Why would a url of example.com/n (where n is the same number repeated 500x) return a 403 error?

Question

I'm trying to add new functionality to my site which involves passing a whole bunch of parameters (could be hundreds of parameters) all encoded in base64 format. When I attempt the new URL I get an error 403 (access denied).

I verified this to be a length issue because I then tried accessing the same domain but instead of base64 code, I used numbers after the URL and I still get the same error.

If you feel like scrolling across, you'll see the URL I try to access:

http://example.com/1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111

I was looking through my apache configuration files and the only thing that stood out which doesn't make sense here is this:

LimitRequestFieldSize 8200
LimitRequestLine 8200

I say it doesn't make sense because I set the values to 8200 which I think means accept up to 8200 characters in the URL (not 400).

Is there a setting I can use in apache to fix this problem, because I know its an apache issue but I'm not sure which setting to fix.

Answer 1

Based on both your question as well as your follow up comments it would appear to me that the issue is to do with your rewrite rules not taking effect. You mention that the long string of numbers is a base64 encoded string of a large range of parameters, from this statement I make the assumption that the base 64 encoded string is not in fact a folder you are trying to access however from your final comment made Jan 1 at 0:45 you state

Apache claims I'm trying to access a folder with that length and the underlying file system (linux ext4) claims the name is too long)

From this comment it would indicate to me that Apache is not rewriting the URL so that the base64 encoded parameters are sent to a script to process and is instead treating it as a directory to access, in which case the string is in fact too long for a directory or file name in the ext4 filesystem. Take a look at your rewrite rules and make sure that the bbase64 encoded string is rewritten as a parameter to a script file.