Topic: Unable to get to web site

[icemannz]

Hi all,
I have a site which is running through an SME version 7 server.
The server is running as a gateway and server.
The users are able to get to any web page except for one.
They use a web site which they login to and download various Jpg files.
They are able to get to the web site, login and find the files that they want to download,
But when they go to download them, it seems to loose its connections and times out with an error in the browser.

When going through this and testing, I can see that the webpage that they login to is www.dynamicgraphics.co.nz
What I did notice is that the web page is dynamicgraphics.co.nz up until they are about to download the Jpg file they request and then the web page changes to: i18.stockmediaserver.com/...
So I believe that the session is somehow getting broken.

Does anyone know a way around this issue ?
Is it possible to tell the SME Server to not Proxy the site or something ?
I can get to this web site from any other system and download the files, but as soon as they are behind the SME server, it doesn't work.

Any help would be appreciated.

[purvis]

FWIW
ping the sites
ping www.dynamicgraphics.co.nz
ping dynamicgraphics.co.nz

ping i18.stockmediaserver.com
ping stockmediaserver.com


notice the ip addresses
does this help

[purvis]

you might want to ping those sites from the remote computers as well to see what they are showing

[mmccarn]

I recently learned about a design problem with TCP that shows up as timeouts in qpsmtpd connections and/or websites that work for small packets but fail for large data transfers.

Here is a bug report on this talking about qpsmtpd timeouts:
http://bugs.contribs.org/show_bug.cgi?id=6888

Here are some more references:
http://lartc.org/howto/lartc.cookbook.mtu-mss.html
http://packetlife.net/blog/2008/aug/18/path-mtu-discovery/

If any network segment between you and the image server has a packet size less than 1500 and handles MTU discovery incorrectly, you'll see the behavior you're describing.

You can test this from a windows workstation using:
ping -l 1472 -f <image server name or ip>

* If the above command reports fragmentation needed, this is your problem.
* If the above command simply gives you "Reply from...", then I'm wrong.

Note: "pinging" with a 1472 byte message tests an MTU setting of 1500; ping adds 28 bytes of overhead to each packet - so pinging with a message size of 1472 tests an MTU of 1500 (1472+28=1500).

Usually, the problem will be a PPPoE connection with an MTU of 1492 somewhere between you and the "failing" site - if so, this "ping" would give "Reply from...":
ping -l 1464 -f <image server name or ip>

but this one would report "fragmentation needed":
ping -l 1465 -f <image server name or ip>

[jameswilson]

Have you tried turning off the web proxy in the admin panel.
I had an issue with a zencart site that was causing login issues. While i look into it i disabled the http proxy and all is well. I do want it back on though long term