TCP/IP Products

uSSH™ Secure Server
Overview
Portable ANSI C SSH SDK for interactive
shell and tunneled TCP/IP security layer.
Implement secure interactive shell and SSH
tunneled application functions using the
uSSH solution. Secure telnet replacement is
just the beginning. uSSH provides a flexible
TCP/IP security layer for existing and new
applications using the built-in command
dispatcher. Easy to integrate with run-time
environment using RTOS integration
features.
The uSSH SDK can be complied for a range
of processors and platforms, and comes
equipped with utilities and toolkits to manage
user accounts and private keys. Build
options include tailored asymmetric and
symmetric crypto suite, login banner, account
access control and other features. The
compact uSSH protocols and fully integrated
math and crypto library can be tailored to a
very compact memory footprint under 50K on
a typical Cortex-M3 flash MCU.
Interactive Shell Application
uSSH supports an interactive secure telnet
replacement as shown in the following
diagram, where shell communications are
encrypted in the SSH secure tunnel:

Figure 1: uSSH Interactive Shell
The shell session is initiated by the system
operator using a desktop command line or
GUI SSH terminal client such as openSSH,
Bitvise, teraterm, or putty. The interactive
session connects with uSSH Server on the
routed IP address and port over LAN or
WAN. Based on the default or explicit
session username, the operator is prompted
to enter a password. The password is sent
over the encrypted channel and verified by
the uSSH Server.
uSSH uses an embedded or file loaded
passwords file to authenticate the username
and password. The authenticated session is
handed off to the application’s embedded
shell that uses simple line oriented message
interface to interact with the user.
The uSSH command dispatcher includes
flexible support for multiple operator access
levels based on login user name. Read-only
system monitoring can be enabled for
technician level, while configuration changes
are restricted to administrator. Changes to
factory defaults or service affecting
configuration can be restricted at factory
access level.
General Purpose Secure Tunnel
uSSH can be used for a general purpose
security tunnel using the SSH exec protocol.
The exec request is processed by the uSSH
command dispatcher and handed off to the
application specific task. The task
communicates with a desktop or M2M endpoint
application, as illustrated in the
following diagram showing the encrypted
SSH tunnel:

Figure 2: End to End SSH Tunnel
The embedded task can be executed in-line
with the uSSH dispatcher, asynchronously, or
in a dedicated RTOS service task or thread.
uSSH is source code licensed, royalty-free,
and available on a range of platforms
including CM3, and integrated with leading
RTOS and tools including IAR and GCC.
Take advantage of the SSH security protocol
and accelerate your time to market with the
uSSH SDK.
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