REMOTE_ADDR and IPv6 in PHP

问题:

Is it safe to assume that $_SERVER['REMOTE_ADDR'] always returns a IPv4 address?

Thanks!

回答1:

The REMOTE_ADDR key is set by the web server, not PHP. If the web server listens on v6 and the user connects that way, it'll be a v6 address

回答2:

I have seen a bad IP address reported to php in REMOTE_ADDR from Apache 2.

It was '183.60..244.37'.

So the answer to your question, "Is it safe to assume...", I think is definitely no, REMOTE_ADDR can not be trusted.

As far as I know it is reported to PHP from the server, in my case Apache. Why it was bad I am still trying to figure out. I do know this. It came in as part of a batch of attack requests. Sometimes it was 183.60.244.37 and sometimes it was 183.60..244.37.

See also this.