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Networking Protocol Software for Embedded Processors
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SSH Server : Frequently Asked Questions

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1:What is SSH?
According to Wikipedia:
Secure Shell, or SSH, is a cryptographic (encrypted) network protocol to allow remote login and other network services to operate securely over an unsecured network. It provides a secure channel over an unsecured network in a client-server architecture, connecting an SSH client application with an SSH server. Common applications include remote command-line login and remote command execution, but any network service can be secured with SSH.
InterNiche's SSH is designed specifically for the needs of embedded controllers and implements 'SSH-2'.
2:Is SSH the same as Secure Telnet?
No, though the most frequent usage of SSH is to run Telnet through a secure tunnel.
3:Is InterNiche's SSH Server interoperable with off-the-shelf Clients?
Absolutely. /usr/bin/ssh, PuTTY and OpenSSH Clients are frequently used with our SSH server
4:How does SSH provide a secure tunnel?
By internally 'looping back' traffic from the SSH-secured port to an application's regular communication port, the application is not even aware that its data is coming/through a secured connection.
5:Which specifications are supported by InterNiche's SSH Server?
The primary specifications implemented by InterNiche's SSH are:
  • SSH Protocol Architecture (RFC 4251)
  • SSH Authentication Protocol (RFC 4252)
  • SSH Transport Layer Protocol (RFC 4253)
  • SSH Connection Protocol (RFC 4254)
6:Does InterNiche's SSH work over both IPv4 and IPv6?
Yes. The SSH Server can tunnel IPv4 and IPv6 traffic simultaneously.
7:How many secure tunnels will InterNiche's SSH support?
In the terminology of SSH, a secure tunnel is called a 'channel'. The number of channels supported by the SSH Server is limited only by the amount of memory available in your embedded target.
8:How many applications can be run through an SSH tunnel?
The number of sessions that can be run through an SSH-secured channel is limited only by the amount of memory available in your embedded system.
9:Does InterNiche's SSH require a pre-emptive RTOS?
No. The SSH Server can run in a No-OS (SuperLoop), cooperative tasking or a pre-emptive RTOS environment.
10:What are the licensing terms of InterNiche's SSH?
Like all InterNiche protocol software, the SSH license includes pre-paid royalties, the amount of which depends upon whether you sign a Product, Platform or Architecture license. Details can be explained by
11:Is InterNiche's SSH covered by GPL?
No. InterNiche products are 'closed-source' and do not subject your own development efforts to GPL's requirement that you release your proprietary software to the public.
12:Can I use my hardware's encryption acceleration?
Yes. By providing the proper entry points to InterNiche's CryptoEngine™, SSH will use your device's encryption blocks when required.
13:Is there Technical Support available if I have questions or problems?
Yes. InterNiche source code products come with one year of Support, provided directly from our development engineers so you don't have to rely upon members of a 'user forum' for advise, assistance or modifications. And with a current Support Agreement, you can also look forward to being provided with any bug fixes released by InterNiche.
14:Is this code portable to non-InterNiche TCP/IP stacks?
Yes. Provided they include appropriate 'loop-back' support.
15:Does InterNiche's implementation also support PTY?
Yes. Remote Command Execution with PTY is supported.
16:What is the FLASH (code size) requirement for SSH?
Excluding the encryption code (much of which is available in hardware), the protocol implementation is approximately 33K bytes for PIC32 and Cortex architectures.
17:What microcontroller architectures are able to run SSH?
InterNiche's SSH Server should be able to run without modification on any 32bit controller capable of accessing data in 8bit bytes.
18:Does an application need to be modified to operate through SSH?
No. SSH will have to be configured to forward data to/from the application's chosen ports, but that is all.
19:Is SCP provided for securely copying files?
Yes, SCP is included.