How can you check for existing firewall rules using Powershell

Question

So, I've got this script:

function Add-FirewallRule {
   param( 
      $name,
      $tcpPorts,
      $appName = $null,
      $serviceName = $null
   )
    $fw = New-Object -ComObject hnetcfg.fwpolicy2 
    $rule = New-Object -ComObject HNetCfg.FWRule

    $rule.Name = $name
    if ($appName -ne $null) { $rule.ApplicationName = $appName }
    if ($serviceName -ne $null) { $rule.serviceName = $serviceName }
    $rule.Protocol = 6 #NET_FW_IP_PROTOCOL_TCP
    $rule.LocalPorts = $tcpPorts
    $rule.Enabled = $true
    $rule.Grouping = "@firewallapi.dll,-23255"
    $rule.Profiles = 7 # all
    $rule.Action = 1 # NET_FW_ACTION_ALLOW
    $rule.EdgeTraversal = $false
    if(*here*)
    {
    $fw.Rules.Add($rule)
    }

}

and I want to be able to put something in the if() that will check and see if the rule already exists before it adds it. I'm not terribly familiar with powershell, so go easy on me :P

Answer 1

PowerShell Firewall example for SDL Microservices

Only create a new firewall rule if it does not already exist

$rules = Get-NetFirewallRule

$par = @{
    DisplayName = ""
    LocalPort = 80
    Direction="Inbound"
    Protocol ="TCP" 
    Action = "Allow"
}

$par.LocalPort = 8081
$par.DisplayName = "SDL Web 8 Stage Content Microservice on port $($par.LocalPort)"
if (-not $rules.DisplayName.Contains($par.DisplayName)) {New-NetFirewallRule @par}

$par.LocalPort = 8082
$par.DisplayName = "SDL Web 8 Stage Discovery Microservice on port $($par.LocalPort)"
if (-not $rules.DisplayName.Contains($par.DisplayName)) {New-NetFirewallRule @par"}