Needed to be able to work with firewall rules on servers at work, so decided to start by getting the actual rule query and update part done, so I can add them to a more fleshed out script later.
#NetFirewallRule method for newer versions of Powershell
#Create a new test rule
New-NetFirewallRule -DisplayName "BLACKLIST_IN" -RemoteAddress 9.9.9.9 -Direction Inbound -Protocol TCP -LocalPort Any -Action Block
#Get the IP addresses in the current rule for the remote address field
$curIP = (Get-NetFirewallRule -DisplayName "BLACKLIST_IN" | Get-NetFirewallAddressFilter).RemoteAddress
#Define the new IP addresses to add, and then merge the lists
$newIPs = "9.9.9.10-9.9.9.11","9.9.9.14/31"
$addIPs = @($newIPs) + @($curIP)
#Set the rule with the new list
Set-NetFirewallRule -DisplayName "BLACKLIST_IN" -RemoteAddress $addIPs
Code language: PowerShell (powershell)#netsh version for older versions of Powershell
#Get the current rule and convert it from comma separated to a list
$netshout = netsh advfirewall firewall show rule name="BLACKLIST_IN"
$nshIP=($netshout | findstr RemoteIP).trim("RemoteIP: ").split(",")
#Define the new IP addresses to add, and then merge the lists
$newnshIPs = "9.9.9.13","9.9.9.14/31"
$nshaddIPs = @($nshIP) + @($newnshIPs)
#Take the new list and convert back to comma separated
$IPList = ($nshaddIPs | Select-Object) -join ","
#Set the rule with the new list
netsh advfirewall firewall set rule name ="BLACKLIST_IN" new remoteip=$IPList
Code language: PowerShell (powershell)