Abstractions.Windows.Security.RemoveAccRuleFromUnknownUser C# (CSharp) Метод

        public static Boolean RemoveAccRuleFromUnknownUser(string dir)
        {
            DirectoryInfo dInfo = new DirectoryInfo(dir);
            DirectorySecurity dSecurity = dInfo.GetAccessControl();

            try
            {
                foreach (FileSystemAccessRule user in dSecurity.GetAccessRules(true, true, typeof(System.Security.Principal.NTAccount)))
                {
                    //LibraryLogging.Debug("directory ACE user: {0}", user.IdentityReference.Value);
                    if (user.IdentityReference.Value.StartsWith("S-1-5-21-"))
                    {
                        LibraryLogging.Debug("delete unknown directory ACE from {0} in {1}", user.IdentityReference.Value, dir);
                        dSecurity.RemoveAccessRule(user);
                    }
                }
            }
            catch (Exception ex)
            {
                LibraryLogging.Error("unable to RemoveAccRuleFromUnknownUser for {0} error {1}", dir, ex.Message);
                return false;
            }

            return true;
        }