Fireplaces

[delwynmarch]

No: HPFGUIDX 110915

I, Del, wrote :
"Well no, because all the fires the students can have access to would
obviously be monitored. DD would immediately be informed of any
student travelling by Floo powder and of their destination."

Susana replied : 
" I don't think fireplaces work that way - it's more then just monitoring.
 
If they did, anyone could barge in on someone's home uninvited.
Fireplaces must have spells preventing that, the same way you can't
send an owl to someone in hiding and follow it (JKR's explanation was:
wizards can make themselves unreachable if they want)."

Del replies :
My idea and yours are not necessarily mutually exclusive. Just like a
door can be permanently closed, permanently open, openable by anyone
who wants, or guarded, a fireplace could have different kinds of
protection put on it.

 
Susana wrote :
" for someone to get into someone's privet home, there should be an
invitation from someone inside the house."

Del replies :
What about when Amos Diggory called on Arthur Weasley one morning ?
And more importantly, what about when Sirius popped his head in the
Gryffindor fireplace in GoF : there most definitely wasn't any
invitation in this case, and I doubt Sirius would know any required
password.

We probably need more information, I'm not sure we can reach
satisfying explanations with what we've got.

Del