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king_micah
Joined: 09 Jun 2003
Posts: 994
Location: OSU
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Posted: Tue May 25, 2004 7:00 pm
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Is this why I keep getting old forum pages loaded? I have to reload to get new pages loaded most of time, otherwise I get the old pages.
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RomSteady
Joined: 25 May 2004
Posts: 2
Location: Layton, UT
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Posted: Tue May 25, 2004 9:51 pm
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Most proxy servers respect the robots.txt file with regards to prefetching. If you know the agent string for the proxy causing the problems, you can even tailor the robots.txt to only stop that proxy from caching.
Your only other choice would be to set an expiration to the page in your meta tags.
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void
Joined: 13 Apr 2004
Posts: 1
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Posted: Wed May 26, 2004 12:07 am
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The webserver needs to send "Pragma: no-cache" in the HTTP headers.
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lx805
Joined: 26 May 2004
Posts: 2
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Posted: Wed May 26, 2004 1:43 am
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If you're using PHP, you can drop this code into your pages...
Code: | <?php
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
?> |
Hopefully proxy servers hitting this site will honor at LEAST one of these pragmas...
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Tempest
I Run this place.
ANN Publisher
Joined: 29 Dec 2001
Posts: 10461
Location: Do not message me for support.
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Posted: Wed May 26, 2004 2:31 pm
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lx805 wrote: | If you're using PHP, you can drop this code into your pages... |
Will this stop all caching, or just pre-fetching?
Quote: | Most proxy servers respect the robots.txt file with regards to prefetching. |
It has become obvious that some don't.
Quote: | If you know the agent string for the proxy causing the problems |
Unfortunately our logs are showing that most proxies are passing on the agent string of the proxy client.[/quote]
Let me explain the issue. ANN gets hammerred by errant bots and e-mail harvesters fairly often, sometimes these bots are really bad and cause some problems in terms of server load, bandwidth and banner clickthrough rates.
What we decided to do, was to set up a little script that catches robots that ignore the robots.txt guidelines. Its worked quite well, but unfortunately it seems to have also picked up, and subsequently banned, several proxy servers that pre-fetch.
I'm glad that most proxies follow the robots.txt guidelines for pre-fetching. It'd be a real headache if they didn't. But unfortunately some don't, and we're getting e-mails from people who have been banned from the site because their office proxy prefetched the dissallowed pages.
So, what I'm really looking for is to turn off pre-fetching and only pre-fetching, as opposed to all caching.
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RomSteady
Joined: 25 May 2004
Posts: 2
Location: Layton, UT
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Posted: Wed May 26, 2004 6:31 pm
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Quote: | Its worked quite well, but unfortunately it seems to have also picked up, and subsequently banned, several proxy servers that pre-fetch. |
Can you track back to one of the proxy server's that is prefetching and find out which proxy server they are using?
Because at this point, the only solution I can think of involves CAPTCHA images to "unban" an IP for a brief while.[/quote]
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Tempest
I Run this place.
ANN Publisher
Joined: 29 Dec 2001
Posts: 10461
Location: Do not message me for support.
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Posted: Wed May 26, 2004 11:08 pm
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RomSteady wrote: | Because at this point, the only solution I can think of involves CAPTCHA images to "unban" an IP for a brief while. |
The thought has ocurred to me. It's actually a pretty good idea and you reminding of it makes me want to do it.
But I'd still like to do whatever I can to minimize the number of people that need to use it.
-t
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Tempest
I Run this place.
ANN Publisher
Joined: 29 Dec 2001
Posts: 10461
Location: Do not message me for support.
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Posted: Wed May 26, 2004 11:12 pm
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RomSteady wrote: | Can you track back to one of the proxy server's that is prefetching and find out which proxy server they are using? |
Working on that. I'll update here when I find out.
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