The Simple Mail Transfer Protocol (SMTP) is a "Host-to-Host Protocol for the transmission of messages. It is used primarily for sending e-mails, and is used in practically any email client. In embedded systems, it is mainly used to regularly send a system status, or an ad hoc report errors.

The SEVENSTAX SMTP includes the SMTP stack and embedded mail user agent (MUA), which controls the sending process.According to RFC 2821 SMTP works over TCP on port 25.

Sending is possible with or without authentication. The authentication is the process:

  • SMTP after POP 

  • SMTP Auth. according to RFC 2554

be carried out.

The usual way, the SMTP can transmit only ASCII text. In combination with the SEVENSTAX MIME module, other content can be transferred.


The Post Office Protocol (POP) is a protocol for retrieving e-mails from an e-mail server. In version 3 (RFC 1081, POP3) it is a protocol utilized a global standard for querying e-mails. The simplicity and widespread use makes the protocol for embedded systems interesting. Embedded systems are to load regular data, and configurations from a server that can send e-mails so to be an alternative to a custom server architecture.

The SEVENSTAX POP3 includes the POP stack in version 3 and an embedded mail user agent (MUA), which controls the receiving process. According to RFC 1939, works with the POP3 module via TCP port 110 and can communicate with standard mail servers.

Authentication takes place either via plain text Auth. or MD5, and APOP. The received data is analyzed via streaming parser and passed to the application. In combination with the module SEVENSTAX MIME attachments can not be detected (attachments) and will be evaluated ASCII content.


The Telecommunication Network Protocol (Telnet) is a bi-directional byte-oriented network protocol. It is used to realize a simple data exchange between two participants, and uses TCP for data transfer. Compared to a pure TCP / IP socket, connections are replaced in addition to the Telnet connection-specific options and take into account the different requirements of heterogeneous networks.

Telnet clients are an integral part of a virtually all operating systems,
i.e. telnet can be used at any time without installation.

The SEVENSTAX telnet server is a implementation in accordance with RFC 854 / RFC 855 and supports TELNET sessions on TCP port 23 The port can be changed optionally.
The following TELNET options are supported:

  •   1 - Echo (RFC 857)

  •   3 - Suppress Go Ahead (RFC 858)

  •  31 - Negotiate About Window Size (RFC 1073)

Other options can be added by the application.
The SEVENSTAX Telnet Server is fully compatible with commercial telnet client for Windows, Unix, Linux and Apple.

Particularly powerful of SEVENSTAX Telnet Server through the use of SEVENSTAX NVT (Network Virtual Terminal). Using the NVT is the Telnet server is a powerful development and configuration tools.


The Network Virtual Terminal (NVT) is a character-terminal to input and output of data and commands. It uses a conventional manner in conjunction with the Telnet protocol, and serves as a virtual device between the two sides of the telnet session (client and server). In embedded systems, the NVT in combination with the built-in shell can be effectively leveraged to retrieve status information and configuration. Through its resource-saving operation, it can also be used in small systems.

The SEVENSTAX NVT is corresponding to RFC854 and includes an editor and an embedded shell with command functions. The SEVENSTAX NVT works sign and line-oriented, takes over the keyboard input from a port or a protocol and returns the required screen output. The input and output interface of the NVT can be connected with SEVENSTAX telnet server, the XMPP client associated with a driver or a serial interface.
The editor supports the "Backspace" - and the arrow keys and can work with and without echo. Inputs are captured in a simple history and can be retrieved.
The embedded shell provides the following functionality:

  • Start message with the device name and version 

  • Log on name and password 

  • Output of a log-strings and a prompt string 

  • controllable echo function 

  • standard integrated command 

  • generic interface to expand the command

When you login, the password input is hidden.