How can I tell if the connection is metered?

Question

I wrote a program that monitors an IMAP email account. It runs on a schedule, on a laptop that I travel with. Sometimes it runs when my internet connection is through my mobile device, which has a metered connection (that is, I pay by the GB), and I don't want it to, because it uses a lot of bandwidth, and it can wait until bandwidth is free.

So the question is: how can a .NET program determine when the connection its using is metered?

Fatuous

Is this Windows 8? I think Windows 8 has an 'is metered' property you can set on connections but I've not seen it on 7 or earlier. – Thereabouts

I would be very surprised if this is possible to do, given an arbitrary network connection. – Operable

@Rup: This is not a windows business. Unlike it contacts ISP and asks for link type. – Adrianadriana

@Adrianadriana but Windows knows if it's using wifi or if it's using a USB modem, and that's what he's asking. Why would it need to ask the ISP? – Thereabouts

@Rup: He is asking to not use bandwidth when it is costly i.e. when connecting via cell phone. – Adrianadriana

@xaqron Sure, and his cell phone will appear to Windows as a USB modem won't it? So I think that Windows can identify when it is routing packets through his cell phone and know that's expensive, whereas you think it can't do that without asking his ISP? – Thereabouts

@Rup: This is gonna turn to a chat. Also there are DSL modems plug by USB. You cannot rely on this. A USB modem i.e. for DSL line still can connect you to an unmetered link. Using RJ-45, USB, WiFi, Bluetooth... doesn't tell you about link financial plan. That's how ISP charge you according to your contract. A 3G operator may provide metered and unmetered plans at the same time so you cannot conclude connecting via SIM card always result in metered bandwidth. – Adrianadriana

I wouldn't have thought this was so complicated. In Windows 8, you can manually designate that a connection is metered. That flag must be stored somewhere, and read either via API or maybe a direct registry read. I'm not trying to build a usage heuristic or anything, just read the manual setting. – Fatuous

Windows 8.1 seems to detect this automatically when connecting to a phone. Outlook says it will work offline because of it. – Willemstad

Answer 1

A brief search of MSDN found the NetworkInformation.GetInternetConnectionProfile function. It looks like it's officially part of the Metro interface, but I have heard that desktop applications can access most of the Metro libraries.

Naseby

Answer 2

In 2021 you can use the powershell .NET framework and a registery KEY like that to test if your ethernet connection is set to metered:

$definition = @"
using System;
using System.Runtime.InteropServices;

namespace Win32Api
{

    public class NtDll
    {
        [DllImport("ntdll.dll", EntryPoint="RtlAdjustPrivilege")]
        public static extern int RtlAdjustPrivilege(ulong Privilege, bool Enable, bool CurrentThread, ref bool Enabled);
    }
}
"@

Add-Type -TypeDefinition $definition -PassThru | Out-Null
[Win32Api.NtDll]::RtlAdjustPrivilege(9, $true, $false, [ref]$false) | Out-Null

#Setting ownership to Administrators
$key = [Microsoft.Win32.Registry]::LocalMachine.OpenSubKey("SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkList\DefaultMediaCost",[Microsoft.Win32.RegistryKeyPermissionCheck]::ReadWriteSubTree,[System.Security.AccessControl.RegistryRights]::takeownership)
$acl = $key.GetAccessControl()
# Use your account "Administrators" or any other which is actually an existing one on your account
$acl.SetOwner([System.Security.Principal.NTAccount]"Administrators")
$key.SetAccessControl($acl)

#Giving Administrators full control to the key
$rule = New-Object System.Security.AccessControl.RegistryAccessRule ([System.Security.Principal.NTAccount]"Administrators","FullControl","Allow")
$acl.SetAccessRule($rule)
$key.SetAccessControl($acl)
$path = "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkList\DefaultMediaCost"
# you can check for "Ethernet" "Wifi" "4G" etc.
$name = "Ethernet"
#If the Value is 2 = metered
New-ItemProperty -Path $path -Name $name -Value "2" -PropertyType DWORD -Force | Out-Null

If you get the following error:

Exception calling "SetAccessRule" with "1" argument(s): "Some or all identity references could not be translated.".

Try to change the "Administrators" user to any other on your account which exists and has admin rights.

Sturmabteilung

Hmm, congrats on finding a solution but I don't like the idea of having to change registry permissions. There must be another way to find this. – Thereabouts

Answer 3

A three-liner from github. I added a line.

[void][Windows.Networking.Connectivity.NetworkInformation, Windows, ContentType = WindowsRuntime]
$cost = [Windows.Networking.Connectivity.NetworkInformation]::
  GetInternetConnectionProfile().GetConnectionCost()
$metered = $cost.ApproachingDataLimit -or $cost.OverDataLimit -or $cost.Roaming -or
  $cost.BackgroundDataUsageRestricted -or ($cost.NetworkCostType -ne
  "Unrestricted")
[pscustomobject]@{Metered=$metered}

Metered
-------
  False

Castellatus