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WarWalking (1)

Published January 6, 2004 by lievenlb


What exactly is a \’WarDriver\’? WarDriver: One who locates and logs
wireless access points while in motion ;[benign]. WarDriving was
invented by Peter Shipley and now commonly practiced by hobbyists,
hackers and security analysts worldwide. More information about this
trend can be found at wardriving.com. Even if you are not into this
sport, the following (innocent) software may be of use to obtain
information about your wireless network. In a next message I\’ll discuss
a few less innocent software tools. Probably the most popular network
scanner for Mac OSX is MacStumbler. It detects nearby wireless networks,
tells you the channels they use, whether they use WEP
(encryption), give their signal (and noise) strength, the name of the
network and if you click on the Details button it gives you
(among other things) the MAC-address. A similar tool is iStumbler. It
gives roughly the same information : SSID (name). MAC-address,
signal/noise, channel and whether it is encrypted. More information is
available from the iStumbler manual. In addition it presents a
signal graph which is useful if you are trying to decide on which
signal you will let your Airport-basestation broadcast. Using
iStumbler i discovered that there was a recurrent noise at
channel 5 every couple of minutes (don\’t ask what it was) but that on
channel 1 the signal was not interrupted.

Both
MacStumbler and iStumbler are active scanners
meaning that they send out probe request to nearby access points. As a
result they are not able to detect closed networks. To detect
them you need far more intrusive passive scanning software, but
that is for next time.

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dinner’s ready

Published January 5, 2004 by lievenlb

Not
all improvements to our home-network need to be high tech. Here is a
very simple measure which reduces the amount of in-house shouting
drastically. Often all of us are online, either to work, surf the net,
MSN-chat or listening to iTunes and clearly we can easily see which
other computers are on at the time. Just click on the Network
icon on the top left of the Finder-window. As our computer-names
are quite descriptive (iMacLieven,iMacBente,eMacAnn,iBookGitte)
it will give a good indication of who is online but as we can all login
to all these computers one can never be too certain. An elegant way to
find out who is on whose computer is to use the Rendezvous window
in iChat. This lists all people on the network which have
iChat running on their computers and then iChat can be used to send
simple messages immediately to a given person (such as : turn that music
down or telephone for you etc.). There is just one problem : as the kids
use MSN to chat they never turn on iChat and as we are of a non-chatting
generation neither do we. Fortunately, it is easy to force iChat to be
running at login.

On each computer go to
SystemPrefrences-Accounts and for each user go to the Startup
Items pane. Click on the + button and browse to the
Applications/iChat program and click Add. Be sure to check
the Hide button and you are done. Next time that person logs in,
iChat will start automatically in the background (the only slightly
annoying thing is a small sound at the end of login) and the user will
appear in any iChat-Rendezvous window.

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graphite ABS can be used

Published January 4, 2004 by lievenlb


I found on the net a way around the problem that a first
generation graphite airport basestation is not compatible with a
third generation extreme ABS. The article is called Extending AirPort’s range with multiple base
stations and addresses precisely my problem (a problem that others
still think is not there judging from the replies to the article). I
checked it out and it works. So, here is the setup that I will use this
summer to get some iBooks in the garden connecting happily to the
internet at the expense of an in-house extra computer running… The
extreme ABS (woonkamer) is configured to run our usual in-house
network. The graphite ABS (terras) will be connected via a
crossed-ethernet cable to an iMac in the dinner room near the garden
window (this iMac is still well within the range of the
woonkamer-network). Here are the System-preferences for the iMac :


Network : Airport : TCP/IP configure using
DHCP ; all others empty
Network : Build-in Ethernet : TCP/IP
configure using DHCP ; all others empty
Sharing : Internet :
Click ‘Start’ for sharing your Airport connection

Here are the configuration parameters of the terras-ABS
:

Internet tab
Connect using:
Ethernet
Configure: Using DHCP
IP address: leave
empty
Subnet mask: leave empty
Router address: leave
empty
DNS servers: leave empty
Domain name: leave
empty
DHCP client ID: leave empty

Network tab
Distribute IP address: CHECKED
Share a single IP address (using DHCP and NAT): CHECKED
DHCP lease: 60 min (default)
Enable AirPort to Ethernet
bridging: CHECKED
all others: leave empty / unchecked

Now any iBook in the garden connecting via Airport to
the terras-network will be able to get on the net.

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