(This article assumes you’ve heard of IP Address and URL before.)

 

  • When you put the @ symbol in an URL, the letters before it are irrelevant to the site you are going to. (Exceptions: #, ?, /, and \ can’t precede @)

Ex: http://!,.;'[]<>:"{}$%^&*()@goo.gl is a valid website pointing to Google.

  • The real use of the @ symbol in URLs is for authentication when going to a password protected site and making the login process automatic.

Ex: http://username:password@www.topsecretwebsite.com/secretsecret/danger.htm

``- If the page doesn’t need authentication, then the username and password are simply ignored. That means when you look at the beginning of a URL, it may be misleading..

Ex: https://www.whitehouse.gov%as%ohi%bjk%hcf%bmh%cht%nbmj%45@simplyadvanced.net points to our home page

  • And instead of just having @simplyadvanced.net at the end of the URL, it can be obscured by using a numeric IP address instead (i.e. 74.125.67.106, which points to google.com).

Ex: www.pretendwebsitethatdoesntexist.com%123@74.125.67.106

More Ways to Obscure URLs

Once you know how URLs are obfuscated, you’ll be able to protect yourself better online.

Numeric IP addresses can be expressed in a few different ways besides the usual W.X.Y.Z, where each variable is a number between 0 and 255 (Assuming IPv4).

Dword Format

Let’s say we have an IP address, 74.125.67.106, and want to change it into a dword. You’ll want to grab a calculator (use Chrome’s Omnibox) and type in the following:

(((74 * 256) + 125) * 256 + 67) * 256 + 106

You get http://1249723242. Now try to visit that website. Or http://1161805067 for Facebook

Octal Format

I will continue using one of Google’s IP addresses (74.125.67.106) as the example. In Octal format, 74.125.67.106 would be http://112.0175.0103.0152

 

The octal numbers must begin with a 0 (zero) to signify to the computer it is an octal number. And there can be as many leading zeros for as you want.
Ex: 00112.00000000000175.0103.0000000000152

Ways to convert regular IP addresses to octal (base 8 ):

  • Search Google for “how to convert decimal to octal”
  • Use Windows 7′s default calculator in View->Programmer Mode. Type in a number, then click “Oct” on the left-hand side
  • Check out this table: http://www.ascii.cl/conversion.htm

Hexadecimal Format

In hexadecimal format, 74.125.67.106 would become http://0x4A.0x7D.0×43.0x6A

The hexadecimal numbers must begin with a 0x (zero ex) to tell the computer it has to read a hexadecimal number. And all of the dots and 0x can be removed except for the first for a still-valid address. Ex: 0x4A7D436A

Ways to convert regular IP addresses to hexadecimal (base 16):

  • Search Google for “how to convert decimal to hexadecimal”
  • Use Windows’s Calculator in View->Programmer Mode. Type in a number, then click “Hex” on the left side
  • At a quick glance: http://www.ascii.cl/conversion.htm

Combined Format

Try out 74.0175.0×43.0000000000152. Combinations of decimal, octal, and hexadecimal work also! And don’t forget you can also add authentication text before the URL also. Ex: www.notgoingtothissite.com@74.0175.0×43.0000000000152

 

Extra Knowledge

You can find a website’s IP address in Window’s command prompt by using the command ping <url>. Or you can also try nslookup <url>.

Not all websites can be accessed by specific IP addresses. Many sites, like this one, are hosted on a virtual server where multiple (unrelated) websites share an address.

The current protocol of IP addresses is defined as IPv4. This version allows 2^32 (=4,294,967,296) unique numerical addresses. The next generation of addresses, IPv6, will allow 2^128 (about 340 undecillion or 3.4 * 10^38) addresses.