Auto enable ToS/DSCP setting in the Registry in C#

//Check for registry keys
RegistryKey rkToS = Registry.LocalMachine.OpenSubKey("SYSTEM\\CurrentControlSet\\Services\\TcpIp\\Parameters", true);
// If the return value is null, the key doesn't exist
if (rkToS == null)
{
    // The key doesn't exist; create it
    rkToS = Registry.LocalMachine.CreateSubKey("SYSTEM\\CurrentControlSet\\Services\\TcpIp\\Parameters");
}
// Attempt to retrieve the value for DisableUserTOSSetting; if null returned, the value doesn't exist in the registry.
if (rkToS.GetValue("DisableUserTOSSetting") != null)
{
    // The value exists; 
    int checkToSKey = (int)rkToS.GetValue("DisableUserTOSSetting");
    //Check if it has the right value
    if (checkToSKey != 0)
    {
        //Wrong value...correcting it
        rkToS.SetValue("DisableUserTOSSetting", 0);
        MessageBox.Show("I have just changed the Registry Key to enable ToS values.\nFor this to take effect, you need to restart your computer!");
        return;
    }
}
else
{
    //add value
    rkToS.SetValue("DisableUserTOSSetting", 0);
    MessageBox.Show("I have just added the Registry Key to enable ToS values.\nFor this to take effect, you need to restart your computer!");
    return;
}

How to change ToS or DSCP values in IP header while sending a Ping, in Microsoft Windows products?

By default, if you use the following command: “ping -v 8”, it would not change the ToS/DSCP value in the IP header in the ICMP Packet, even though you get no errors.

To enable this in windows, follow the steps below:

1. Open regedit
2. Go to the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\TcpIp\Parameters
3. If you are running Windows XP or Windows Server 2003, follow these steps:
   1. On the Edit menu, point to New, and then click DWORD Value.
   2. Type DisableUserTOSSetting as the entry name, and then press ENTER. (When you add this entry, the value is set to 0 (zero). Do not change the value.)
4. Quit Registry Editor, and then restart the computer.
5. After restarting the computer, in command prompt, type “ping <ip address> -v 8”, while taking a wired capture. You would see the DSCP value changed.

For more information, please refer to:

http://support.microsoft.com/kb/248611

http://technet.microsoft.com/en-us/library/cc739819.aspx