Quite an ominous title for a post, but the reason for this post is when you’re on your iOS device and you navigate yourself to the software update section and you see a software update……
New iOS update - oh, boy, oh boy
Excitement, the placebo effect of a software update will be your phone will run smoother and it will run quicker and it won’t be as laggy - no, not really.
Where does your update come from?
The question here is not about the software update, The question here is where does it come from, your options are:
- Direct from Apple
- Via an Apple content caching server
- Via a proxy server
If you’re in a corporate environment, it is highly likely that you could be using a proxy server.
Do you not need an iOS device to check that?
No, you can quite easily craft a script that can run on Windows that will emulate being an iPhone to see what happens when it tries to request that software update.
I can check this on Windows platforms?
Yes, absolutely, however, the only caveat to that is if you do have a Apple content caching server then it must be accessible from the network you’re connecting from, if you have this behind an ACL or a firewall and it can’t talk to it, it will won’t be able to download updates from it.
What does the script look like when run?
This is what the script looks like when its run:
Script : iOSUpdaterQuery.ps1
# Script to detect Apple Content Caching servers and distinguish from regular proxies
function Test-AppleCacheServer {
param(
[string]$TestURL = "http://mesu.apple.com/assets/com_apple_MobileAsset_SoftwareUpdate/com_apple_MobileAsset_SoftwareUpdate.xml"
)
try {
Write-Host "Testing for Apple Content Cache service..." -ForegroundColor Cyan
# First check for Content Cache service registration
$contentCacheService = $null
try {
# Check if the Apple Content Cache service exists
$contentCacheService = Get-Service "AssetCache" -ErrorAction SilentlyContinue
if ($contentCacheService) {
Write-Host "Apple Content Cache service found on this machine!" -ForegroundColor Green
}
}
catch {
Write-Host "No local Content Cache service found" -ForegroundColor Yellow
}
# Make test request
$request = [System.Net.WebRequest]::Create($TestURL)
$request.Method = "GET"
$request.UserAgent = "AssetCache/1.0"
# Add headers that Apple devices use
$request.Headers.Add("X-Apple-Asset-Version", "2.0")
$request.Headers.Add("X-Apple-Client-Application", "Software Update")
Write-Host "`nSending test request..."
$startTime = Get-Date
$response = $request.GetResponse()
$responseTime = ((Get-Date) - $startTime).TotalMilliseconds
Write-Host "Response received in $responseTime ms"
# Analyze the response
$isAppleCache = $false
$isProxy = $false
$cacheHeaders = @()
$proxyHeaders = @()
Write-Host "`nAnalyzing response headers..."
foreach ($header in $response.Headers.AllKeys) {
$value = $response.Headers[$header]
Write-Host "$header : $value"
# Check for Apple Cache specific headers
switch ($header) {
"X-Apple-Cache-Session" {
$isAppleCache = $true
$cacheHeaders += "$header : $value"
}
"X-Apple-Cache" {
$isAppleCache = $true
$cacheHeaders += "$header : $value"
}
"X-Apple-Request-UUID" {
$isAppleCache = $true
$cacheHeaders += "$header : $value"
}
"Via" {
if ($value -match "squid|proxy|nginx") {
$isProxy = $true
$proxyHeaders += "$header : $value"
}
elseif ($value -match "AssetCache|apple-cache") {
$isAppleCache = $true
$cacheHeaders += "$header : $value"
}
}
"X-Cache" {
if ($value -match "AssetCache|apple-cache") {
$isAppleCache = $true
$cacheHeaders += "$header : $value"
}
else {
$isProxy = $true
$proxyHeaders += "$header : $value"
}
}
}
}
# Check response URI for local network
$responseUri = $response.ResponseUri
$responseIP = [System.Net.Dns]::GetHostAddresses($responseUri.Host)
$isLocalIP = $responseIP | Where-Object {
$ip = $_.IPAddressToString
$ip -match "^(10\.|172\.(1[6-9]|2[0-9]|3[0-1])\.|192\.168\.)"
}
# Output results
Write-Host "`nResults:" -ForegroundColor Cyan
if ($isAppleCache) {
Write-Host "Apple Content Cache server detected!" -ForegroundColor Green
Write-Host "`nCache indicators found:"
foreach ($header in $cacheHeaders) {
Write-Host "- $header"
}
if ($isLocalIP) {
Write-Host "Server is on local network: $($isLocalIP.IPAddressToString)"
}
}
elseif ($isProxy) {
Write-Host "Regular proxy server detected (not an Apple Content Cache)" -ForegroundColor Yellow
Write-Host "`nProxy indicators found:"
foreach ($header in $proxyHeaders) {
Write-Host "- $header"
}
}
else {
Write-Host "Direct connection to Apple servers (no cache or proxy detected)" -ForegroundColor Yellow
}
$response.Close()
}
catch {
Write-Error "Error during testing: $_"
Write-Host "Full error details: $($_.Exception.Message)"
}
}
# Run the test
Write-Host "Apple Content Cache Detection Tool`n" -ForegroundColor Cyan
Test-AppleCacheServer