Blocking an IP Address
 

I have a spammer on my site, how do I block an IP address

What do you mean exactly - do you want to stop someone from posting a specific url?

i have a spammer who continues to sign up for a new account after each banning. Is there a way to stop this person by blocking their IP address, so not URL

In the adminCP settings under "User Banning Options", there's a setting to enter ip addresses that you want to ban.

Besides banning of ip's have you considered to use one of the many antispam mods at the mod section?

There are also mods out there that will allow you to ban his host so even if he did change his ip he won't change his host

Like this even know it is for spiders but it bans them from there host I use it all the time if I can't get rid of a pest member
https://vborg.vbsupport.ru/showthread.php?t=268208