What is the meaning of '@' in the URL?

Question

Let us try to access

http://yahoo.com@3627729518 

with any browser. We get redirected to google.com.

3627729518 is the decimal representation of 11011000.00111010.11000010 .01101110 without dots. What's the reason of such behavior?

Note: I've changed the url so it's universal, but still, there is http://domain@ip. Originally it was local bank url and a scam-service's ip.

Answer 1

It's a malicious url, abusing the http://username:password@hostname support to make it LOOK like a yahoo url.

But it's actually taking you to that IP address (yes, an IP address is just a number, and can be represented by an integer). So that url is effectively:

http://[email protected] 

which reverse DNSs to

http://[email protected] 

so probably a Google Fibre customer in Dallas/Fort Worth.

Answer 2

It's a very old type of URL format still supported by some browsers.

@ was used in specifying a user name and password sent via Basic Authentication to the web site on the right hand site of the @. For example;

http://username:[email protected] 

would have sent the username of username, and the password of (you've guessed it) password to example.com. This meant if you created that as a bookmark you wouldn't have to login, it'd be sent for you. Not the most secure idea.