HeadlessChrome

[keyplyr]

UA: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/61.0.3163.79 Safari/537.36
Protocol: HTTP/1.1
Robots.txt: No
Host: Various

Headless Chrome is shipping in Chrome 59... A headless browser is a great tool for automated testing and server environments where you don't need a visible UI shell.

[developers.google.com...]

[lucy24]

a great tool for automated testing

Sounds like a job for

USER_AGENT suchandsuch
REMOTE_IP !my-own-IP
RewriteRule blahblah [F]

As it were.

[keyplyr]

Got caught in my UA filters because of the Headless
(a common ad blocker browser extension)