Scientific journals charge subscription fees in order to access their content. If you’re an employed scientist, the university or company where you work usually buys an institution-wide subscription to a journal. In that case you don’t have to log in to the journal website because it recognizes your IP address as belonging to a subscribing institution. In fact, you don’t even get an account on the journal website, because it’s impractical to issue an account to every single user at a university, for example.
So what do you do when you have to look up something when you’re away from your office? You use SSH with port forwarding to connect to work, then visit the website using a proxy server on that port. Since you are now browsing through a work computer, you can read the journal. There’s nothing wrong with this, because your employer has already paid for your access that content, but the barrier was simply the impracticality of issuing you an individual account.
So it’s really strange that Nature Publishing Group, which publishes the overrated Nature family of journals, seems to want to discourage this practice. If you visit the site of a Nature journal from a non-subscriber IP address, they set a cookie in your browser that says you are not a subscriber. So even when you turn on your proxy server and revisit the site, it still tells you you’re not a subscriber and can’t access the journal article. Luckily, it is easily remedied by erasing your browser’s cookies. (Easily done, that is, but not easily thought of. Hope this helps someone.)
Why, Nature, why? Why would you do this? Do you have scientists’ best interests at heart and you want to prevent them from working at home? Or do you hope that people are gullible enough to pay twice for the same content?