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@CHIP-RTOS - Secure Shell

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SSH Server - Secure Shell

This documentation describes the SSH Server (Secure Shell) of the @CHIP-RTOS. The SSH Server is only available on the IPC@CHIP®s SC1x3/SC2x. The goal of SSH is to replace the earlier Telnet protocol, which did not provide strong authentication or guarantee confidentiality.


Features:
  • SSH-2 protocol
  • OpenSSH compatible key format
  • Password and public key user authentication
  • Local and Remote TCP Forwarding support
  • Cryptographic algorithms: Diffie-Hellman, RSA, DSA, AES, ARCFOUR, 3DES, MD5, SHA-1
  • Number of supported sessions (clients): 5
  • Number of supported channels per session: 10


Configuration:

By default the SSH server is enabled with a built-in RSA key. The fingerprint for this key is:
    ssh-rsa 1024 a4:26:0d:9b:ac:5f:71:da:9d:82:3a:60:9a:e8:2b:65
The default user name and password is: ssh
The user can configure the server with some SSH CHIP.INI entries.
For key generation we suggest to use PuTTY.

Create the server key for server authentication:

  • Open 'puttygen.exe'.
  • Select SSH-2 RSA or SSH-2 DSA from the parameters field.
    Note: The handshake with a DSA key is a bit faster.
  • Click the generate button.
  • Do not enter a passphrase. Server keys with passphrase are currently not supported.
  • Export the key in the OpenSSH format.
  • Transfer this key to the IPC@CHIP®.
  • Specify the key filename in the RSA_KEYFILE or the DSA_KEYFILE entry, depending on your previous choice what key algorithm to use for server authentication.

Create a user, password:

  • Specify a user name inside the USERx entry.
  • Specify a password inside the PASSWORDx entry.

Create key for user public key authentication:

  • Open 'puttygen.exe'.
  • Select SSH-2 RSA or SSH-2 DSA from the parameters field.
  • Click the generate button.
  • Save the private key.
  • Copy the text from the dialog 'Public key for pasting into OpenSSH authorized_keys file'.
  • Past the text into a new text file.
  • Get sure that there are no line breaks.
  • If you like you can add other keys to this file. Each key must be in his own line.
  • Transfer this file to the IPC@CHIP®.
  • Specify the filename in the USERx_KEYFILE entry.
  • Specify the private key filename inside your SSH client configuration.

Enable TCP Port Forwarding:

  • By default the port forwarding option is disabled.
  • You have to enable LOCAL_FORWARD, if you want to tunnel incomming TCP connections to a server located on the IPC@CHIP®.
  • You have to enable REMOTE_FORWARD, if you want to tunnel outgoing TCP connections to a server outside the IPC@CHIP®.


License Notes:

The @CHIP-RTOS SSH Server implementation was ported from the Dropbear source code. Dropbear comes with the following license:

Copyright (c) 2002-2004 Matt Johnston
Portions copyright (c) 2004 Mihnea Stoenescu
All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Key import code is modified from PuTTY's import.c, licensed as follows:

PuTTY is copyright 1997-2003 Simon Tatham.

Portions copyright Robert de Bath, Joris van Rantwijk, Delian Delchev, Andreas Schultz, Jeroen Massar, Wez Furlong, Nicolas Barry, Justin Bradford, and CORE SDI S.A.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.



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