MS changes IE and IIS TCP/IP rules

[Michael Havens]

Is this why I sometimes get mail that is two days or more old even though=
 we=20
do not use IE?

>
> Subject: MS changes IE and IIS TCP/IP rules
> Date: Sun, 5 Jan 2003 17:13:14 -0800 (PST)
> From: Matt Alexander <m@netpro.to>
> To: PLUG-AZ <plug-discuss@lists.plug.phoenix.az.us>
>
> Interesting...  Microsoft is using TCP/IP in a way that makes IE respon=
d
> faster to IIS and slower to non-IIS webservers:
>
> http://grotto11.com/blog/?+1039831658
>
> Could someone with IE and IIS please verify this?  A dump of TCP/IP
> traffic with different versions of IE and IIS would be ideal.
>
> Of course covered on Slashdot:
>
> http://slashdot.org/article.pl?sid=3D03/01/05/2025254
>
> This post sums things up:
>
>  The parent +5 post is flat out wrong. This is not about persistant
>  connections, which is a high-level HTTP feature that keeps a connectio=
n
>  open so that the browser can send more requests. This is about a
>  low-level TCP hack that IE uses to get a small speed boost on IIS
>  servers, while breaking TCP standards compliance.
>
>  If I read the article correctly, instead of creating a new TCP connect=
ion
>  and then sending a request, IE sends the request immediately without
>  bothering to finish the TCP handshake. Microsoft IIS web servers deal
>  with it automatically, and it is faster because it saves a round-trip
>  wait for the ACK and the following requset.
>
>  The down side is that non-IIS servers have no clue what this incoming
>  packet is. It must be invalid because it is not a SYN. So it gets thro=
wn
>  away, and the server might or might not reset the connection. If a
>  non-IIS server resets the connection, IE goes with a standard TCP
>  handshake and has wasted only the round trip time for the request pack=
et
>  and the RST. But if the server swallows the invalid packet and does no=
t
>  send a RST, then Internet Explorer will just sit around for a few seco=
nds
>  until it times out and falls back to a standard TCP conection.
>
>  The summary is that IE is breaking the TCP protocol for a small speed
>  boost when connecting to IIS servers. It results in a small speed pena=
lty
>  when connecting to most non-IIS servers. When connecting to non-IIS
>  servers that do not reset the connetion, it results in a very noticabl=
e
>  delay.
>
>  It could also be a potential security risk, because if this is true, t=
hen
>  it makes it very easy to IP-spoof a HTTP request against IIS (since th=
e
>  request is a self-contained packet instead of a long connection
>  sequence).
>
>
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--=20
:-)~Mike~(-: