Re: Error with SSL certificates and SSL Filter

[Markus Müller]

Hi Dario and everyone.

CONCLUSION: POE::Filter:SSL works as designed.
Your explanation shows that there is no problem in POE::Filter::SSL, you 
describe the wanted and necessary behavior of SSL and the implementation 
of SSL proxying in browsers.

If you configure in a SSL proxy in a browser then it WON'T do SSL with 
the proxy for HTTP Connections. The browser will only send for HTTPS 
requests a line to the proxy with the question "Please connect mit 
directly to IP:Port", and it then relies that it is connected DIRECTLY 
(on tcp/ip level) to the SSL server. It then tries to do SSL with the 
target server, and NOT with the proxy. The proxy is only intended to 
relay tcp raw data. And HTTP connections can't be encrypted at all by 
configuring a SSL proxy!

Further: If you want to encrypt HTTPS requests, then what you want to do 
is (in the sight of the browser) a man-in-the-middle attack. For this to 
work you need to act as a tcp relay as mentioned but don't do a raw 
forwarding of tcp data. You then need to do SSL to the target and a 
futher SSL to the client. The browser will determine this as an attack, 
if a appropriate certificate is not generated on the fly the browser 
trusts in.

Nevertheless this is possible with POE::Filter:SSL. You are able to 
switch during runtime the filter (see IMAP-Relay example on the CPAN 
search): You can interpret the mentioned "CONNECT"-Line from the 
browser, do the creation of a ssl certificate, and then switch the 
filter to ssl. On serverside you just do a SSL client handshake and 
forward the uncrypted data to the client ssl connection. But only for 
HTTPS connections; as already said HTTP is not possible to encrypt this way.

-> As you can see: It won't be getting working by just add a ssl filter 
before the HTTPD!

An example solutions for the HTTPS proxying can be found on 
http://crypto.stanford.edu/ssl-mitm/. Please read here the documentation 
and on how proxying in browser works.

Regards,
Markus Mueller

Sorry for the delay.

Yes your example works well without the proxy. The browser is a 
Firefox 3.0.17 under Ubunut 8.04 (is a virtual machine...). If I try 
your example with Firefox's proxy enable I get the same error.

And the proxy is under Ubuntu 10.10

I don't know so much about HTTPS protocol and communications, Does It 
makes sense for you?

Regards,

Dario.

On 25/05/11 16:53, Markus Müller wrote:
Hello Dario,

did this help?

Regards,
Markus Mueller

Did you use my example as proxy or did you disable the proxy in 
browser and access it with "https://server:ip/"; ?

Did I right understand that firefox work but other browser not?

Which distribution and version of linux do you use?

Regards,
Markus Mueller

I tried your example and the result was the same error. I thought 
that there was a problem with the server because even with your 
script I didn't see any screen on the server to accept the 
certificate.

My problem is that the browser enters in a infinite loop after the 
page request. And no page related to any certificate is shown. I am 
usgin Firfox 3.0.17 and the certificate with apache went fine, the 
screen appeared and I could accept the certificate.

Does It make sense?  Do I forgot something, maybe a parameter of 
the filter?

Regards and thank you for the help.

Dario.

On 24/05/11 12:35, Markus Müller wrote:
Hi Dario,

I am also using untrusted certificates. There is no issue on 
server at all for that, only on client side. You have to accept 
the certificate in the browser, the server don't do anything about 
that. I just don't understand why you think it could be anything 
about untrusted certificates... Everything I mentioned is that in 
my test the message only occures if I connect with a browser which 
aborts the connection cause the certificate is not accepted by the 
client (= the browser).

What exactly is your problem? Maybe your browser don't allow 
untrusted certificates from a proxy server?

Did you try my example? It makes a https server and not a https 
proxy. Please try if http server works, maybe you just have a 
problem in your browser about poxying and untrusted certificates.

Regards,
Markus Mueller

You are right Markus, I am using a unstrusted certificate. Is 
there any way to use the SSL filter with untrusted certificates? 
I know other libs like LWP can deal with them.

If this is a TODO or a bug I can help you fixing this on the POE 
SSL Filter code :)

Regards,

Dario.

On 24/05/11 11:35, Andy Jenkinson wrote:
When doing something similar, I seem to remember I got this 
error when attempting to connect via HTTP too. I could be making 
that up though.

Cheers,
Andy

On 24 May 2011, at 10:07, Markus Müller wrote:

Hello everyone,

I've tried the following program and it works under Debian 
Squeeze.

The message "POE::Filter::SSL: UNEXPECTED ERROR: ERR1:0 ERR2:1 
HINT: Check if you have configured a CRT and KEY file, and that 
both are readable at /usr/share/perl5/POE/Wheel/ReadWrite.pm 
line 280" occures in my test only if the browser aborts the 
connection during SSL handshake because the certificate is 
untrusted. In any other case I can see the data the server is 
returning.

Dieser Verbindung wird nicht vertraut

Sie haben Firefox angewiesen, eine gesicherte Verbindung zu 
saytest.priv.de:82 aufzubauen, es kann aber nicht überprüft 
werden, ob die Verbindung sicher ist. Wenn Sie normalerweise 
eine gesicherte Verbindung aufbauen, weist sich die Website mit 
einer vertrauenswürdigen Identifikation aus, um zu garantieren, 
dass Sie die richtige Website besuchen. Die Identifikation 
dieser Website dagegen kann nicht bestätigt werden.

Was sollte ich tun?

Falls Sie für gewöhnlich keine Probleme mit dieser Website 
haben, könnte dieser Fehler bedeuten, dass jemand die Website 
fälscht. Sie sollten in dem Fall nicht fortfahren.

Much regards,
Markus Mueller

#!perl

use strict;
use warnings;
use Socket;
use POE qw(
   Wheel::SocketFactory
   Wheel::ReadWrite
   Driver::SysRW
   Filter::SSL
   Filter::Stackable
   Filter::HTTPD
   Component::Server::TCP
);
POE::Component::Server::TCP->new(
    Alias        =>  "web_server",
    Port         =>  82,
    #ClientFilter =>  'POE::Filter::HTTPD', ##WITHOUT HTTPD 
FILTER THERE ISN'T HTTP HEADERS!!!
    ClientFilter =>  POE::Filter::Stackable->new(
        Filters =>  [
            POE::Filter::SSL->new(crt =>  'sslkeys/server.crt', 
key =>  'sslkeys/server.key'),
            POE::Filter::HTTPD->new(),
        ]
    ),

    ClientInput  =>  \&handle_http_request,
    InlineStates =>  {got_response =>  \&handle_http_response,},
);

sub handle_http_request {
   my ($kernel, $session, $heap, $buf) = @_[KERNEL, SESSION, 
HEAP, ARG0];
   my $content .= "Your URL was: ".$buf->uri."<hr>"
     if (ref($buf) eq "HTTP::Request");
   $content .= localtime(time());
   my $response = HTTP::Response->new(200);
   $response->push_header('Content-type', 'text/html');
   $response->content($content);
   $_[HEAP]{client}->put($response);
   $_[KERNEL]->yield("shutdown");
};

POE::Kernel->run;
exit;

I am making a proxy and it must support the https protocol. I am
trying to enable SSL feature in the server side with this 
command:

POE::Component::Server::TCP->new(
    Alias        =>  "web_server",
    Port         =>  LISTEN_PORT,
    #ClientFilter =>  'POE::Filter::HTTPD', ##WITHOUT HTTPD 
FILTER
THERE ISN'T HTTP HEADERS!!!
    ClientFilter =>  POE::Filter::Stackable->new(
        Filters =>  [
            POE::Filter::SSL->new(crt =>  
'sslkeys/server.crt', key =>
'sslkeys/server.key'),
            POE::Filter::HTTPD->new(),
        ]
    ),

    ClientInput  =>  \&handle_http_request,
    InlineStates =>  {got_response =>  \&handle_http_response,},
);

But when a https request hit the server I get the following 
error:

POE::Filter::SSL: UNEXPECTED ERROR: ERR1:-1 ERR2:1 HINT: Check 
if you
have configured a CRT and KEY file, and that both are readable at
/usr/share/perl5/POE/Wheel/ReadWrite.pm line 280


I don't know what this error means because the files has the
permission flags set to 777. Are required some special certs?

Thanks in advance.