Protocol Host showing in our Error Log / 404 Errors

Question

I'm getting an error showing up in my error logs over and over. I see it in an error log in cpanel as well as in an AW stats report.

The errors look like this:

/my_directory/'%20+%20protocol_host%20+%20'/images/greenthumb.png
/my_directory/'%20+%20protocol_host%20+%20'/images/imgsicon.png

I'm seeing this thousands of times a day.

the legit path in the example above would be something like this:

/my_directory/page.php?id=123454
(i.e www.my_site.com/my_directory/page.php?id=123454)

Any ideas what this protocol_host is referring to and why it would be hitting my error log so often?

My research before posting this question led me to something related to the search indexer on a windows operating system computer, but I can't see the connection.

Thanks in advance as always

Answer 1

I'm with @Shal. Although google gives you some results for 'protocol_host' I don't think that they are related to your problem. I guess it is either an error in your PHP code which generates the links or an erroneous client (or a hacker) is accessing your site

Answer 2

Looking at the error-URLs, it seems like the paths to some images are generated dynamically by concatenating strings; but the quotes are note set correctly.

/my_directory/'%20+%20protocol_host%20+%20'/images/greenthumb.png
without URL encoding is
/my_directory/' + protocol_host + '/images/greenthumb.png

PHP uses . to concatenate strings, but here a + is used. So I would guess that some JavaScript code causes this error.

Check your JS resources!

Answer 3

I would guess, that you are linking some resources relatively without a leading slash.

example:

<img src="images/foo.png" />

usually this leads to urls like http://example.com/images/foo.png instead of http://example.com/my_project/images/foo.png but can have other conseques as well.

This is just a guess though.