Floo/head-in-the-fireplace & Hogwarts defenses

[bowlwoman]

No: HPFGUIDX 57583

abigailnus wrote:

>However, this discussion, if I'm not mistaken, started with a 
>question about Hogwarts defenses -if Hogwarts is so impregnable, 
>how is it possible that its Floo fireplaces are connected to the 
>outside world?

I think that LMPP may have discovered this type of "travel" 
or "comminication" when they were students.  Sirius and Lupin are the 
only to have ACTUALLY used this type of comminication that we've seen 
around Hogwarts (Snape may have used the "Floo Calling Card", but he 
didn't physically appear somewhere else).  

If LMPP can figure out how to become Animagi, find secret passages 
out of the castle that to this day not even Filch has found and 
create the Marauders Map which show every person on the grounds, why 
couldn't they figure out how to do this?  

bowlwoman