KNMI uses a web analytics program called Piwik to see which of its webpages are visited most, how users arrive at the website and what search terms are used in our search feature.
Like any other website, we collect our visitors’ IP addresses for this purpose. These are then stored in ‘log files’. Log files are kept for 5 days on the webserver so that they can be used by Piwik. They are then kept for another 90 days for security purposes, and they may only be consulted for this reason.
The Ministry of General Affairs has measures in place to limit the traceability of visitors to our website as much as possible. For example, immediately after importing log files into Piwik, the last two octets (groups of eight bits) of each IP address are discarded. This takes place in a temporary memory, before the IP address is stored in Piwik.
We collect the following data in log files:
- IP addresses;
- user agents (browser, operating system);
- search terms used to reach our website via external search engines;
- search terms used in the website’s search feature;
- links used within the website;
- links used to reach our website.
Piwik retrieves this data from the log files on the webserver. These log files are kept in the Piwik database for 31 days, and are then deleted. All that remains is a single, aggregated log file, which provides an annual report on the site’s web traffic.
We never provide personal data to third parties unless we have to do so in order to report a criminal offence.