Weird http request in access_log

Question

I'm seeing weird requests in my access_log

124.31.204.10 - - [24/Jan/2010:09:37:29 +0000] "CONNECT 205.188.251.43:443 HTTP/1.0" 500 10488 "-" "-"

None of those IP's are mine:
124.31.204.10 - this seems to be from china
205.188.251.43 - this one from US

Any ideas what this might be?

Answer 1

Yes, it's someone scanning servers to see if they can tunnel through them by using the CONNECT verb. It's failing (HTTP response code is 500), so it's nothing to worry about. You'll see lots of this with your web server open to the world.

124.31.204.10 is the client IP address, and 205.188.251.43 is the address the client wants your web server to tunnel to.