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  1. Jan 26, 1998
    • brian's avatar
      PR: · b6ba7d5b
      brian authored 
      If SCO's going to break their links, I'm not going to go searching for where they
moved it to.

Cold and rainy and dark.
ml" -->

<H1 ALIGN="CENTER">Connections in the FIN_WAIT_2 state and Apache</H1>
<OL>
<LI><H2>What is the FIN_WAIT_2 state?</H2>
Starting with the Apache 1.2 betas, people are reporting many more
connections in the FIN_WAIT_2 state (as reported by
<code>netstat</code>) than they saw using older versions.  When the
server closes a TCP connection, it sends a packet with the FIN bit
sent to the client, which then responds with a packet with the ACK bit
set.  The client then sends a packet with the FIN bit set to the
server, which responds with an ACK and the connection is closed.  The
state that the connection is in during the period between when the
server gets the ACK from the client and the server gets the FIN from
the client is known as FIN_WAIT_2.  See the <A
HREF="ftp://ds.internic.net/rfc/rfc793.txt">TCP RFC</A> for the
technical details of the state transitions.<P>

The FIN_WAIT_2 state is somewhat unusual in that there is no timeout
defined in the standard for it.  This means that on many operating
systems, a connection in the FIN_WAIT_2 state will stay around until
the system is rebooted.  If the system does not have a timeout and
too many FIN_WAIT_2 connections build up, it can fill up the space
allocated for storing information about the connections and crash
the kernel.  The connections in FIN_WAIT_2 do not tie up an httpd
process.<P>

<LI><H2>But why does it happen?</H2>

There are numerous reasons for it happening, some of them may not
yet be fully clear.  What is known follows.<P>

<H3>Buggy clients and persistent connections</H3>

Several clients have a bug which pops up when dealing with
<A HREF="../keepalive.html">persistent connections</A> (aka keepalives).
When the connection is idle and the server closes the connection
(based on the <A HREF="../mod/core.html#keepalivetimeout">
KeepAliveTimeout</A>), the client is programmed so that the client does
not send back a FIN and ACK to the server.  This means that the
connection stays in the FIN_WAIT_2 state until one of the following
happens:<P>
<UL>
        <LI>The client opens a new connection to the same or a different
            site, which causes it to fully close the older connection on
            that socket.
        <LI>The user exits the client, which on some (most?) clients
            causes the OS to fully shutdown the connection.
        <LI>The FIN_WAIT_2 times out, on servers that have a timeout
            for this state.
</UL><P>
If you are lucky, this means that the buggy client will fully close the
connection and release the resources on your server.  However, there
are some cases where the socket is never fully closed, such as a dialup
client disconnecting from their provider before closing the client.
In addition, a client might sit idle for days without making another
connection, and thus may hold its end of the socket open for days
even though it has no further use for it.
<STRONG>This is a bug in the browser or in its operating system's
TCP implementation.</STRONG>  <P>

The clients on which this problem has been verified to exist:<P>
<UL>
        <LI>Mozilla/3.01 (X11; I; FreeBSD 2.1.5-RELEASE i386)
        <LI>Mozilla/2.02 (X11; I; FreeBSD 2.1.5-RELEASE i386)
        <LI>Mozilla/3.01Gold (X11; I; SunOS 5.5 sun4m)
        <LI>MSIE 3.01 on the Macintosh
        <LI>MSIE 3.01 on Windows 95
</UL><P>

This does not appear to be a problem on:
<UL>
        <LI>Mozilla/3.01 (Win95; I)
</UL>
<P>

It is expected that many other clients have the same problem. What a
client <STRONG>should do</STRONG> is periodically check its open
socket(s) to see if they have been closed by the server, and close their
side of the connection if the server has closed.  This check need /export/home/cvs/CVSROOT/cvsedit


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@80009 13f79535-47bb-0310-9956-ffa450edef68
      b6ba7d5b
    • brian's avatar
      PR: · 121bd13d
      brian authored 
      Make all references complete.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@80006 13f79535-47bb-0310-9956-ffa450edef68
      121bd13d
    • brian's avatar
      PR: · 16ac5365
      brian authored 
      
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@80004 13f79535-47bb-0310-9956-ffa450edef68
      16ac5365
  3. Jan 25, 1998
    • dgaudet's avatar
      - no need to use stat() since r->finfo is already what we need · 66db3449
      dgaudet authored 
      - no need to play with atime/mtime crud, the web server doesn't preserve
    that info normally anyhow
- deal with r->finfo.st_mode == 0 || !r->filename (i.e. not a disk file)
- don't reference mime_module.type_checker, this should be controlled by
    the ordering within Configuration
- work properly with multiple vhosts
- doc update: even prior to this patch, the code was disabled if there
    was no MimeMagicFile directive.


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      66db3449
  5. Jan 23, 1998
  7. Jan 22, 1998
  9. Jan 20, 1998
    • brian's avatar
      PR: · 725d30f3
      brian authored 
      First stab at updating.  Other windows developers need to make sure this
still makes sense!  Notably, does the line break problem mean that the .tar.gz
distribution can't be compiled on NT?


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      725d30f3
  11. Jan 07, 1998
  13. Dec 29, 1997
  15. Dec 22, 1997
    • Marc Slemko's avatar
      Misc cleanups: · 4b319f37
      Marc Slemko authored 
      	- cleanup HTML, <e> --> <em>
	- remove bogus security warning about LockFile
	- add warning about possible denial of service attack with
	  LockFile in world writable directory
	- remove security encouragement to use inetd; add warning that
	  inetd isn't well supported.

PR:
Obtained from:
Submitted by:
Reviewed by:


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      4b319f37
  17. Dec 21, 1997
  19. Dec 20, 1997
    • dgaudet's avatar
      Lars says: · bcd48d69
      dgaudet authored 
      some people are confused if they see the different naming conventions
for language negotiated documents (e.g. foo.html.en vs. foo.en.html)
and how a hyperlink to such a document should look like.
There's a PR about it (#1559) and I've seen several questions on
usenet about it.

I tried to clarify this issue in an extra paragraph in the
content-negotiation.html document (see attachment).

PR:		1559
Submitted by:	Lars Eilebrecht
Reviewed by:	Dean Gaudet


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  21. Dec 18, 1997
  23. Dec 16, 1997
  25. Dec 14, 1997
  27. Dec 07, 1997
  29. Dec 02, 1997
  31. Dec 01, 1997
  33. Nov 25, 1997
  35. Nov 15, 1997
  37. Nov 14, 1997
  39. Nov 12, 1997
  41. Nov 11, 1997
    • Martin Kraemer's avatar
      Citing Lars: · 8ccf4d70
      Martin Kraemer authored 
      Hi,

the attachment includes a reworked Apache manual with the
new virtual host documentation.

As Dean suggested I created a new directory named 'vhosts' and moved the
updated vhosts-in-depth etc. documents into the new directory, renamed
them and updated all other documents which refered to the old docs
(at least I tried to find all documents...).

Submitted by: Lars Eilebrecht <sfx@unix-ag.org>
Reviewed by:	 Martin Kraemer


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