Diary of a Bad Golfer

Sure, you could use encryption on your wireless connection, but why not have some fun with them instead?  I’m sure everyone has browsed admin shares, printed 100’s of goatse/tubgirl/lemon party pictures to printers and other random immature things - but this is way more clever.

Make all their images load upside down…

The first thing to do is divide the network into 2 parts - trusted and untrusted.  Use the DHCP server to identify MAC’s and give out relevant ip’s.

/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;

host trusted1 {
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;

}
}

Now, set iptables to farward everything to a transparent squid proxy running on port 80.

/sbin/iptables -A PREROUTING -s 192.168.0.0/255.255.255.0 -p tcp -m tcp --dport 80 -j DNAT --to-destination 192.168.0.1

The machine runs squid with a redirector that downloads images, uses mogrify to turn them upside down and then serves them out of it’s local web server.

The redirection script

#!/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++;

}

End Result:

Click for full sized image.