Re: How do web servers handle dropped connections?

[Domenico De Vitto <dom () DEVITTO DEMON CO UK>]

There is quite a bit in the Apache FAQ about 'FIN_WAIT2' stated connections,
which as well as explaining the woes of FIN_WAIT2 stated connections,
also explains what happens at the TCP level when the connection gets dropped
mid conversation, e.g. they hit [STOP].

I thought it was very interesting, but I'm kinda sad.

Dom

-----Original Message-----
From: VULN-DEV List [mailto:VULN-DEV () SECURITYFOCUS COM]On Behalf Of H D
Moore
Sent: 26 August 2000 05:37
To: VULN-DEV () SECURITYFOCUS COM
Subject: Re: How do web servers handle dropped connections?


Walter Hop wrote:
> Hi,
>
> looking at the stars last night I was wondering: if I request a scripted
> page /blah.pl from a webserver, the server starts the perl interpreter and
> runs the script. What happens when the browser breaks the connection
> with the web server before the script has finished? Is the script allowed
> to execute fully and is the output being discarded afterwards, or is the
> process killed immediately? In other words, can server side scripts be
> aborted prematurely in this way - and for example corrupt open files or
> leave inconsistencies in a database?


In my experience I noticed that scripts that are parsed by an external
command (perl) will continue execution even after the client has
disconnected.  Scripts that are interpreted by  server modules (php)
will stop execution as soon as the client disconnects.  The above
observations are with Apache 1.3.x servers only, I have no idea what
IIS/Netscrape/*Server does.

-HD

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