Wednesday, August 30th, 2006

Go get Wifi ... and shorn

As we saw in a previous post, the Palm is ideal for the wardriving or warwalking (find open wifi wireless networking, to connect "borrowed"). However, while most open networks (ie, not requiring user name and password) are because they have been left so intentionally, or because he has installed the most basic known about the wifi network security, there are also times that the cause lies elsewhere, and the person behind this network knows what he does. And really might know what he does.

Is the case with this clever (not to call it that) which has decided to laugh a little of his neighbors, who are using your wireless network to surf the Internet. The process is simple but effective:

  • First divide your network "two", by configuring the DHCP server for that of their teams (whose MAC address known) an IP of the "good part", and all others of the "bad part".

/ etc / dhcpd.conf


ddns-updates off;
ddns-update-style interim;
authoritative;

shared-network local (
subnet *.*.*.* netmask 255.255.255.0 (
range *.*.*.* *.*.*.*;
option routers *.*.*.*;
option subnet-mask 255.255.255.0;
option domain-name "XXXXX";
option domain-name-servers *.*.*.*;
deny unknown-clients;

trusted1 host (
hardware ethernet *:*:*:*:*:*;
fixed-address *.*.*.*;
)
)
subnet 192.168.0.0 netmask 255.255.255.0 (
range 192.168.0.2 192.168.0.10;
option routers 192.168.0.1;
option subnet-mask 255.255.255.0;
option domain-name-servers 192.168.0.1;
allow unknown-clients;
)
)

  • Once done, there are many ways to have fun. The first is through Iptables (a packet filtering module, included in the Linux kernel), make all traffic coming / going to a team of "bad network" is always redirected to another machine that we decide. The result is that when our neighbors surf the Internet, go to the page you will always end up in the one in the direction we have chosen. I leave readers to think about what would be the most fun page to do that. We might even make ourselves, for example by a warning from the CIA, informing them that they will be investigated by the road "dangerous."

/sbin/iptables -A PREROUTING -s 192.168.0.0/255.255.255.0 -p tcp -j DNAT --to-destination 64.111.96.38

  • But this man has come up with another way to "have fun", even more original. You install Squid on your computer, a web proxy that is used in many networks as an intermediary between users and the Internet, combined it with mogrify, a script of image processing package ImageMagik, which allows, from the command line, perform operations on images, such as resize, rotate, etc.. In fact, he has used to turn it vertically all the images that are downloaded from the Internet. Then with the above trick, has redirected the navigation of its neighbors to the proxy. The process is transparent for users surfing, and the result is very curious:

La Web del revés (click para ampliar)
The setback Website (click to enlarge)

Script to "tweak" the images

#!/usr/bin/perl
$|=1;
$count = 0;
$pid = $$;
while (<>) {
chomp $_;
if ($_ =~ /(.*\.jpg)/i) {
$url = $1;
system("/usr/bin/wget", "-q", "-O","/space/WebPages/images/$pid-$count.jpg", "$url");
system("/usr/bin/mogrify", "-flip","/space/WebPages/images/$pid-$count.jpg");
print "http://127.0.0.1/images/$pid-$count.jpg\n";
}
elsif ($_ =~ /(.*\.gif)/i) {
$url = $1;
system("/usr/bin/wget", "-q", "-O","/space/WebPages/images/$pid-$count.gif", "$url");
system("/usr/bin/mogrify", "-flip","/space/WebPages/images/$pid-$count.gif");
print "http://127.0.0.1/images/$pid-$count.gif\n";
}
else {
print "$_\n";;
}
$count++;
}

  • Mogrify changing parameters, you can also make all the images downloaded from Internet neighbors from being blurred, to get what he calls the Internet blurry.

La Web difuminada (click para ampliar)
Web blurred (click to enlarge)

In short, when you stand to use neighbor's wireless network, keep in mind that not only you, the you see, but he also sees you to you and may acabéis be the target of his jokes. So do not despair focus the image on the monitor, because they may see the blur any other cause ...


Deals in other equipment ...



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