Site Blocker Work Around CGI help

Plankton has asked for the wisdom of the Perl Monks concerning the following question:

Friends,

While at work I am not able to access certain web sites because they are considered fun. So I thought I would set up a CGI on my system at home that I could bounce my request to these blocked sites off of. The problem I am having is that I don't know how I should deal with <FORM>'s action attributes.

Here's what I have so far ...

#!/usr/local/bin/perl -w
use strict;
                                                                      
+                                                                     
+        
use WWW::Mechanize;
use CGI;
my $cgi = new CGI;
my $mech = WWW::Mechanize->new();
my $scriptName = $ENV{'SCRIPT_NAME'} || $0;
my ( $requestURI, $QS ) = split /\?/, $ENV{'REQUEST_URI'} || $0;
my $url = $cgi->param('url') || 'http://localhost/';
$mech->get( $url );
my $content = $mech->content;
$content =~ s/<HTML>//ig;
$content =~ s/<\/HTML>//ig;
$content =~ s/<BODY>//ig;
$content =~ s/<\/BODY>//ig;
my @lines = split /\n/, $content;
print $cgi->header ();
print "<base href=$url>\n";
print $cgi->start_html( "WAY $scriptName" );
for my $line (@lines) {
        if ( $line =~ /a href/i ) {
                if ( $line =~ /<a href=(['"])http/i ) {
                        $line =~ s/<a href=(['"])/<a href=$1http:\/\/l
+ocalhost\/cgi-bin\/way.pl?url=/ig;
                } else {
                        $line =~ s/<a href=(['"])/<a href=$1http:\/\/l
+ocalhost\/cgi-bin\/way.pl?url=$url/ig;
                }
        }
        print $line;
}
print "<!-- \n";
while ( my ($key, $val) = each %ENV) {
        print "$key = $val\n";
}
print "-->\n";
print $cgi->end_html;
[download]

I want to be able to logon via this URL ...

http://localhost/cgi-bin/way.pl?url=http://www.itsyourturn.com/iyt.dll
+?status?p=1
[download]

... and of course be able to play some chess once i logon.

Thanks!

Plankton: 1% Evil, 99% Hot Gas.

Comment on Site Blocker Work Around CGI help Select or Download Code

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Re: Site Blocker Work Around CGI help by tachyon (Chancellor) on Jul 01, 2004 at 05:40 UTC
You will get caught and the brown stuff will probably hit the fan. You have been warned. Anyway save yourself some effort and try one of the online anonymisers here You may well find one that is unblocked. Or you may like to use some of the GNU stuff that already does this like httpbridge . httpbridge is also 'good' because it uses https which is opaque to logging software ie all that is visible is the CONNECT mysite.com:443 pipe - what you do inside that pipe can't be seen. Anyway if you don't find satisfaction anywhere above at least you will be able to see how they do it which is in essence this: Set up a socket server that listens on port 80 at mysite.com This socket server will accept requests in the form http://mysite.com/http://othersite.com When your server gets a request you will need to make a few modifications to it before passing it right along. Do that ;-) Make a socket to othersite.com and forward on the slightly modified request almost verbatim. When you get the data back pass it straight back to the client unless it is text/html. If it is text/html replace every LINK with http://mysite.com/http://othersite.com/LINK then pass it back. That way all the links pass back to you* except the ones that you will miss... It is not actually very hard but you do need to understand HTTP headers pretty well. To get http://somesite.com/index.htm you connect a socket to somesite.com and ask for /index.htm. So you will need to modify a header that will look something like: `[GET\|POST] http://othersite.com/LINK HTTP1/1.1 Host: mysite.com Content-Length: 1234 .... to one that looks like [GET\|POST] /LINK HTTP/1.1 Host: othersite.com Content-Length: ACCURATE!` [download] Once you have modified the header you just make your socket to othersite.com and pipe the request through. Note that hard coded links like http://google.com in a page you serve up will end up as: http://mysite.com/http://othersite.com/http://google.com. You need to be smart enough to deal with this sort of issue, which is one of the many you will come across. It is actually quite hard to get it to work really well due to the complexities of javascript and CSS and cookies. You know you are doing well when hotmail works which requires a man in the middle attack..... BTW I am adding your URL to our blocklist :-) cheers tachyon	[reply] [d/l]
Re: Site Blocker Work Around CGI help by bart (Canon) on Jul 01, 2004 at 07:18 UTC
I want to be able to logon via this URL ... `http://localhost/cgi-bin/way.pl?url=http://www.itsyourturn.com/iyt.dll +?status?p=1` [download] Eh? It won't work on localhost. Your "proxy" must reside on a server outside of the firewall. And of course, the domain your proxy is on may not be blocked, itself.	[reply] [d/l]
Re^2: Site Blocker Work Around CGI help by Grygonos (Chaplain) on Jul 01, 2004 at 12:45 UTC
Or just ssh into a *nix box and use lynx ... that's what I do :/ Grygonos	[reply]
Re^3: Site Blocker Work Around CGI help by arden (Curate) on Jul 01, 2004 at 15:13 UTC
You don't even have to use lynx, ssh can pipe X-windows through the encrypted channel and display it on your local monitor! Go ahead and use Netscape or play Bolo. . . Ahem, this is all in theory, as I have never done anything like it, no no, not me. I'm not condoning this at all. :^) - - arden.	[reply]