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I don't know if this falls under server fault. We have HEAD requests disabled on our server. But we see thousands of HEAD requests, always with the same user agent. 'X11; Linux x86_64 chrome. It looks like an Ubuntu or other Linux machine. Have you ever seen a linux browser/Firefox make such a request? And why would that particular browser be different from the windows equivalent?

It looks like the technique used is HTTP pipelining.

Example user-agent:

Mozilla/5.0 (X11; Linux i686 on x86_64; rv:10.0) Gecko/20100101 Firefox/10.0

user42701
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  • I just looked and we've had ~3500 HEAD requests in the last 15 mins from all sorts of user agents... – Zypher Dec 19 '14 at 22:11

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You should not be disabling HEAD — HEAD is a compulsory part of HTTP, and a client is allowed to use HEAD whenever it desires.

I suspect that your Linux user is using the Polipo proxy, which performs aggressive pipelining and will use the HEAD request if the server doesn't properly implement If-Modified-Since conditional requests. Please implement HEAD in your server, otherwise you'll be locking out all users of Polipo.

(There are other reasons why a client might decide to use HEAD. For example, some versions of Mozilla/Firefox will query the server using HEAD when the user requests a download, so that they can present a confirmation dialog if the download is large.)

jch
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