Topic awaiting preservation: 403 Error on Repetitive Request

On this site I've been working on, we've run into a snag. It seems that if a file is repeatedly requested in a short amount of time, a 403 error is reported and you're forbidden from reading any document for the next 20 seconds or so.

Specifically, here's how it happens. I'm using a PHP script to render dynamic image headings on most pages. Each heading is called basically like so: <img src="heading.php?Text">. So for each img tag, heading.php is being called another time. On a couple of pages, we've got about a dozen of these img tags. It's these pages with a lot of calls to heading.php that trigger the problem. Those with only a couple don't have a problem.

Now, it can't be heading.php itself that's causing the problem. I can strip out the img tags and refresh several times in a row and get the same 403 error. In fact, I've created a plain html document with nothing but the basic html structure and the word "Test" in it and refreshed about 6 times and gotten the 403.

Problem is, another developer tries to do that and doesn't get it, but he's using IE (I'm using Firefox) and IE, in my experience, is more persistent with caching a page. I don't think he's actually reloading the page every time he hits refresh, so he doesn't piss off the server and get the 403. He does get it, however, with the pages containing several img headings. So, he's inclined to blame the img headings and wants me to replace them all with static images, which I don't have to tell you is a huge PITA.

I don't have this problem with a copy of the site on my own server, but it's a big problem on theirs. It has to be something on the server somewhere. Does anyone have any idea how this could be dealt with?

Ok, I think I am going to guess that this is an apache server.

There might be something like mod_dosevasive installed. This will limit the number of concurrent connections by a host in a given amount of time, by throwing a 403 error, and it might ultimately blacklist you.

You are most likely hitting this and it is triggering a 403 to stop you from crushing the server. You should ask the host about the specific settings, and they might be able to help you to work with this.

Dan @ Code Town

(Edited by WarMage on 08-08-2005 22:53)

(Edited by WarMage on 08-08-2005 22:59)

I'll pass this on to those in charge, thanks.

Wes - I'd be curious to know if that's what it was...

As I've been told, that seems to be the culprit. No word on it being fixed, however.