Anonip is a tool to anonymize IP addresses in log files.

It masks the last bits of IPv4 and IPv6 addresses. That way most of the relevant
information is preserved, while the IP-address does not match a particular
individuum anymore.

Depending on your webserver software, the log entries may directly get piped to
Anonip. The unmasked IP addresses will never be written to any file.

Using shell redirects, it's also possible to rewrite existing log files.