Apache: The Definitive Guide, 3rd Edition

Environment variables

This module provides a lot of SSL information as additional environment variables to the SSI and CGI namespace. The generated variables are listed in Table 11-2. For backward compatibility the information can be made available under different names, too.

Table 11-2. Apache v2 environment variables

Variable	Value type	Description
HTTPS	flag	HTTPS being used
SSL_PROTOCOL	string	The SSL protocol version (SSL v2, SSL v3, TLS v1)
SSL_SESSION_ID	string	The hex-encoded SSL session ID
SSL_CIPHER	string	The cipher specification name
SSL_CIPHER_EXPORT	string	True if cipher is an export cipher
SSL_CIPHER_USEKEYSIZE	number	Number of cipher bits actually used
SLL_CIPHER_ALGKEYSIZE	number	Number of cipher bits possible
SSL_VERSION_INTERFACE	string	The mod_ssl program version
SSL_VERSION_LIBRARY	string	The OpenSSL program version
SSL_CLIENT_M_VERSION	string	The version of the client certificate
SSL_CLIENT_M_SERIAL	string	The serial of the client certificate
SSL_CLIENT_S_DN	string	Subject DN in client’s certificate
SSL_CLIENT_S_DN_ x509	string	Component of client’s Subject DN, where x509 is a component of an X509 DN
SSL_CLIENT_I_DN	string	Issuer DN of a client’s certificate
SSL_CLIENT_I_DN_ x509	string	Component of client’s Issuer DN, where x509 is a component of an X509 DN
SSL_CLIENT_V_START	string	Validity of client’s certificate (start time)
SSL_CLIENT_V_END	string	Validity of client’s ...