Apache Security - Ivan Ristic [52]
Installing mod_ssl
To add SSL to Apache 1, download and unpack the mod_ssl distribution into the same top folder where the existing Apache source code resides. In my case, this is /usr/local/src. I will assume you are using Apache Version 1.3.31 and mod_ssl Version 2.8.19-1.3.31:
$ cd /usr/local/src
$ wget -q http://www.modssl.org/source/mod_ssl-2.8.19-1.3.31.tar.gz
$ tar zxvf mod_ssl-2.8.19-1.3.31.tar.gz
$ cd mod_ssl-2.8.19-1.3.31
$ ./configure --with-apache=../apache_1.3.31
Return to the Apache source directory (cd ../apache_1.3.31) and configure Apache, adding a --enable-module=ssl switch to the configure command. Proceed to compile and install Apache as usual:
$ ./configure --prefix=/usr/local/apache --enable-module=ssl
$ make
# make install
Adding SSL to Apache 2 is easier as you only need to add a --enable-ssl switch to the configure line. Again, recompile and reinstall. I advise you to look at the configuration generated by the installation (in httpd.conf for Apache 1 or ssl.conf for Apache 2) and familiarize yourself with the added configuration options. I will cover these options in the following sections.
Generating Keys
Once SSL is enabled, the server will not start unless a private key and a certificate are properly configured. Private keys are commonly protected with passwords (also known as passphrases) to add additional protection for the keys. But when generating a private key for a web server, you are likely to leave it unprotected because a password-protected private key would require the password to be manually typed every time the web server is started or reconfigured. This sort of protection is not realistic. It is possible to tell Apache to ask an external program for a passphrase (using the SSLPassPhraseDialog directive), and some people use this option to keep the private keys encrypted and avoid manual interventions. This approach is probably slightly more secure but not much. To be used to unlock the private key, the passphrase must be available in cleartext. Someone who is after the private key is likely to be determined enough to continue to look for the passphrase.
The following generates a nonprotected, 1,024-bit server private key using the RSA algorithm (as instructed by the genrsa command) and stores it in server.key:
# cd /usr/local/apache/conf
# mkdir ssl
# cd ssl
# openssl genrsa -out server.key 1024
Generating RSA private key, 1024 bit long modulus
....................................++++++
..........................++++++
e is 65537 (0x10001)
Only the private key was generated:
# cat server.key
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
But the public key can be extracted from the private key:
# openssl rsa -in server.key -pubout
writing RSA key
-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCtLL9Tb27Tg/KWdPbhNXAwQFfJ
8cxkAQW8W9yI5dZMMObpO3kZ4MUep2OmiEGI6gsBSyZ8tSnl3AfD/XFWwCfrcTWQ
i4qwS1sQiGMV+DglPJNKMOfqtR1cqTUIpajqt12Zc57LVhIQJV3Q6Cnpupo5n40a
vwUXzEm5VmUxwzmmWQIDAQAB
-----END PUBLIC KEY-----
Generating a Certificate