Updated psd1 with min PS Version. Added example to README.

Merge for 0.4

README.md

@@ -27,3 +27,11 @@ Get Windows Firewall log on a remote computer using the Remote Registry service
 ```powershell
 Get-PSFirewallLog -LogProfile Public -ComputerName MyRemoteComputer -Verbose
 ```
+Get the last 100 events from the Domain profile of a remote machine, inferring the path using the local machine's path (doesn't use Remote Registry service):
+```powershell
+Get-PSFirewallLog -LogProfile Domain -ComputerName MyRemoteComputer -InferPath -Tail 100
+```
+Get the last 100 events from the Private profile firewall log and follow the log:
+```powershell
+Get-PSFirewallLog -LogProfile Private -Tail 100 -Wait
+```

public/Get-PSFirewallLog.ps1

@@ -1,4 +1,45 @@
 function Get-PSFirewallLog {
+    <#
+    .SYNOPSIS
+
+    Retrieves Windows Firewall log events and returns them as a table.
+
+    .DESCRIPTION
+
+    Retrieves Windows Firewall log events and returns them as a table. Log path can be directly specified or automatically determined based on local or remote registry settings.
+
+    .EXAMPLE
+
+    Get-PSFirewallLog -Path C:\Windows\system32\logfiles\firewall\pfirewall.log -Tail 1000
+
+    Get last 1000 Windows Firewall log lines at a specific path.
+
+    .EXAMPLE
+
+    Get-PSFirewallLog -LogDirectory C:\Windows\system32\logfiles\firewall\ -LogFileName domainfw.log
+
+    Get Windows Firewall log by specifying the log directory and filename separately.
+
+    .EXAMPLE
+
+    Get-PSFirewallLog -LogProfile Domain
+
+    Get Windows Firewall log by retrieving the path automatically from the registry on the local machine.
+
+    .EXAMPLE
+
+    Get-PSFirewallLog -LogProfile Public -ComputerName MyRemoteComputer -Verbose
+
+    Get Windows Firewall log on a remote computer using the Remote Registry service to get the log path.
+
+    .EXAMPLE
+
+    Get-PSFirewallLog -LogProfile Public -ComputerName MyRemoteComputer -InferPath
+
+    Get Windows Firewall log on a remote computer using the path configured in the local machine's registry (converted to a UNC path).
+    
+    #>
+
     [CmdletBinding(DefaultParameterSetName = 'direct')]
     param (
         # Path to firewall log. Defaults to $ENV:SystemRoot\system32\LogFiles\Firewall\pfirewall.log if parameter not supplied.
@@ -23,24 +64,39 @@ function Get-PSFirewallLog {
         [string]
         $LogProfile,
 
-        # Number of firewall events to retrieve. Defaults to 0 (All events).
+        # Number of firewall events to retrieve. Defaults to -1 (All events).
         [Parameter(Mandatory = $false)]
         [int]
-        $Tail = 0,
+        $Tail = -1,
 
         # ComputerName to retrieve log from
         [Parameter(Mandatory = $true, ParameterSetName = 'remote')]
         [string]
-        $ComputerName
+        $ComputerName,
+
+        # Follow the log
+        [Parameter(Mandatory = $false)]
+        [switch]
+        $Wait,
+
+        # Use local machine's registry setting to infer remote machine's log path
+        [Parameter(Mandatory = $false, ParameterSetName = 'remote')]
+        [switch]
+        $InferPath
     )
     
     begin {
         if($PSCmdlet.ParameterSetName -eq 'auto') {
-            # $Path = [Environment]::ExpandEnvironmentVariables((Get-ItemProperty -Path ("HKLM:\SOFTWARE\Policies\Microsoft\WindowsFirewall\{0}Profile\Logging" -f $LogProfile) -Name "LogFilePath").LogFilePath)
             $Path = Get-PSFirewallLogPath -LogProfile $LogProfile -Verbose:$VerbosePreference
         }
         elseif($PSCmdlet.ParameterSetName -eq 'remote') {
-            $Path = Get-PSFirewallLogPath -LogProfile $LogProfile -ComputerName $ComputerName -Verbose:$VerbosePreference
+            $lpc = "Get-PSFirewallLogPath -LogProfile $LogProfile -ComputerName $ComputerName"
+
+            if($InferPath) {
+                $lpc += " -InferPath"
+            }
+
+            $Path = Invoke-Expression $lpc -Verbose:$VerbosePreference
         }
     }
     
@@ -59,17 +115,6 @@ function Get-PSFirewallLog {
         }
 
         if(Test-Path $logPath) {
-            $log = Get-Content $logPath
-
-            if($log.Length -gt 0) {
-                # Remove header lines
-                $log = $log[5..($log.Length - 1)]
-
-                if($Tail -gt 0) {
-                    $startIndex = if($Tail -lt $log.Length) { $log.Length - $Tail } else { 0 }
-                    
-                    $log = $log[$startIndex..($log.Length - 1)]
-                }
 
             $members = @{
                 "Date" = 0
@@ -91,8 +136,24 @@ function Get-PSFirewallLog {
                 "Path" = 16
             }
 
-                $log | ForEach-Object {
+            $count = (Get-Content -Path $logPath).Count
+
+            # Check if outputting all events from the log and cut the first 5 lines that aren't events.
+            if(($Tail -lt 0) -or ($Tail -gt $count)) {
+                $Tail = $count - 5
+            }
+
+            Write-Verbose "Log has $count lines. Retrieving $Tail lines."
+
+            $c = "Get-Content -Path $logPath -Tail $Tail"
+
+            if($Wait) {
+                $c = "$c -Wait"
+            }
+
+            Invoke-Expression $c | ForEach-Object {
                 $line = $_
+
                 $split = $line -split ('\s')
 
                 $fwEvent = New-Object PSCustomObject
@@ -106,10 +167,6 @@ function Get-PSFirewallLog {
                 $fwEvent
             }
         }
-            else {
-                Write-Error "File $logPath has zero length."
-            }
-        }
         else {
             Write-Error "Failed to retrieve log at $logPath."
         }

public/Get-PSFirewallLogPath.ps1

@@ -1,4 +1,33 @@
 function Get-PSFirewallLogPath {
+    <#
+    .SYNOPSIS
+
+    Retrieves Windows Firewall log path for a given Profile.
+
+    .DESCRIPTION
+
+    Retrieves Windows Firewall log path for a local or remote machine for given Profile.
+
+    .EXAMPLE
+
+    Get-PSFirewallLogPath -LogProfile Domain
+
+    Retrieves path of the specified profile's log from the local machine.
+
+    .EXAMPLE
+
+    Get-PSFirewallLogPath -LogProfile Private -ComputerName MyRemoteComputer
+
+    Retrieves path of the specified profile's log from a remote machine using the Remote Regsitry service.
+
+    .EXAMPLE
+
+    Get-PSFirewallLogPath -LogProfile Domain -ComputerName MyRemoteComputer -InferPath
+
+    Retrieves path of the specified profile's log from a remote machine using registry settings configured on the local machine.
+
+    #>
+
     param(
         # Log Profile to retrieve path for
         [Parameter(Mandatory = $true)]
@@ -9,13 +38,29 @@ function Get-PSFirewallLogPath {
         # Remote Host to retrieve from
         [Parameter(Mandatory = $false, ParameterSetName = 'remote')]
         [string]
-        $ComputerName
+        $ComputerName,
+
+        # Use local machine's registry setting to infer remote machine's log path
+        [Parameter(Mandatory = $false, ParameterSetName = 'remote')]
+        [switch]
+        $InferPath
     )
 
     process {
-        $serviceName = "RemoteRegistry"
-
         if($PSCmdlet.ParameterSetName -eq 'remote') {
+
+            if($InferPath) {
+                # Get local registry key entry
+                $localPath = [Environment]::ExpandEnvironmentVariables((Get-ItemProperty -Path ("HKLM:\SOFTWARE\Policies\Microsoft\WindowsFirewall\{0}Profile\Logging" -f $LogProfile) -Name "LogFilePath").LogFilePath)
+
+                if($null -eq $localPath) {
+                    $defaultPath = "$ENV:SystemRoot\system32\LogFiles\Firewall\pfirewall.log"
+                    Write-Warning "Path for $LogProfile firewall log not defined in registry. Assuming default path of $defaultPath"
+                    $localPath = $defaultPath
+                }
+            }
+            else {
+                $serviceName = "RemoteRegistry"
                 $startTypeChanged = $false
                 $statusChanged = $false
 
@@ -61,7 +106,7 @@ function Get-PSFirewallLogPath {
                 if($statusChanged) {
                     Write-Verbose ("Reverting status of $serviceName Service to {0}." -f $remoteRegistry.Status)
                     # Set-Service -Name $serviceName -ComputerName $ComputerName -Status $remoteRegistry.Status
-                # Need to use Invoke-Command as Set-Service won't stop a service that has dependancies
+                    # Need to use Invoke-Command as Set-Service won't stop a service that has dependencies
                     Invoke-Command -ComputerName $ComputerName -ScriptBlock { Stop-Service -Name "RemoteRegistry" }
                     
                     # Verify that service has been restored to its original state.
@@ -80,6 +125,7 @@ function Get-PSFirewallLogPath {
                         Write-Warning "Failed to revert startup type of $serviceName to $($remoteRegistry.StartType)!"
                     }
                 }
+            }
 
             # Do the conversion to UNC path
             $path = "\\$ComputerName\" + $localPath.replace(':', '$')
@@ -91,7 +137,9 @@ function Get-PSFirewallLogPath {
             $path = [Environment]::ExpandEnvironmentVariables((Get-ItemProperty -Path ("HKLM:\SOFTWARE\Policies\Microsoft\WindowsFirewall\{0}Profile\Logging" -f $LogProfile) -Name "LogFilePath").LogFilePath)
 
             if($null -eq $path) {
-                $path = "$ENV:SystemRoot\system32\LogFiles\Firewall\pfirewall.log"
+                $defaultPath = "$ENV:SystemRoot\system32\LogFiles\Firewall\pfirewall.log"
+                Write-Warning "Path for $LogProfile firewall log not defined in registry. Assuming default path of $defaultPath"
+                $path = $defaultPath
             }
 
             return $path