Openldap配置TLS加密传输

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为啥要用TLS?
Openldap默认使用简单验证，对slapd的所有访问都使用明文密码通过未加密通道进行。为了确保信息安全，需要对信息进行加密传输，SSL（Secure Sockets Layer）是一个可靠的解决方案。
它使用 X.509 证书，由可信任第三方（Certificate Authority (CA)）进行数字签名的一个标准格式的数据。有效的数字签名意味着已签名的数据没有被篡改。如果签名的数据被更改，将不会通过验证
SSL/TLS 加密原理简介
SSL/TLS 是基于 PKI 机制的加密方式，包括证书认证、密钥交换、非对称加密、对称加密。SSL/TLS 采用 CA 作为服务端和客户端都信赖的具有权威性的组织，证书的颁发和认证都依赖于 CA，并假定 CA 颁发的证书是可靠的、可信赖的，证书里面的内容是真实的、有效的，并可用于客户机和服务器进行安全的可靠的通信加密。
SSL/TLS 证书用来认证服务器和客户机双方的身份，并用于密钥交换时候的非对称加密。密钥交换完毕之后，就可以用这个密钥做通信数据的对称加密了，具体的加密算法是由客户机和服务器互相协商得来。服务器和客户机由于 SSL/TLS 库的不同以及用户的配置不同，双方支持的算法列表不完全相同，当双方做 SSL/TLS 握手的时候，就需要将自己支持的算法列表及优先顺序告知对方，一旦对方按照优先顺序找到了第一个支持的算法，那么协商完成，否则双方协商失败，SSL/TLS 连接断开。
环境说明：

主机名	角色	IP地址
ldapsrv02.contoso.com	openldap server	192.168.49.139
ldapclient.contoso.com	openldap client + CA	192.168.49.136

ldapsrv02是新添加的一台CentOS 6.5，这里直接使用之前的openldap的安装脚本进行安装，里面并未有任何数据，是一个空的域（域名也是contoso.com，为之后做双机同步做准备）。
准备工作：

在两台CentOS上安装openssl.
yum -y install openssl
[iyunv@ldapclient ~]# rpm -qa openssl
openssl-1.0.1e-15.el6.x86_64
[iyunv@ldapsrv02 ~]# rpm -qa openssl
openssl-1.0.1e-15.el6.x86_64
一、建立CA中心
1）配置CA签发信息
cd /etc/pki/CA/
touch index.txt
echo 01 >serial
cp /etc/pki/tls/openssl.cnf /etc/pki/tls/openssl.cnf.bak$(date +%F)
vi /etc/pki/tls/openssl.cnf
[iyunv@ldapclient CA]# diff /etc/pki/tls/openssl.cnf.bak2016-09-18 /etc/pki/tls/openssl.cnf
50c50
< certificate        = $dir/cacert.pem         # The CA certificate
---
> certificate        = $dir/CA.crt            # The CA certificate
55c55
< private_key        = $dir/private/cakey.pem# The private key
---
> private_key        = $dir/private/CA.key   # The private key
130c130
< countryName_default                = XX
---
> countryName_default                = CN
135c135
< #stateOrProvinceName_default        = Default Province
---
> stateOrProvinceName_default        = Guangdong
138c138
< localityName_default        = Default City
---
> localityName_default        = Shenzhen
141c141
< 0.organizationName_default        = Default Company Ltd
---
> 0.organizationName_default        = contoso
148c148
< #organizationalUnitName_default        =
---
> organizationalUnitName_default        = Tech
2）CA服务器生成自己的私钥

[iyunv@ldapclient CA]# (umask 077;openssl genrsa -out private/CA.key)
Generating RSA private key, 1024 bit long modulus
...............++++++
..........++++++
e is 65537 (0x10001)
3）CA服务器生成公钥（CA证书）

[iyunv@ldapclient CA]# openssl req -new -x509 -key private/CA.key >CA.crt
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) [CN]:
State or Province Name (full name) [Guangdong]:
Locality Name (eg, city) [Shenzhen]:
Organization Name (eg, company) [contoso]:
Organizational Unit Name (eg, section) [Tech]:
Common Name (eg, your name or your server's hostname) []:ca.contoso.com
Email Address []:1217406852@qq.com
二、openldap server生成私钥及证书请求文件

1）ldapsrv02生成自己的私钥
[iyunv@ldapsrv02 ~]# openssl genrsa -out ldapsrv02.key
Generating RSA private key, 1024 bit long modulus
...........................++++++
.....++++++
e is 65537 (0x10001)
2）ldapsrv02生成证书请求文件
[iyunv@ldapsrv02 ~]# openssl req -new -key ldapsrv02.key -out ldapsrv02.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) []:Guangdong  
Locality Name (eg, city) [Default City]:Shenzhen
Organization Name (eg, company) [Default Company Ltd]:contoso
Organizational Unit Name (eg, section) []:Tech
Common Name (eg, your name or your server's hostname) []:ldapsrv02.contoso.com
Email Address []:1217406852@qq.com

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:123456
An optional company name []:123456
三、CA服务器向openldap server签发证书
1）ldapsrv02向CA请求证书
[iyunv@ldapsrv02 ~]# scp ldapsrv02.csr root@192.168.49.136:/root
The authenticity of host '192.168.49.136 (192.168.49.136)' can't be established.
RSA key fingerprint is f9:ce:14:5d:cd:bb:3c:b4:0d:0b:fc:21:3a:92:43:6b.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.49.136' (RSA) to the list of known hosts.
root@192.168.49.136's password:
ldapsrv02.csr                                                   100%  777     0.8KB/s   00:00   
2）CA服务器颁发证书

[iyunv@ldapclient CA]# openssl ca -in /root/ldapsrv02.csr -out /root/ldapsrv02.crt
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: Sep 18 08:22:46 2016 GMT
            Not After : Sep 18 08:22:46 2017 GMT
        Subject:
            countryName               = CN
            stateOrProvinceName       = Guangdong
            organizationName          = contoso
            organizationalUnitName    = Tech
            commonName                = ldapsrv02.contoso.com
            emailAddress              = 1217406852@qq.com
        X509v3 extensions:
            X509v3 Basic Constraints:
                CA:FALSE
            Netscape Comment:
                OpenSSL Generated Certificate
            X509v3 Subject Key Identifier:
                39:FB:0E:BD:7D:03:7E:F3:9E:C3:BE:5B:4D:45:8B:63:B7:8B:7F:26
            X509v3 Authority Key Identifier:
                keyid:08:FF:94:52:EC:BD:97:12:5B:96:DD:1E:36:08:43:FF:AD:2F:7B:C8

Certificate is to be certified until Sep 18 08:22:46 2017 GMT (365 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
四、openldap server下载并安装证书

1）ldapsrv02下载证书

[iyunv@ldapclient CA]# scp /root/ldapsrv02.crt root@192.168.49.139:/root
The authenticity of host '192.168.49.139 (192.168.49.139)' can't be established.
RSA key fingerprint is 88:23:68:20:34:ef:8b:5c:28:ef:c1:d5:ea:ef:4f:55.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.49.139' (RSA) to the list of known hosts.
root@192.168.49.139's password:
ldapsrv02.crt                                                   100% 3271     3.2KB/s   00:00     
[iyunv@ldapclient CA]# scp CA.crt ldapsrv02:/etc/openldap/certs/
The authenticity of host 'ldapsrv02 (192.168.49.139)' can't be established.
RSA key fingerprint is 88:23:68:20:34:ef:8b:5c:28:ef:c1:d5:ea:ef:4f:55.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'ldapsrv02' (RSA) to the list of known hosts.
root@ldapsrv02's password:
CA.crt                                                          100% 1078     1.1KB/s   00:00   
2）ldapsrv02安装证书
mv ldapsrv02.crt /etc/openldap/certs/
mv ldapsrv02.key /etc/openldap/certs/
chown -R ldap:ldap /etc/openldap/certs/
vi /etc/openldap/ldap.conf     #编辑ldap.conf文件
[iyunv@ldapsrv02 ~]# tail -3 /etc/openldap/ldap.conf
URI    ldap://ldapsrv02.contoso.com
BASE   dc=contoso,dc=com
TLS_CACERTDIR        /etc/openldap/certs
vi /etc/openldap/slapd.conf
[iyunv@ldapsrv02 ~]# grep TLS /etc/openldap/slapd.conf  #编辑slapd.conf文件，主要是TLS配置
# The next three lines allow use of TLS for encrypting connections using a
TLSCACertificatePath /etc/openldap/certs
TLSCertificateFile /etc/openldap/certs/ldapsrv02.crt
TLSCertificateKeyFile /etc/openldap/certs/ldapsrv02.key
[iyunv@ldapsrv02 ~]# service slapd stop  #关闭slapd服务
Stopping slapd:                                            [  OK  ]
[iyunv@ldapsrv02 ~]# slapd -h "ldap://192.168.49.139/ ldaps://192.168.49.139/"  #重启slapd服务，这里同时监听加密和不加密端口
[iyunv@ldapsrv02 ~]# lsof -i :389    #查看不加密的slapd端口389
COMMAND  PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
slapd   1757 root    7u  IPv4  14100      0t0  TCP *:ldap (LISTEN)
slapd   1757 root    8u  IPv6  14101      0t0  TCP *:ldap (LISTEN)
[iyunv@ldapsrv02 ~]# lsof -i :636    #查看加密的slapd端口636
COMMAND  PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
slapd   1757 root    9u  IPv4  14104      0t0  TCP *:ldaps (LISTEN)
slapd   1757 root   10u  IPv6  14105      0t0  TCP *:ldaps (LISTEN)
[iyunv@ldapsrv02 ~]# netstat -tunlp|grep slapd  #查看slapd监听的端口
tcp        0      0 0.0.0.0:636                 0.0.0.0:*                   LISTEN      1757/slapd         
tcp        0      0 0.0.0.0:389                 0.0.0.0:*                   LISTEN      1757/slapd         
tcp        0      0 :::636                      :::*                        LISTEN      1757/slapd         
tcp        0      0 :::389                      :::*                        LISTEN      1757/slapd
五、ldapclient客户端测试

1）下载CA公钥

cp /etc/pki/CA/private/CA.key  /etc/openldap/certs/
说明：因为我的CA证书中心也同时作为ldap客户端，所以这里只需要拷贝到对应目录即可，如果CA证书中心和ldap客户端不在同一台服务器上，需要使用scp或者rz等其他方式拷贝到ldap客户端上。
2）修改ldap客户端配置

cp /etc/openldap/ldap.conf /etc/openldap/ldap.conf.bak$(date +%F)
vi /etc/openldap/ldap.conf
[iyunv@ldapclient CA]# /etc/init.d/nslcd restart
Stopping nslcd:                                            [  OK  ]
Starting nslcd:                                            [  OK  ]
[iyunv@ldapclient CA]# ldapwhoami -v -x -Z
ldap_initialize( <DEFAULT> )
ldap_start_tls: Can't contact LDAP server (-1)
        additional info: TLS error -8172:Peer's certificate issuer has been marked as not trusted by the user.
ldap_sasl_bind(SIMPLE): Can't contact LDAP server (-1)
上述错误的解决方法是：
        编辑/etc/openldap/ldap.conf，添加““TLS_REQCERT allow”，然后重启nslcd服务即可。
vi /etc/openldap/ldap.conf
[iyunv@ldapclient CA]# egrep -v "#|^$" /etc/openldap/ldap.conf
TLS_REQCERT  allow
TLS_CACERTDIR /etc/openldap/certs
BASE dc=contoso,dc=com
URI ldaps://ldapsrv02.contoso.com/
/etc/init.d/nslcd restart
[iyunv@ldapclient CA]# ldapwhoami -v -x -Z
ldap_initialize( <DEFAULT> )
ldap_start_tls: Operations error (1)
        additional info: TLS already started
anonymous
Result: Success (0)
[iyunv@ldapclient CA]# ldapsearch -x -D "cn=admin,dc=contoso,dc=com" -H ldaps://192.168.49.139 -W -b "dc=contoso,dc=com"
Enter LDAP Password:
# extended LDIF
#
# LDAPv3
# base <dc=contoso,dc=com> with scope subtree
# filter: (objectclass=*)
# requesting: ALL
#

# search result
search: 2
result: 32 No such object

# numResponses: 1
#因为ldapsrv02仅仅是安装了openldap，并没有导入数据，所以这里的查询结果是正确的。