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Bug #19113 HTTP status 200 returned on HTTP CONNECT when mod_proxy not in use
Submitted: 2002-08-26 15:14 UTC Modified: 2005-12-14 11:42 UTC
Avg. Score:4.7 ± 0.9
Reproduced:34 of 34 (100.0%)
Same Version:18 (52.9%)
Same OS:17 (50.0%)
From: php_new at jdc dot parodius dot com Assigned:
Status: Not a bug Package: Apache related
PHP Version: 3.x, 4.x, 5.x OS: All
Private report: No CVE-ID:
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 [2002-08-26 15:14 UTC] php_new at jdc dot parodius dot com
I believe the following to be a severe bug which relates directly to PHP4 and Apache 1.3:

For those of you unfamiliar with HTTP, there is an HTTP command called "CONNECT" which is intended for use with HTTP proxying. Via telnet, one can test for proxy capability by doing the following (input is in bold): 

$ telnet 80
Trying ###.###.###.###...
Connected to
Escape character is '^]'.

Now hit [Enter] twice. If your Apache configuration is proper (and without mod_proxy installed), you should get the following response:

HTTP/1.1 405 Method Not Allowed

However, this is where the bug shows up.  Here are the pre-requisites for it to appear:

Must have PHP4 module loaded. 
Must have index.php listed in Apache DocumentIndex directive.
Must have index.php file in the DocumentRoot of the website you're connecting to (in the above example, 

The result of the above HTTP CONNECT when all of the above pre-requistes are met:

HTTP/1.1 200 OK
[HTTP headers here]
[Contents of parsed index.php here; as if visiting the website!]

An HTTP response code of 200 should only be sent when the request was legitimate -- a HTTP CONNECT should not be legitimate just because the website in question has an index.php file. You can literally rename index.php to something else (even index.html!) and a correct HTTP status of 405 is returned.  I have read the HTTP RFC in full, and it is fairly vague when it comes to dealing with HTTP CONNECT -- however, the Status code section applies to all sections, therefore a Status code of 200 on an HTTP CONNECT when mod_proxy is not loaded is incorrect.

Again, this only happens with mod_php4 installed.

So why is this a big deal?  Well, a slew of online services use proxy scanners to ensure legitimate clients are being used to communicate with their servers; proxy scanners are also used for IRC.  The scanners look for a status code of 200 on an HTTP CONNECT.

There is a workaround, which is to add the following to your server configuration: 

<Location />
  <Limit CONNECT>
    Order deny,allow
    Deny from all

This bug may be directly related to bug #17424.

Footnote: If this is traced back to be a flaw in Apache's DSO code, then I expect to see it reported as such, so I can forward this entire thread on to the Apache team and make them deal with it.  Thanks.


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 [2003-01-19 04:57 UTC]
Well can you tell me why it is "severe"?

Okay it is maybe not correct that it reacts on any string
but basicly why should it not react on


This could be a valid request if the server has loaded
mod_tinte v1.0 or whatever. If you dislike the feature
you can always check for a valid ("from your point of
view") request method from within your scripts.

 [2003-01-22 05:14 UTC] karabass at mitino dot ptt dot ru
It *is* severe because when I see in apache access_log a message like this: - - [22/Jan/2003:01:25:48 +0300] "CONNECT maildelivery.somewhere:25 HTTP/1.0" 200 44623 "-" "-"
it is threatening enough for me to put away what I was doing and start staring at my httpd.conf. And that only takes 3-4 hours to just find this bug-report and make myself comfortable about this new "PHP feature".
 [2003-03-16 06:40 UTC] psi-jack at myrddincd dot com
I've been testing out all the comments mentioned in this report.

The findings I have, is with Apache 1.3.27, and various modules. The modules I use is mod_php 4.3.0, mod_perl 1.27, mod_mp3 0.39, and for mod_perl, I had HTML-Mason and AxKit, and various other non-advertising mod_perl modules.

What did I find? With all the mentioned modules loaded, I get the same results as mentioned within these comments.

Etc, all these, provide the default page, wether it's a DirectoryIndex, or directory listing itself.

I unloaded mod_php, as per this bug was about. Still, same results. Once I unloaded mod_perl, however, the problem went away. I started getting 501's with those requests.

mod_mp3 didn't seem to effect that at all.

My final conclusion, this is very likely to be an Apache DSO bug, and not related directly to PHP, since it occured with mod_perl as well. The only one thing I did not try, was unloading my perlmodules from mod_perl.
 [2003-06-03 22:17 UTC]
See comment by: [16 Mar 6:40am CST] psi-jack at myrddincd dot com 
 [2003-08-24 10:26 UTC] messi at toxis dot com
I added the following three lines to Apache's mod_dir. This is ugly but works fine for me. Unless there's another way to prevent mod_php4 from getting invoked I'll use this on my machines.
Dunno if this will work with mod_proxy but I guess so.

--- src/modules/standard/mod_dir.c
+++ src/modules/standard/mod_dir.c
@@ -118,4 +118,7 @@
 static int handle_dir(request_rec *r)
+    if (r->method_number == M_CONNECT)
+        return HTTP_NOT_IMPLEMENTED;
     dir_config_rec *d =
     (dir_config_rec *) ap_get_module_config(r->per_dir_config,

Use it at your own risk and only with Apache 1.3(.28)!
 [2003-12-03 16:24 UTC] uhlar at fantomas dot sk
I don't know the apache's interface to modules, But I think that either php should tell apache by initialization that it can handle GET, HEAD, and POST method, ot the php should
check whether it is able to process the method (CONNECT in this case) - if it does have handler for it. 
I think that php does not have handler for CONNECT by default, thus it should either reject the request or pass it to apache for later processing.

mod_perl probably has the same bug, but unless apache does have an interface for modules to specify which methods are they able to use AND ignores the methods, it is a bug od mod_php versus mod_perl...
 [2005-12-14 01:16 UTC] php_new at jdc dot parodius dot com
This bug still applies to PHP 5.x, apparently.  A user of mine just recently asked me why his Apache logs were showing HTTP 200 status codes with requests like "CONNECT" when mod_proxy isn't loaded, and I pointed him to this bug.

Could a developer please look at this?  This bug is over 3 years old (!).  Changing Status to Open...

 [2005-12-14 01:28 UTC]
Does this work for you too:

 [2005-12-14 10:21 UTC]
Not PHP problem.
 [2005-12-14 11:42 UTC] php_new at jdc dot parodius dot com
As mentioned a couple years ago, this may have gotten fixed somewhere along the lines in Apache (or possibly PHP).

I just built a test system using FreeBSD 6.0, Apache 2.0.55, and PHP 5.1.1 (as a module) and *cannot* get this bug to appear.

But hear me out on this one if you could.  :-)

Reason I have a hard time believing it's an Apache bug: if it was an issue with interpreted handlers (such as PHP and mod_perl -- see one of the other users' comments), then I would also expect the exact same bug to appear when using mod_include (for server-parsed HTML documents).  But this doesn't happen.

Reason I have a hard time believing it's a PHP bug: because the problem seems to have disappeared (at least on my test setup).  Also, because one of the other users stated that he had the same problem with mod_perl loaded (but not with mod_php).

So either this got fixed in a PHP update (possibly mod_perl is still broken then!), or an Apache update (more than likely an Apache APR update).

I'm not going to sift through 3 years of ChangeLogs for PHP and Apache to try and track this down, especially since I don't keep up-to-date with *every* ChangeLog entry.

I'm fine with this being kept in Bogus status, but if someone has ideas as to how this got fixed (and more importantly, in where) then it'd be great if they could chime in here.  I'd feel better knowing where this bug was (Apache vs. PHP), rather than just some PHP developer telling me "not a PHP problem".

Finally, I'm changing the OS to "All" because this problem had been confirmed to exist on Win32 as well, not just UNIX.
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