mod_ssl Chapter 4
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Compatibility

H ere we talk about backward compatibility to other SSL solutions. As you perhaps know mod_ssl is not the only existing SSL solution for Apache. Actually there are four additional products available: Ben Laurie's freely available Apache-SSL (from where mod_ssl were originally derived), RedHat's commercial Secure Web Server (which is based on mod_ssl), Covalent's commercial Raven SSL Module (also based on Apache-SSL) and finally C2Net's commercial product Stronghold (based on a different evolution branch named Sioux).   
Table Of Contents
        Configuration Directives
        Environment Variables
        Custom Log Functions

The idea in mod_ssl is mainly the following: because mod_ssl provides mostly a superset of the functionality of all other solutions we can easily provide backward compatibility for most of the cases. Actually there are three compatibility areas we currently address: configuration directives, environment variables and custom log functions.

Configuration Directives

For backward compatibility to the configuration directives of other SSL solutions we do an on-the-fly mapping: directives which have a direct counterpart in mod_ssl are mapped silently while other directives lead to a warning message in the logfiles. The currently implemented directive mapping is listed in Table 1.

Table 1: Configuration Directive Mapping
Old Directive mod_ssl Directive Comment
Apache-SSLSSLEnableSSLEngine oncompactified
Apache-SSLSSLDisableSSLEngine offcompactified
Apache-SSLSSLCacheServerPath dir-functionality removed
Apache-SSLSSLCacheServerPort integer-functionality removed
Apache-SSLSSLRequiredCiphers argSSLCipherList argrenamed
SiouxSSL_CertFile fileSSLCertificateFile filerenamed
SiouxSSL_KeyFile fileSSLCertificateKeyFile filerenamed
SiouxSSL_CertFileType arg-functionality not supported
SiouxSSL_KeyFileType arg-functionality not supported
SiouxSSL_CipherSuite argSSLCipherList argrenamed
SiouxSSL_FetchKeyPhraseFrom arg-not directly mappable
SiouxSSL_X509VerifyDir argSSLCACertificatePath argrenamed
SiouxSSL_X509VerifyPolicy arg-functionality not supported
SiouxSSL_Log fileSSLLogFile filerenamed
SiouxSSL_LogX509Attributes arg-functionality not supported
SiouxSSL_SessionDir dirSSLSessionCacheStorage dir/ssl_scacherenamed
SiouxSSL_Connect flagSSLEngine flagrenamed
SiouxSSL_ClientAuth argSSLVerifyClient argrenamed
SiouxSSL_X509VerifyDepth argSSLVerifyDepth argrenamed


Environment Variables

...


Custom Log Functions

%...{version}c:    SSL protocol version
%...{cipher}c:     SSL cipher
%...{subjectdn}c:  Client Certificate subject distinguished name
%...{issuerdn}c:   Client Certificate issuer  distinguished name
%...{errcode}c:    X509 verify error code
%...{errstr}c:     X509 verify error string
Use these with the CustomLog directive to create a custom SSL logfile:


Variable Name: Description:
%...{version}c SSL protocol version
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mod_ssl 2.1, User Manual
The Apache Interface to SSLeay
Copyright © 1998 Ralf S. Engelschall
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