The essence of the internet is the ability to hyperlink to other sites.

Hyperlinking is not unlawful.

So when a Canadian copyright protection site (Captain Copyright) sought to limit linking to it, especially from sites critical of it,  there was quite a bit of discussion about the nature of linking.

If you do not want someone to access your site, password protect it or insist they accept restrictive terms before entering it. However, anyone can link to any site provided it is not for unlawful means.