View cipher specifications

This section describes viewing cipher specifications for secure transactions and for a specific HTTP request.

 

Overview

To see which cipher specifications the server uses for secure transactions or for a specific HTTP request, complete one of the following steps.

 

Procedure

1. To see which cipher specifications the server uses for secure transactions. Specify LogLevel info in the configuration file to include informational messages in the error log using the LogLevel directive. The error log is specified by the ErrorLog directive in the http configuration file. The location is set by the ErrorLog directive, which can be configured. Look in the error log for messages in this format: TimeStamp info_message mod_ibm_ssl: Using V2/3 Cipher:longname|shortname. The order that the cipher specifications are displayed in the error log from top to bottom represents the attempted order of the cipher specifications.

2. To see which cipher specification was negotiated with a specific client for a specific request. Change the LogFormat directive to include the cipher specification as part of the information logged for each request.  The format string %{HTTPS_CIPHER}e will log the name of the cipher (for example, "TLS_RSA_WITH_AES_256_CBC_SHA").  Be sure that the LogFormat directive we change is for the format used on the CustomLog directive. Here is an example:

         LogFormat "%h %l %u %t \"%r\" %>s %b %{HTTPS_CIPHER}e" common 
         CustomLog logs/access_log common 
   
   
   

   Look in the access log to find the cipher used.  The position of the cipher will depend on where the %{HTTPS_CIPHER}e format string was placed in the LogFormat directive.  Following are some example access_log entries, using the example LogFormat directive above:

         9.48.108.152 - - [17/Feb/2005:15:37:39 -0500] "GET / HTTP/1.1" 200 1507 SSL_RSA_WITH_RC4_128_SHA 
         9.48.108.152 - - [17/Feb/2005:15:37:40 -0500] "GET /httpTech.view1.gif HTTP/1.1" 200 1814 SSL_RSA_WITH_RC4_128_SHA 
         9.48.108.152 - - [17/Feb/2005:15:37:40 -0500] "GET /httpTech.masthead.gif HTTP/1.1" 200 11844 SSL_RSA_WITH_RC4_128_SHA 
         9.48.108.152 - - [17/Feb/2005:15:37:41 -0500] "GET /httpTech.visit1.gif HTTP/1.1" 200 1457 SSL_RSA_WITH_RC4_128_SHA 
   
   
   

        

   For non-secure requests, "-" will be logged for the cipher specification. We can log other SSL environment variables in the same manner as HTTPS_CIPHER.

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Related concepts

Secure Sockets Layer environment variables