zuvshuurulgui ashiglaad bgaa humuuseer jaahan togloom hiij boloh um bna. (IT medleg jaahan shaardagdah baih :P)
I’m starting here by splitting the network into two parts, the trusted half and the untrusted half. The trusted half has one netblock, the untrusted a different netblock. We use the DHCP server to identify mac addresses to give out the relevant addresses.
/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;
}
}
IPtables is Fun!
Suddenly everything is kittens! It’s kitten net.
/sbin/iptables -A PREROUTING -s 192.168.0.0/255.255.255.0 -p
tcp -j DNAT --to-destination 64.111.96.38
For the uninitiated, this redirects all traffic to kittenwar.
For more fun, we set iptables to forward everything to a transparent squid proxy running on port 80 on the machine.
/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
That machine runs squid with a trivial redirector that downloads images, uses mogrify to turn them upside down and serves them out of it’s local webserver.
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++;
}
Then the internet looks like this!
esvel budgeruulchihej boloh um bna. (replace flip with -blur 4 you get the blurry-net )
