ToggleProxy.ps1

param(
    [switch]$Enable,
    [switch]$Disable,
    $ProxyServer = "localhost",
    $ProxyPort = "8080"
)
$Path = "HKCU:\Software\Microsoft\Windows\CurrentVersion\Internet Settings"
$Proxy = "$($ProxyServer):$($ProxyPort)"

$ErrorActionPreference = "stop"





# This will happen automatically some time after the registry is updated, but we can call this DLL function to make it instant.
function Refresh-System
{
    $signature = @'
[DllImport("wininet.dll", SetLastError = true, CharSet=CharSet.Auto)]
public static extern bool InternetSetOption(IntPtr hInternet, int dwOption, IntPtr lpBuffer, int dwBufferLength);
'@

    $INTERNET_OPTION_SETTINGS_CHANGED   = 39
    $INTERNET_OPTION_REFRESH            = 37
    $type = Add-Type -MemberDefinition $signature -Name wininet -Namespace pinvoke -PassThru
    $a = $type::InternetSetOption(0, $INTERNET_OPTION_SETTINGS_CHANGED, 0, 0)
    $b = $type::InternetSetOption(0, $INTERNET_OPTION_REFRESH, 0, 0)
    return $a -and $b
}

function Get-ProxyEnabled
{
    Try
    {
        $Key = Get-ItemProperty -Path $Path -Name ProxyEnable
        return $Key.ProxyEnable -eq 1
    }
    Catch [System.Management.Automation.PSArgumentException]
    {
        # This handles the case where the registry key does not exist.
        return $False
    }
}

function Enable-Proxy
{
    Set-ItemProperty -Path $Path -Name ProxyEnable -Value 1         #Enable the explicit proxy
    Set-ItemProperty -Path $Path -Name ProxyServer -Value $Proxy    #Configure the server settings

    echo "Enabled proxy"
}

function Disable-Proxy
{
    Set-ItemProperty -Path $Path -Name ProxyEnable -Value 0         #Disable the explicit proxy
    Try
    {
        Remove-ItemProperty -Path $Path -Name ProxyServer               #Clear the server settings
    }
    Catch [System.Management.Automation.PSArgumentException]
    {
        # This handles the case where the registry key does not exist.
    }

    echo "Disabled proxy"
}





$ProxyEnabled = Get-ProxyEnabled

if ($Enable) {
    Enable-Proxy
} elseIf ($Disable) {
    Disable-Proxy
} elseIf ($ProxyEnabled) {
    Disable-Proxy
} else {
    Enable-Proxy
}

$RefreshSuccess = Refresh-System

if ($RefreshSuccess) {
    echo "Refreshed internet settings"
}