Configuring HTTP cache

Using cache to access web pages that are opened repeatedly reduces Internet traffic. Downloaded files are saved to the hard drive of the Kerio Control host so that it is not necessary to download them from the web server again later.

The cache can be used either for direct access or for access via the proxy server. For more information refer to Configuring proxy server. Also you can use it for Kerio Control reverse proxy. For more information refer to Configuring the reverse proxy. If you use direct access, the HTTP protocol inspector must be applied to the traffic. In the default configuration of Kerio Control, this condition is met for the HTTP protocol at the default port 80.

Configuring HTTP cache

  1. In the administration interface, go to Proxy Server > HTTP Cache.
  2. Check Enable cache for direct access to web.
  3. If you are using proxy server, check Enable cache on Kerio Control non-transparent proxy server.
  4. If you are using reverse proxy, check Enable cache for Kerio Control reverse proxy.
  5. Click Apply.

Configuring TTL

TTL (Time To Live) means that you can configure a default time of how long the object is kept in the cache for.

  1. On tab HTTP Cache, set HTTP protocol TTL (default value: 1 day). This setting applies to all objects where no extra cache period is specified.
  2. Click URL Specific Settings for objects on specific servers or pages.
  3. In the URL Specific Settings dialog, click Add.
  4. In the Add URL dialog, specify URL (or its part) of objects on which the rule will apply. The cache time is specified in hours. Value 0 means that the object will not be kept in the cache.

Cache status and administration

Kerio Control allows monitoring of the HTTP cache usage as well as removal of its contents.

At the bottom of the HTTP Cache tab, basic status information is provided such as the current cache size occupied and efficiency of the cache. The efficiency status stands for number of objects kept in the cache in proportion to the total number of queries (since the startup of the Kerio Control). The efficiency of the cache depends especially on user behavior and habits (if users visit certain web pages regularly, if any websites are accessed by multiple users, etc.) and, in a manner, it can be also affected by the configuration parameters described above. If the efficiency of the cache is permanently low (less than 5 percent), change the cache configuration.

The Clear cache button deletes all objects saved in cache.