George Gallen on 11 May 2006 21:00:28 -0000


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RE: [PLUG] Apache server not serving...


Is there a setting somewhere in the httpd.conf file that limits
how large of a file can be served? But I would think this would
cause an error. I'm going to see if I can create a very small
image file, and see if that one sneaks through.

In looking at the tcp traffic when I use wget to try to access a page with an image.
I see the the request, and the headers for the image file are sent, and the beginning of the file is sent,
  then it gets stuck. the http packet header (not the tcp headers) gives the correct filename, and
  the correct file length, and the part up to where it get's stuck is what the beginning of that
  image looks like.

>From the header side, there are packets being sent from the server to the client, but
  the client never sends back a ack of those packets, so the server keeps sending the same
  packet over and over every few seconds until the client side times out.

What is weird, is I had tcpdump running on both sides, both sides showed the same thing, packets
  being sent from the server, being received by the client, but no reply packet from the client
  back to the server. All the IP addressing looked correct, so it doesn't look like our corp
  filewall is stopping anything.

Very strange...


> -----Original Message-----
> From: plug-bounces@lists.phillylinux.org
> [mailto:plug-bounces@lists.phillylinux.org]On Behalf Of Stephen Gran
> Sent: Wednesday, May 10, 2006 1:29 PM
> To: plug@lists.phillylinux.org
> Subject: Re: [PLUG] Apache server not serving...
> 
> 
> I have two ideas about your arrangement that may help shed some light.
> Either or both may, of course, be wrong :)
> 
> First: multihoming hosts properly is difficult, and it may be routing
> issues causing things to respond on the wrong interface.  This seems
> unlikely, since most things are served over the second 
> interface - I am
> just wondering if the images are served from an external href on th
> eother interface.

by an external href, I take it you pointing to an image file that is not
on the server, which is no, these images are on the server.

> 
> Second: If the firewall blocks icmp, MTU discovery may be failing for
> large packets, leading to an apparent connection hang.  Since
> connections work for the most part, but large (relatively) transfers
> fail, this is where I would start looking.

I would think that most websites block icmp these days, so wouldn't that
mess with a lot of websites?

George
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