SquidGuard is a URL redirector used to use blacklists with the proxysoftware Squid. There are two big advantages to squidguard: it is fast and it is free.
Linux text utilities
Much of Linux® system administration involves tediously combing through plain-text configuration files. Fortunately, Linux has a rich array of UNIX®-derived data extraction utilities, including head, tail, grep, egrep, fgrep, cut, paste, join, awk, and more. This article uses real-world examples that show how these simple command-line programs can make you a better sysadmin. This article looks at each data extraction utility and its options, applies them to typical files that are used in day-to-day work, and looks at how and why each tool is useful for pulling data from these files.