[X4U] Re: Remote access to sleeping machine

[Stroller]

On Jul 26, 2005, at 9:56 pm, Ed Graf wrote:

>> You need the machine's Mac address to utilise it. This won't go 
>> through
>> a router, but the OP doesn't discuss the machine's Internet
>> configuration, so it's impossible to determine whether it is possible
>> to wake the machine from the 'net (I think that with  some cable modem
>> connections it might be possible for packets to traverse the local 
>> loop
>> at that level??).
>
> You likely lost me.
>
> Are you talking about WakeOnLAN or just with any cable modem, or, 
> something else?

Wake-On-LAN (WOL) is the generic name for waking a sleeping machine 
across the network - as far as I am aware the technology is 
cross-platform. If using a Linux box to wake another machine you use a 
program called `ether-wake` and simply run it with the target's MAC 
address as parameter; I am sure there is something similar for the Mac, 
perhaps built into Apple's Remote Desktop.

The MAC address is the hardware address of the machine's network card - 
it is used below the TCP/IP layer on all ethernet networks, and one is 
issued uniquely to all network cards, whether they be PC, Apple or in 
the 802.11g interface of my mobile-phone / PDA. MAC addresses are 
typically used by network hubs & switches to identify the devices 
connected to them, but because they are below the TCP/IP layer they 
cannot be used for addressing beyond a router - routers operate on the 
TCP/IP layer.

MAC addressing is used by some cable internet companies. The UK 
provider NTL binds the cable-modem to the MAC address of the customer's 
computer, to which it is connected by Ethernet cable. I have dealt with 
this service only on one occasion, so I'm unclear of the details or as 
to what happens upstream of the cable modem.

>> Of course, this isn't a relevant issue when the computer is awake, and
>> how would the user know if someone "somehow log[ed] onto and somehow
>> invade[d] his computer", but let's not let a little ignorance get in
>> the way of paranoia.
>
> I admit to quite a bit of ignorance, here, but, what are you talking 
> about, please?

If someone can send a Wake-on-LAN signal to your friend's computer then 
they can probably send any other kind of packet to his computer - my 
router records and drops many connection attempts each day. Your friend 
does not ask "could someone log into and invade my computer when it 
awake", but that should surely be as much a concern. Most connection 
attempts, hacks, "invasions" and even viruses are invisible to the 
casual user, so worrying about whether the machine can be woken from 
sleep is irrelevant - at least that would be obvious!

Paranoia is the best tool of the system administrator, allowing all 
security contingencies to be considered, however it is useless when 
applied with ignorance. Macintosh users who spend money on unnecessary 
anti-virus software are amongst those I would consider inappropriately 
paranoid (as are many PC owners for various behaviours too diverse to 
discuss here).

> BTW, what is an "OP"?

Original Poster (of a discussion thread).

Stroller.