Apache HTTP Server Version 2.2

Apache > HTTP Server > Documentation > Version 2.2 > SSL/TLS

#### Please note

This document refers to a legacy release (2.2) of Apache httpd. The active release (2.4) is documented here. If you have not already upgraded, please follow this link for more information.

You may follow this link to go to the current version of this document.

# SSL/TLS Strong Encryption: Compatibility

Available Languages: en

This page covers backwards compatibility between mod_ssl and other SSL solutions. mod_ssl is not the only SSL solution for Apache; four additional products are (or were) also available: Ben Laurie's freely available Apache-SSL (from where mod_ssl were originally derived in 1998), Red Hat's commercial Secure Web Server (which was based on mod_ssl), Covalent's commercial Raven SSL Module (also based on mod_ssl) and finally C2Net's (now Red Hat's) commercial product Stronghold (based on a different evolution branch named Sioux up to Stronghold 2.x and based on mod_ssl since Stronghold 3.x).

mod_ssl mostly provides a superset of the functionality of all the other solutions, so it's simple to migrate from one of the older modules to mod_ssl. The configuration directives and environment variable names used by the older SSL solutions vary from those used in mod_ssl; mapping tables are included here to give the equivalents used by mod_ssl.

- Comments

## Configuration Directives

The mapping between configuration directives used by Apache-SSL 1.x and mod_ssl 2.0.x is given in Table 1. The mapping from Sioux 1.x and Stronghold 2.x is only partial because of special functionality in these interfaces which mod_ssl doesn't provide.

### Table 1: Configuration Directive Mapping

Old Directive | mod_ssl Directive | Comment
--- | --- | ---
Apache-SSL 1.x & mod_ssl 2.0.x compatibility:
`SSLEnable` | `SSLEngine on` | compactified
`SSLDisable` | `SSLEngine off` | compactified
`SSLLogFile` file | `-` | Use per-module `LogLevel` setting instead.
`SSLRequiredCiphers` spec | `SSLCipherSuite` spec | renamed
`SSLRequireCipher` c1 ... | `SSLRequire %{SSL_CIPHER} in {"`c1`", ...}` | generalized
`SSLBanCipher` c1 ... | `SSLRequire not (%{SSL_CIPHER} in {"`c1`", ...})` | generalized
`SSLFakeBasicAuth` | `SSLOptions +FakeBasicAuth` | merged
`SSLCacheServerPath` dir | - | functionality removed
`SSLCacheServerPort` integer | - | functionality removed
Apache-SSL 1.x compatibility:
`SSLExportClientCertificates` | `SSLOptions +ExportCertData` | merged
`SSLCacheServerRunDir` dir | - | functionality not supported
Sioux 1.x compatibility:
`SSL_CertFile` file | `SSLCertificateFile` file | renamed
`SSL_KeyFile` file | `SSLCertificateKeyFile` file | renamed
`SSL_CipherSuite` arg | `SSLCipherSuite` arg | renamed
`SSL_X509VerifyDir` arg | `SSLCACertificatePath` arg | renamed
`SSL_Log` file | `-` | Use per-module `LogLevel` setting instead.
`SSL_Connect` flag | `SSLEngine` flag | renamed
`SSL_ClientAuth` arg | `SSLVerifyClient` arg | renamed
`SSL_X509VerifyDepth` arg | `SSLVerifyDepth` arg | renamed
`SSL_FetchKeyPhraseFrom` arg | - | not directly mappable; use SSLPassPhraseDialog
`SSL_SessionDir` dir | - | not directly mappable; use SSLSessionCache
`SSL_Require` expr | - | not directly mappable; use SSLRequire
`SSL_CertFileType` arg | - | functionality not supported
`SSL_KeyFileType` arg | - | functionality not supported
`SSL_X509VerifyPolicy` arg | - | functionality not supported
`SSL_LogX509Attributes` arg | - | functionality not supported
Stronghold 2.x compatibility:
`StrongholdAccelerator` engine | `SSLCryptoDevice` engine | renamed
`StrongholdKey` dir | - | functionality not needed
`StrongholdLicenseFile` dir | - | functionality not needed
`SSLFlag` flag | `SSLEngine` flag | renamed
`SSLSessionLockFile` file | `SSLMutex` file | renamed
`SSLCipherList` spec | `SSLCipherSuite` spec | renamed
`RequireSSL` | `SSLRequireSSL` | renamed
`SSLErrorFile` file | - | functionality not supported
`SSLRoot` dir | - | functionality not supported
`SSL_CertificateLogDir` dir | - | functionality not supported
`AuthCertDir` dir | - | functionality not supported
`SSL_Group` name | - | functionality not supported
`SSLProxyMachineCertPath` dir | `SSLProxyMachineCertificatePath` dir | renamed
`SSLProxyMachineCertFile` file | `SSLProxyMachineCertificateFile` file | renamed
`SSLProxyCipherList` spec | `SSLProxyCipherSpec` spec | renamed

## Environment Variables

The mapping between environment variable names used by the older SSL solutions and the names used by mod_ssl is given in Table 2.

### Table 2: Environment Variable Derivation

Old Variable | mod_ssl Variable | Comment
--- | --- | ---
`SSL_PROTOCOL_VERSION` | `SSL_PROTOCOL` | renamed
`SSLEAY_VERSION` | `SSL_VERSION_LIBRARY` | renamed
`HTTPS_SECRETKEYSIZE` | `SSL_CIPHER_USEKEYSIZE` | renamed
`HTTPS_KEYSIZE` | `SSL_CIPHER_ALGKEYSIZE` | renamed
`HTTPS_CIPHER` | `SSL_CIPHER` | renamed
`HTTPS_EXPORT` | `SSL_CIPHER_EXPORT` | renamed
`SSL_SERVER_KEY_SIZE` | `SSL_CIPHER_ALGKEYSIZE` | renamed
`SSL_SERVER_CERTIFICATE` | `SSL_SERVER_CERT` | renamed
`SSL_SERVER_CERT_START` | `SSL_SERVER_V_START` | renamed
`SSL_SERVER_CERT_END` | `SSL_SERVER_V_END` | renamed
`SSL_SERVER_CERT_SERIAL` | `SSL_SERVER_M_SERIAL` | renamed
`SSL_SERVER_SIGNATURE_ALGORITHM` | `SSL_SERVER_A_SIG` | renamed
`SSL_SERVER_DN` | `SSL_SERVER_S_DN` | renamed
`SSL_SERVER_CN` | `SSL_SERVER_S_DN_CN` | renamed
`SSL_SERVER_EMAIL` | `SSL_SERVER_S_DN_Email` | renamed
`SSL_SERVER_O` | `SSL_SERVER_S_DN_O` | renamed
`SSL_SERVER_OU` | `SSL_SERVER_S_DN_OU` | renamed
`SSL_SERVER_C` | `SSL_SERVER_S_DN_C` | renamed
`SSL_SERVER_SP` | `SSL_SERVER_S_DN_SP` | renamed
`SSL_SERVER_L` | `SSL_SERVER_S_DN_L` | renamed
`SSL_SERVER_IDN` | `SSL_SERVER_I_DN` | renamed
`SSL_SERVER_ICN` | `SSL_SERVER_I_DN_CN` | renamed
`SSL_SERVER_IEMAIL` | `SSL_SERVER_I_DN_Email` | renamed
`SSL_SERVER_IO` | `SSL_SERVER_I_DN_O` | renamed
`SSL_SERVER_IOU` | `SSL_SERVER_I_DN_OU` | renamed
`SSL_SERVER_IC` | `SSL_SERVER_I_DN_C` | renamed
`SSL_SERVER_ISP` | `SSL_SERVER_I_DN_SP` | renamed
`SSL_SERVER_IL` | `SSL_SERVER_I_DN_L` | renamed
`SSL_CLIENT_CERTIFICATE` | `SSL_CLIENT_CERT` | renamed
`SSL_CLIENT_CERT_START` | `SSL_CLIENT_V_START` | renamed
`SSL_CLIENT_CERT_END` | `SSL_CLIENT_V_END` | renamed
`SSL_CLIENT_CERT_SERIAL` | `SSL_CLIENT_M_SERIAL` | renamed
`SSL_CLIENT_SIGNATURE_ALGORITHM` | `SSL_CLIENT_A_SIG` | renamed
`SSL_CLIENT_DN` | `SSL_CLIENT_S_DN` | renamed
`SSL_CLIENT_CN` | `SSL_CLIENT_S_DN_CN` | renamed
`SSL_CLIENT_EMAIL` | `SSL_CLIENT_S_DN_Email` | renamed
`SSL_CLIENT_O` | `SSL_CLIENT_S_DN_O` | renamed
`SSL_CLIENT_OU` | `SSL_CLIENT_S_DN_OU` | renamed
`SSL_CLIENT_C` | `SSL_CLIENT_S_DN_C` | renamed
`SSL_CLIENT_SP` | `SSL_CLIENT_S_DN_SP` | renamed
`SSL_CLIENT_L` | `SSL_CLIENT_S_DN_L` | renamed
`SSL_CLIENT_IDN` | `SSL_CLIENT_I_DN` | renamed
`SSL_CLIENT_ICN` | `SSL_CLIENT_I_DN_CN` | renamed
`SSL_CLIENT_IEMAIL` | `SSL_CLIENT_I_DN_Email` | renamed
`SSL_CLIENT_IO` | `SSL_CLIENT_I_DN_O` | renamed
`SSL_CLIENT_IOU` | `SSL_CLIENT_I_DN_OU` | renamed
`SSL_CLIENT_IC` | `SSL_CLIENT_I_DN_C` | renamed
`SSL_CLIENT_ISP` | `SSL_CLIENT_I_DN_SP` | renamed
`SSL_CLIENT_IL` | `SSL_CLIENT_I_DN_L` | renamed
`SSL_EXPORT` | `SSL_CIPHER_EXPORT` | renamed
`SSL_KEYSIZE` | `SSL_CIPHER_ALGKEYSIZE` | renamed
`SSL_SECKEYSIZE` | `SSL_CIPHER_USEKEYSIZE` | renamed
`SSL_SSLEAY_VERSION` | `SSL_VERSION_LIBRARY` | renamed
`SSL_STRONG_CRYPTO` | `-` | Not supported by mod_ssl
`SSL_SERVER_KEY_EXP` | `-` | Not supported by mod_ssl
`SSL_SERVER_KEY_ALGORITHM` | `-` | Not supported by mod_ssl
`SSL_SERVER_KEY_SIZE` | `-` | Not supported by mod_ssl
`SSL_SERVER_SESSIONDIR` | `-` | Not supported by mod_ssl
`SSL_SERVER_CERTIFICATELOGDIR` | `-` | Not supported by mod_ssl
`SSL_SERVER_CERTFILE` | `-` | Not supported by mod_ssl
`SSL_SERVER_KEYFILE` | `-` | Not supported by mod_ssl
`SSL_SERVER_KEYFILETYPE` | `-` | Not supported by mod_ssl
`SSL_CLIENT_KEY_EXP` | `-` | Not supported by mod_ssl
`SSL_CLIENT_KEY_ALGORITHM` | `-` | Not supported by mod_ssl
`SSL_CLIENT_KEY_SIZE` | `-` | Not supported by mod_ssl

## Custom Log Functions

When mod_ssl is enabled, additional functions exist for the Custom Log Format of `mod_log_config` as documented in the Reference Chapter. Beside the ```%{`varname`}x`'' eXtension format function which can be used to expand any variables provided by any module, an additional Cryptography ```%{`name`}c`'' cryptography format function exists for backward compatibility. The currently implemented function calls are listed in Table 3.

### Table 3: Custom Log Cryptography Function

Function Call | Description
--- | ---
`%...{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` | Certificate Verification Error (numerical)
`%...{errstr}c` | Certificate Verification Error (string)

Available Languages: en

## Comments

Notice:
This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed again by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Freenode, or sent to our mailing lists.