How we can save our pc and network with ransomeware like wanna cry and petya?

Look Sir if you want to save your network with ransomwhare (Wanna cry) then, first you need to know how it work.
and as my analyses it effect our network by using some port like samba/smb... And you need to just put the down/block you port of 445 and 139.
that it for save our network from wanna cry attach.
and please let me if you get ans about how to save our network from petya...
ithelp.arvind@gmail.com