Access log
The cache.log file is important for debugging if Squid is misbehaving. But the most important log file is the access.log file, where Squid logs the live information about who is accessing our proxy server, and related information about the status of requests and replies. The location of the access.log file is determined by the directive access_log, in the Squid configuration file. By default it is set defaults to ${prefix}/var/logs/access.log.
Understanding the access log
The log messages in the access.log file are not as readable as messages in the cache.log file, but once we understand what the different fields mean, it's very easy to interpret the log messages. There are multiple formats in which messages are logged in the access.log file. The messages that we are going to see next, are in the default log format called squid.
