Upside Down Ternet

Install the squid, apache, wget and imagemagick packages from the official repositories.

Create flip.pl, place it in your /usr/local/bin folder and make it executable:

/usr/local/bin/flip.pl

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

Next, while not necessary, does clean up the Squid configuration file a lot making it easier on the eyes

# sed -i "/^#/d;/^ *$/d" /etc/squid/squid.conf

Now, edit your squid.conf file and append this to the bottom

squid.conf

url_rewrite_program /usr/local/bin/flip.pl

Also find the line for http_port and make it now read

Finally, we have to create the folders for the images to be flipped in and set their permissions

The directory where the images are to be stored must be owned by the proxy user. Finally, add the http user to the proxy group

Verify that the http user is a member of the proxy group

or

Start/enable httpd.service and .

• Original Upside-Down-Ternet Link
• Ubuntu HowTo
• Transparent Proxy with DD-WRT
• Upside-Down-Ternet XKCD