n00bs on Ubuntu posted a guide about installing Gnome Nanny Parental Control on Ubuntu 10.04 LTS

Gnome Nanny is an easy way to control what your kids are doing in the computer. You can limit how much time a day each one of them is browsing the web, chatting or doing email. You can also decide at which times of the day the can do this things. Gnome Nanny filters what web pages are seen by each user, so you can block all undesirable webs and have your kids enjoy the internet with ease of mind, no more worries!

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