Blocking user registration without hostname

[ldkaplan]

Hi folks.

I've done a bit of searching but haven't found anything for this.

We have a disgruntled banned user that has been creating users with spoofed IP addresses. I'm not quite sure how he's doing it, but all of the IPs are lacking hostnames. I would think hostname would be there for any valid user.

Is there a way to block registration if the request has no hostname? Not sure if there is a mod in existence that does that.

If there isn't, can I modify one of php files to do that?

Also, can anyone think of a valid reason why a typical user would not have a hostname?

Thanks in advance.

[Marco van Herwaarden]

If there is a hostname (or just a duplicate of the IP used as host) depends on the ISP used.