Browser redirect tool?

I need to create a tool that sits in Windows in the background and everytime a certain web page is entered, e.g. www.google.com, the tool should automatically redirect to another site.

(Not intended to be a virus, I promise. There is actually a genuine need for this for a client.)

Is this feasible? I know there are lots of viruses/spyware that do this so it should be quite simple t开发者_运维技巧o implement?

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Modify the hosts file.