，因为它们已经内置在你的浏览器中了。
参考：
http://www.178linux.com/12742
http://www.cnblogs.com/zhaojiedi1992/p/zhaojiedi_linux_011_ca.html
http://seanlook.com/2015/01/18/openssl-self-sign-ca/