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4. Configuring your Apache Server

The Apache server must be configured with supplementary API modules in order to support SSL. There are many SSL software packages available. My examples are based on Apache configured with ModSSL and OpenSSL. There are countless mailing lists and newsgroups available to support these products. You may find these instructions helpful for some commercial SSL software packages that are based on the Apache web server.

A few things to keep in mind: You can have multiple virtual hosts on the same server. You can have numerous name-based virtual hosts on the same IP address. You can also have numerous name-based virtual hosts and one (1) secure virtual host on the same IP. But - you cannot have multiple secure virtual hosts on the same IP. The question that so many ask: Why? The answer is: SSL works below the application layer. Name based hosts are not defined until the application layer.

Specifically, you cannot have multiple secure virtual hosts on the same SOCKET (IP address + port). By default, a secure host will use port 443. You can change configure your virtual host to use a different port number with the same IP, thus creating another socket. There are many disadvantages to this approach. The most obvious disadvantage is that if you are not using the default port, your URL must also contain the port number to access the secure site.

Example:

Another disadvantage is that if you introduce more ports, you will be providing more opportunities for port sniffing hackers. Last, if you select a port that is used by something else, you will create conflict problem.

4.1 Define a Secure Virtual Host

Setting up virtual hosts is fairly straightforward. I will go through the basics of setting up a secure virtual host.

In these examples, I use the .crt and .key file extensions. That is my personal way of avoiding confusion with the various files. With Apache, you can use any extension you choose - or no extension at all.

All of your secure virtual hosts should be contained within <IfDefine SSL> and </IfDefine SSL>, usually located towards the end of the httpd.conf file.

An example of a secure virtual host:

<VirtualHost 172.18.116.42:443>
DocumentRoot /etc/httpd/htdocs
ServerName www.somewhere.com
ServerAdmin someone@somewhere.com
ErrorLog /etc/httpd/logs/error_log
TransferLog /etc/httpd/logs/access_log
SSLEngine on
SSLCertificateFile /etc/httpd/conf/ssl.crt/server.crt
SSLCertificateKeyFile /etc/httpd/conf/ssl.key/server.key
SSLCACertificateFile /etc/httpd/conf/ssl.crt/ca-bundle.crt
<Files ~ "\.(cgi|shtml)$">
      SSLOptions +StdEnvVars
</Files>
<Directory "/etc/httpd/cgi-bin">
      SSLOptions +StdEnvVars
</Directory>
SetEnvIf User-Agent ".*MSIE.*" nokeepalive ssl-unclean-shutdown
CustomLog /etc/httpd/logs/ssl_request_log \
          "%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x \"%r\" %b"
</VirtualHost>

The directives that are the most important for SSL are the SSLEngine on, SSLCertificateFile, SSLCertificateKeyFile, and in many cases SSLCACertificateFile directives.

SSL Engine

"SSLEngine on" - this is ModSSL's command to start SSL.

SSLCertificateFile

SSLCertificateFile Tells Apache where to find the certificate file and what it is named. The example above shows "server.crt" as the certificate file name. This is the default that is added when you configure ModSSL with Apache. I personally don't recommend using the default names. Save yourself some frustration and name your certificates as servername.crt (domainname.crt). You may also decide to use an alternative directory than the default /etc/httpd/conf/ssl.crt or /usr/local/apache/conf/ssl.crt. Just remember to make the necessary changes to the path.

SSLCertificateKeyFile

SSLCertificateKeyFile tells Apache the name of the private key and where to find it. The directory defined here should have read/write permissions for root only. No one else should have access to this directory.

SSLCACertificateFile

The SSLCACertificateFile directive tells Apache where to find the Intermediate (root) certificate. This directive may or may not be necessary depending on the CA that you are using. This certificate is essentially a ring of trust.

Intermediate Certificate - A Certificate Authority obtains a certificate in much the same way as you. This is known as an intermediate certificate. It basically says that the holder of the intermediate certificate is whom they say they are and is authorized to issue certificates to customers. Web browsers have a list of "trusted" certificate authorities that is updated with each release. If a Certificate authority is fairly new, its intermediate certificate may not be in the browser's list of trusted CA's. Combine this with the fact that most people don't update their browsers very often; it could take years before a CA is recognized as trusted automatically. The solution is to install the intermediate certificate on the server using the SSLCACertificateFile directive. Usually, a "trusted" CA issues the intermediate certificate. If it is not, then you may need to use the SSLCertificateChainFile directive, although this is unlikely.

4.2 Certificate Examples

Server Certificate File

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

Contents of the Certificate File

Certificate:
   Data:
     Version: 3 (0x2)
     Serial Number: 1516 (0x5ec)
     Signature Algorithm: md5WithRSAEncryption
     Issuer: C=US, O=Equifax Secure Inc, CN=Equifax Secure E-Business CA
     Validity
       Not Before: Jul 12 15:21:01 2000 GMT
       Not After : Jun  2 22:42:34 2001 GMT
     Subject: C=us, ST=ga, L=atlanta, O=Equifax, OU=Rick, CN=172.18.116.44/Email=richard.sigle@equifax.com
     Subject Public Key Info:
       Public Key Algorithm: rsaEncryption
       RSA Public Key: (1024 bit)
           Modulus (1024 bit):
             00:c8:eb:93:26:97:ca:00:ce:4c:e4:f3:fd:43:31:
             cd:53:ed:b4:8a:ad:93:84:dc:7a:48:39:b5:28:57:
             03:7f:a9:ac:3e:58:6a:7a:e3:52:3e:1e:52:58:a2:
             6f:23:ad:bb:84:d8:88:ed:6d:a5:da:08:6b:c8:6c:
             a5:4c:34:67:d8:46:1c:ca:20:50:b0:e8:54:7f:ca:
             5e:ef:09:ff:6e:8d:a6:2b:02:f5:54:0f:c2:d0:45:
             12:ad:66:e7:8b:dd:68:be:64:a4:9b:69:bd:a4:1a:
             5e:ef:09:ff:6e:8d:a6:2b:02:f5:54:0f:c2:d0:45:
             12:ad:66:e7:8b:dd:68:be:64:a4:9b:69:bd:a4:1a:
             5a:2f:3b:6e:73:84:d8:d6:17:bd:12:39:34:fa:3d:
             d8:a9:e8:59:3c:c2:61:c5:b3
           Exponent: 65537 (0x10001)
     X509v3 extensions:
       X509v3 Key Usage: critical
          Digital Signature, Non Repudiation, Key Encipherment, Data Encipherment
       Netscape Cert Type:
          SSL Server
       X509v3 Authority Key Identifier:
          keyid:5B:E0:A8:75:1C:78:02:47:71:AB:CE:27:32:E7:24:88:42:28:48:56
   Signature Algorithm: md5WithRSAEncryption
     87:53:74:e9:e1:a6:10:56:8c:fa:63:0e:7b:72:ff:76:4b:79:
     0e:49:2a:58:ed:71:7a:bf:77:61:fa:e8:74:04:37:8c:d3:6a:
     9a:3d:80:76:7a:c3:64:30:e7:1b:40:25:4e:2a:81:8b:e5:ac:
     76:a4:38:67:cc:3f:93:43:e1:1d:c3:8d:ba:ed:cc:d7:aa:a4:
     ab:d3:84:77:7c:8f:26:f6:dd:ba:3b:6a:99:81:e1:9e:7e:0f:
     ca:a6:ff:c0:c3:59:6e:dc:a6:03:23:bf:8f:24:ff:15:ad:ac:
     0d:85:fc:38:bf:d1:24:2d:1a:d3:72:55:12:95:5f:65:f0:60:
     df:b1

Private Key File

-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC,124F61450D85A480
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-----END RSA PRIVATE KEY-----

Contents of the Private Key

read RSA key
Enter PEM pass phrase:
Private-Key: (1024 bit)
modulus:
    00:c8:eb:93:26:97:ca:00:ce:4c:e4:f3:fd:43:31:
    cd:53:ed:b4:8a:ad:93:84:dc:7a:48:39:b5:28:57:
    03:7f:a9:ac:3e:58:6a:7a:e3:52:3e:1e:52:58:a2:
    6f:23:ad:bb:84:d8:88:ed:6d:a5:da:08:6b:c8:6c:
    a5:4c:34:67:d8:46:1c:ca:20:50:b0:e8:54:7f:ca:
    5e:ef:09:ff:6e:8d:a6:2b:02:f5:54:0f:c2:d0:45:
    12:ad:66:e7:8b:dd:68:be:64:a4:9b:69:bd:a4:1a:
    5a:2f:3b:6e:73:84:d8:d6:17:bd:12:39:34:fa:3d:
    d8:a9:e8:59:3c:c2:61:c5:b3
publicExponent: 65537 (0x10001)
privateExponent:
    00:b6:57:7d:3b:58:24:1e:a9:1b:85:e9:9c:9e:5f:
    d3:3d:69:0c:21:93:37:bf:2b:2c:da:e1:6c:74:48:
    cb:c7:0f:60:5f:50:74:8a:44:45:be:54:5c:5d:4e:
    45:58:f6:f1:a8:b5:af:46:f2:ec:c2:bc:43:bd:28:
    44:b7:ad:13:d3:ca:de:59:24:e8:fa:f8:e5:5f:45:
    38:2c:a0:a3:de:98:13:d8:80:38:e1:47:53:4c:ea:
    e4:66:c3:82:93:89:c3:90:83:44:e1:13:4f:74:76:
    e2:c0:89:97:77:5f:33:d8:7d:27:21:52:55:c2:d7:
    dc:01:f9:bc:21:8d:a3:f5:c1
prime1:
    00:e3:2d:6b:5e:05:6b:e1:46:e6:ab:ae:f3:8b:d0:
    5f:94:5c:6f:f5:47:46:1d:4e:66:d3:7e:98:18:e0:
    2c:0d:08:ca:b7:29:72:af:53:62:30:ec:be:26:1f:
    cc:5a:ed:65:62:65:70:1e:18:19:61:e3:77:00:a7:
    3a:9e:4e:12:93
prime2:
    00:e2:69:56:78:e8:39:ff:17:db:cc:39:d7:7f:70:
    41:dc:c5:59:43:16:c1:84:4c:ae:e7:5d:8a:c5:4b:
    da:88:8e:03:99:7c:88:f2:8a:13:31:57:44:e0:b5:
    c8:0a:60:b0:05:de:f6:9e:f2:00:ec:37:21:8d:3b:
    dc:8e:c9:d4:61
exponent1:
    1a:ad:6a:be:4f:c4:ab:5f:b8:16:d1:24:a8:76:7f:
    c2:dc:58:09:65:a5:46:2b:be:c7:77:46:45:25:8e:
    06:b9:d1:94:50:b9:b6:fd:03:ba:db:12:39:47:e2:
    a7:8a:d9:2d:04:dc:75:ac:3e:ce:cf:f7:59:8c:49:
    c5:ed:45:21
exponent2:
    2d:4e:fd:32:06:ef:0c:40:7f:08:d8:8e:6a:7f:51:
    7e:d7:b3:6c:3c:92:8f:62:35:22:31:d3:02:76:92:
    8d:ff:35:73:32:bb:c9:25:9e:7f:a2:42:33:61:cd:
    5d:5e:49:fb:72:ca:11:b6:c6:3e:7f:2d:e4:b0:95:
    0b:b2:12:21
coefficient:
    50:52:09:22:cb:fb:b2:b8:58:85:ab:1d:82:b9:6e:
    d0:f6:dc:e8:ce:a6:5d:a1:ff:c8:4d:3b:2b:1c:19:
    64:f0:c4:4a:bc:b2:1d:2b:2d:09:59:83:a3:9a:89:
    f8:db:2c:2c:8a:bd:fd:a3:16:51:76:aa:ce:ea:85:
    6b:1c:9f:f7

4.3 Restart the Web Server

The script to restart the webserver may be located in /usr/local/sbin, /usr/sbin, (where the script is called httpd) or /usr/local/apache/bin (where the script is called apachectl). If you are not running the server with SSL enabled, you will need to stop and start the server. You may also write your own customized scripts to start, restart, and stop your server. As long as it starts the SSL engine, you should be OK.

The commands are:

httpd stop
httpd startssl
httpd restart

or

apachectl stop
apachectl startssl
apachectl restart


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