Requests for images

with no referrer

[coyote]

I've noticed a dramatic increase in requests for images with no referrer. I have UAs of grabbers/downloaders blocked, though the requests are being made by common browser/os types. I also have anti-hotlinking measures in place and SE image bots blocked (vscooter, etc.).

So what could this be?

[WebJoe]

Someone with a desktop firewall that blocks referers?

[coyote]

Someone with a desktop firewall that blocks referers?

Does that apply to images not anchor linked, only called with

img

?
I thought things like Norton replaced the referrer URI with "++++++++++".

[WebJoe]

I used to have a desktop firewall running that blocked or replaced with any value all referers, no matter how the file was linked (href, src...)