my question is about web crawling to find all websites linking to a specific website

I have been given a project to know what websites are linking to some particular website, for example, Wikipedia. We can do this by web crawling, and according to my knowledge web crawler find all the url in a website and then find all the url in that url and so on crawl all the internet. But we are asked to start from any website on the internet and reach the desired website Wikipedia. They say this way we will find all the websites that are linking to the Wikipedia. I am completely confused where to start. please help.