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From Tim Wort <...@pobox.com>
Subject Re: [users@httpd] New discovery
Date Tue, 03 Dec 2002 01:42:33 GMT

One way that a router could cause this: first if the server is behind a
firewall that blocks all ICMP messages (a typical mistake by inexperienced
firewall admins) it is possible that a router between the server and the
client requires the the MTU of the packets be reduced. Most modern systems
send packets with the DNF (do not fragment) flag set. When fragmentation
is required on such a packet the router that requires this will return a
ICMP message to the sender requesting a reduced packet size. If the
firewall blocks this your data will appear to be sent but will never
arrive and only the logs (or using a sniffer beyond the router) on the
router will explain why the packets (ICMP messages) are dropped. Because
HTML is typically smaller amounts of data it will make it past the router
that requires fragmentation.

This type of problem is generally inconsistant depending on where the
packets need frgmentation, if its a long way down stream you will only see
it when talking with particualr machines (beyond the offending router) but
not from other parts of the network. If the offending router is close to
you it is possible you will see this problem with all larger files. Does
ftp work from the same client to youe server?



=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
=        Inkling Research Inc.      =
=    Tim.Wort@InklingResearch.com   =
=        Tim.Wort@pobox.com         =
=                                   =
=        Eschew Obfuscation         =
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=



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