//Servidor
while (protocolSI.GetCmdType() != ProtocolSICmdType.EOT)
            {
                networkStream.Read(protocolSI.Buffer, 0, protocolSI.Buffer.Length);
if (protocolSI.GetCmdType() == ProtocolSICmdType.USER_OPTION_2)
                {
                    string usernamestring = null;
                    string pass = null;

                    usernamestring = protocolSI.GetStringFromData();

                    Console.WriteLine("Attempt to login from" + usernamestring);

                    networkStream.Read(protocolSI.Buffer, 0, protocolSI.Buffer.Length);
                    if (protocolSI.GetCmdType() == ProtocolSICmdType.DATA)
                    {
                        pass = protocolSI.GetStringFromData();
                    }

                    IsClientLoggeIn = logReg.VerifyLogin(usernamestring, pass);
                }
}

//cliente

            ProtocolSI protocolSI = new ProtocolSI();

            string username = textBoxUsername.Text;

            string password = textBoxPassword.Text;

            byte[] userpacket = protocolSI.Make(ProtocolSICmdType.USER_OPTION_2, username);
            networkStream.Write(userpacket, 0, userpacket.Length);

            byte[] passpacket = protocolSI.Make(ProtocolSICmdType.DATA, password);
            networkStream.Write(passpacket, 0, passpacket.Length);