Just in case you haven't seen them before, they may appear different than you might expect- the ones I have aren't square but 8-sided stars. I'm only mentioning this in case you're not familiar with them, not trying to be an SA. Bill
I think Bill is talking about an 8 point socket which is a square and another square turned 45 degrees. These are female sockets and can be used on the square shoulder of threading taps, etc.
What Oldmo wants is a male plug socket used to take the plugs out of the side and front of the block.
Internal pipe plug socket
External pipe plug socket
Although an extension will work on certain occasion the pipe plug socket fits a little more closely than the extension. Also it is a good idea to heat up the plug with the blue wrench prior to removing it. They can be a real bear coming out at times especially if something like Indian Head was used on them.