How to wake up a computer remotly

[Aaron Grewell]

> > 
> >>I mean I'm on coputer A, and want to turn on a computer B (which is 
> >>turned off of course), do some work on it (VNC, telnet, etc...) and then

> >>turning it off.
> >>
> >>Both computer are on a LAN.
> >>
> >>Any hint would be very appreciated.

As has been mentioned, Wake On LAN is the most common way to do this.
The implementations I've seen are broadcast-based, so the machine
sending the WOL "magic packet" must be on the same subnet as the machine
to be awakened, or else a WOL proxy or routing helper (a la dhcp) must
be used.  The machine sending the magic packet uses the broadcast
address to send, and if the machine at the far end recognizes its MAC
address in the magic packet it wakes up.  In addition to the broadcast
issue, you have to have WOL turned on in BIOS, and if the NIC is not
on-board there may be a special WOL cable to the motherboard.  You'll
also have to make sure the user hasn't turned the machine off at the
power strip or all is for naught.  Not that they would ever do that...