The Webalizer - A log file analysis program -- DNS information
The webalizer has the ability to perform reverse DNS lookups, and
fully supports both IPv4 and IPv6 addressing schemes. This document
attempts to explain how it works, and some things that you should be
aware of when using the DNS lookup features.
Note: The Reverse DNS feature may be enabled or disabled at compile
time. DNS lookup code is enabled by default. You can run The
Webalizer using the '-vV' command line options to determine what
options are enabled in the version you are using.
DNS lookups are made against a DNS cache file containing IP addresses
and resolved names. If the IP address is not found in the cache file,
it will be left as an IP address. In order for this to happen, a
cache file MUST be specified when the Webalizer is run, either using
the '-D' command line switch, or a "DNSCache" configuration file
keyword. If no cache file is specified, no attempts to perform DNS
lookups will be done. The cache file can be made three different ways.
1) You can have the Webalizer pre-process the specified log file at
run-time, creating the cache file before processing the log file
normally. This is done by setting the number of DNS Children
processes to run, either by using the '-N' command line switch or
the "DNSChildren" configuration keyword. This will cause the
Webalizer to spawn the specified number of processes which will
be used to do reverse DNS lookups.. generally, a larger number
of processes will result in faster resolution of the log, however
if set too high may cause overall system degradation. A setting
of between 5 and 20 should be acceptable, and there is a maximum
limit of 100. If used, a cache filename MUST be specified also,
using either the '-D' command line switch, or the "DNSCache"
configuration keyword. Using this method, normal processing will
continue only after all IP addresses have been processed, and the
cache file is created/updated.
2) You can pre-process the log file as a standalone process, creating
the cache file that will be used later by the Webalizer. This is
done by running the Webalizer with a name of 'webazolver' (ie: the