Umbraco: disable front end for client

UmbracoDisableClientOnFrontEnd.cs

var userTicket = new System.Web.HttpContextWrapper(System.Web.HttpContext.Current).GetUmbracoAuthTicket();

if (!Request.Url.Host.Equals("localhost", StringComparison.OrdinalIgnoreCase))
{
    var user = userTicket?.Name
        .IfNotNullThen(()=>ApplicationContext?.Services?.UserService?.GetByUsername(userTicket.Name));
    if (user == null)
    {
        Response.Redirect("/umbraco", true);
    }
    else if (user.UserType.Alias.Equals("client",StringComparison.OrdinalIgnoreCase))
    {
        throw new UserAuthorizationException("User is not allowed to preview");
    }
}