Using PowerShell to programmatically configure Internet Explorer proxy settings to work before it has been opened

I came to the same result as Richard's (slightly shorter) whilst setting proxy for Server Core 2016. Horrific that this is necessary!

function Set-Proxy($proxy, $bypassUrls){    $proxyBytes = [system.Text.Encoding]::ASCII.GetBytes($proxy)    $bypassBytes = [system.Text.Encoding]::ASCII.GetBytes($bypassUrls)    $defaultConnectionSettings = [byte[]]@(@(70,0,0,0,0,0,0,0,11,0,0,0,$proxyBytes.Length,0,0,0)+$proxyBytes+@($bypassBytes.Length,0,0,0)+$bypassBytes+ @(1..36 | % {0}))    $registryPath = "HKCU:\Software\Microsoft\Windows\CurrentVersion\Internet Settings"    Set-ItemProperty -Path $registryPath -Name ProxyServer -Value $proxy    Set-ItemProperty -Path $registryPath -Name ProxyEnable -Value 1    Set-ItemProperty -Path "$registryPath\Connections" -Name DefaultConnectionSettings -Value $defaultConnectionSettings    netsh winhttp set proxy $proxy bypass-list=$bypassUrls}Set-Proxy "someproxy:1234" "*.example.com;<local>"

I figured it out.

The key part missing was a hex byte to indicate the length of the proxy address.

So I changed the line that concatinates the hex string to this:

$regString="46,00,00,00,00,00,00,00,0b,00,00,00,"+(%{[System.Convert]::ToString($proxy.length,16)})+",00,00,00," + $proxystring + (%{[System.Convert]::ToString($bypassList.length,16)}) + ",00,00,00," + $bypassString +  "00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00"

And that works successfully.

So for a belt and braces approach:netsh

netsh winhttp set proxy $proxy bypass-list=$bypassList

Internet explorer for system accounts:

foreach ($account in "LOCALSYSTEM","NETWORKSERVICE","LOCALSERVICE") {    & C:\windows\System32\bitsadmin.exe /Util /SetIEProxy $account Manual_proxy $proxy $bypassList}

Internet explorer for current accounts:

$proxyString = ""for ($i = 0;$i -lt (([System.Text.Encoding]::Unicode.GetBytes($proxy)).length); $i++) {    if ($i % 2 -eq 0) {        $byte = (([System.Text.Encoding]::Unicode.GetBytes($proxy))[$i])        $convertedByte=%{[System.Convert]::ToString($byte,16)}        $proxyString = $proxystring + $convertedByte  + ","    }}$bypassString = ""for ($i = 0;$i -lt (([System.Text.Encoding]::Unicode.GetBytes($bypassList)).length); $i++) {    if ($i % 2 -eq 0) {        $byte = (([System.Text.Encoding]::Unicode.GetBytes($bypassList))[$i])        $convertedByte=%{[System.Convert]::ToString($byte,16)}        $bypassString = $bypassString + $convertedByte  + ","    }}$regString="46,00,00,00,00,00,00,00,0b,00,00,00,"+(%{[System.Convert]::ToString($proxy.length,16)})+",00,00,00," + $proxystring + (%{[System.Convert]::ToString($bypassList.length,16)}) + ",00,00,00," + $bypassString +  "00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00"$regstringAsArray = ("0x"+$regString.replace(",",",0x")).Split(",")$reg = "HKCU:\Software\Microsoft\Windows\CurrentVersion\Internet Settings"Set-ItemProperty -Path $reg -Name ProxyServer -Value $proxySet-ItemProperty -Path $reg -Name ProxyEnable -Value 1Set-ItemProperty -Path $reg -Name ProxyOverride -Value $bypassList$reg = "HKCU:\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections"Set-ItemProperty -Path $reg -Name DefaultConnectionSettings -Type Binary -Value $regstringAsArraySet-ItemProperty -Path $reg -Name SavedLegacySettings -Type Binary -Value $regstringAsArray