In the modern IT landscape, managing user sessions is critical. Whether it’s ensuring that unused sessions don’t consume resources or maintaining security protocols by ensuring that unauthorized sessions are terminated, there’s a need for efficient session management. This importance is emphasized when we consider the rise of remote working and the multiple sessions initiated from various locations. PowerShell, with its versatility, offers an excellent solution to this challenge through this script which will remotely log off users
Background
The provided script serves a simple yet crucial purpose: logging off specified user(s) from a Windows machine, with the exception of the console session. While many IT professionals and Managed Service Providers (MSPs) might wonder about its utility given the availability of GUI-based tools, remember that automated, scalable solutions often require script-based approaches. This script allows admins to seamlessly integrate user log off capabilities within larger automation workflows, crucial for enterprises with numerous user sessions to manage.
The Script
#Requires -Version 5.1
<#
.SYNOPSIS
Logs off user(s) specified. You can't log off a user from the console session.
.DESCRIPTION
Logs off user(s) specified. You can't log off a user from the console session.
.EXAMPLE
-User "Administrator"
Logs off Administrator user.
.EXAMPLE
-User "Administrator","Guest"
Logs off Administrator and Guest users.
.EXAMPLE
PS C:> Logoff-User.ps1 -User "Administrator","Guest"
Logs off Administrator and Guest users.
.OUTPUTS
String[]
.NOTES
Minimum OS Architecture Supported: Windows 10, Windows Server 2016
Release Notes:
Initial Release
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.COMPONENT
ManageUsers
#>
[CmdletBinding(SupportsShouldProcess = $True)]
param (
# User name(s) to log off
[Parameter(Mandatory = $true)]
[String[]]
$User
)
begin {
function Test-IsElevated {
$id = [System.Security.Principal.WindowsIdentity]::GetCurrent()
$p = New-Object System.Security.Principal.WindowsPrincipal($id)
if ($p.IsInRole([System.Security.Principal.WindowsBuiltInRole]::Administrator))
{ Write-Output $true }
else
{ Write-Output $false }
}
Function Get-QueryUser() {
Param()
# Replaces all occurrences of 2 or more spaces in a row with a single comma
$Lines = @(query.exe user).foreach({ $(($_) -replace ('s{2,}', ',')) })
$Header = $($Lines[0].split(',').trim())
for ($i = 1; $i -lt $($Lines.Count); $i++) {
$Line = $($Lines[$i].split(',')).foreach({ $_.trim().trim('>') })
# Accounts for disconnected users
if ($Line.count -eq 5) {
$Line = @($Line[0], "$($null)", $Line[1], $Line[2], $Line[3], $Line[4] )
}
$CurUser = [PSCustomObject]::new()
for ($j = 0; $j -lt $($Line.count); $j++) {
$CurUser | Add-Member -MemberType NoteProperty -Name $Header[$j] -Value $Line[$j]
}
$CurUser
}
}
}
process {
if (-not (Test-IsElevated)) {
Write-Error -Message "Access Denied. Please run with Administrator privileges."
exit 1
}
# Get a list of users logged on from query.exe, format it for powershell to process
$QueryResults = Get-QueryUser
# Accounts for only one user logged in
$QueryTest = $($QueryResults | Select-Object -First 1)
if (
$QueryResults.Count -or
(
$QueryTest.USERNAME -is [String] -and
-not [String]::IsNullOrEmpty($QueryTest.USERNAME) -and
-not [String]::IsNullOrWhiteSpace($QueryTest.USERNAME)
)
) {
$script:HasError = $false
$QueryResults | Where-Object {
# For each session filter out the user that weren't specified in $User
$_.UserName -in $User
} | ForEach-Object {
Write-Host "Found Logged In User: $($_.UserName)"
if ($_.SessionName -like "console") {
# We can't log out a user that is at the console.
# We could do this logic in the Where-Object code block, but then there isn't an output of what was skipped.
# https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/logoff#remarks
# "You can't log off a user from the console session."
Write-Host "Skipping user, can't log off a user($($_.UserName)) from the $($_.SessionName) session."
}
else {
# Log off the user session with a matching ID
logoff.exe $_.Id
if ($LASTEXITCODE -gt 0) {
$script:HasError = $true
Write-Error "logoff.exe $($_.Id) returned exit code: $LASTEXITCODE"
}
else {
Write-Host "Logged Off User: $($_.UserName)"
}
}
}
if ($script:HasError) {
exit 1
}
}
else {
Write-Output "No Users Logged In"
exit 2
}
}
end {}
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Detailed Breakdown
- Initialization: The script starts with a series of comments, or ‘.SYNOPSIS’, ‘.DESCRIPTION’, and ‘.EXAMPLE’, which provide an overview, detailed description, and usage examples, respectively.
- Parameters: The param block defines that the script requires an input ($User), which is the username(s) to log off.
- Functions: Two primary functions are defined:
- Test-IsElevated: Determines if the script is run with administrator privileges.
- Get-QueryUser: Fetches a list of logged-on users using the Windows command query.exe user, and then formats this output for easier consumption by PowerShell.
- Process Block: The main operations occur here:
- Permission Check: Checks if the script is running with administrative privileges using Test-IsElevated.
- Session Query: Retrieves all logged-on users via Get-QueryUser.
- Session Termination: Iterates through the list of logged-on users. If the username matches the provided $User parameter and is not a console session, it logs off that user using logoff.exe.
Potential Use Cases
Imagine a scenario where an IT admin for a large organization observes an unexpected surge in resource usage during off-hours. They identify multiple user sessions that have been left active and need to be terminated to free up resources. Instead of logging off users manually, our script could be deployed across multiple machines, swiftly terminating the unnecessary sessions.
Comparisons
Traditional methods like using Task Manager or the Windows GUI require manual effort and aren’t scalable across multiple machines. While there are third-party tools available, using native PowerShell ensures no additional software overhead and better compatibility.
FAQs
- Does the script terminate all sessions?
No, it logs off only the specified users and never the console session. - Can it run on any Windows machine?
It supports Windows 10 and Windows Server 2016 onwards.
Implications
Improper session management can lead to security vulnerabilities. Malicious entities can exploit active sessions to gain unauthorized access. By ensuring that only the necessary sessions remain active, the script contributes significantly to IT security.
Recommendations
- Always run the script with administrator privileges.
- Before executing in a live environment, test the script in a controlled setting to ensure it behaves as expected.
Final thoughts
When it comes to efficiently managing user sessions in a Windows environment, PowerShell provides robust and versatile solutions. This script showcases just a fragment of its capabilities. For those seeking an integrated platform to streamline such tasks, NinjaOne offers an encompassing suite of tools that seamlessly integrate with scripts like this, ensuring optimal IT infrastructure management.
