Hello all

I was wondering. Recently i have been getting warnings that an ip adress wants access through my firewall. I have 4 options to choose from : Deny once , Always deny , Allow once , Always allow. I think my brother was sick of the warnings and clicked "Always Allow". Now nothing weird has happened for over a week , but i'm getting a little paranoid that i might get hacked. Is there a way to "unallow" this/these ip adresses to get through my firewall once i allowed access? I use windows 7 and my firewall is always on. Someone please help me! Kind regards from Sven