ultimatepp/uppsrc/Core/SSH

SSH package for U++
--------------------
SSH package is a flexible and easy-to-use libssh2 wrapper for Ultimate++.
It supports both console and GUI-based applications on POSIX-compliant operating systems and
MS Windows (tm).

Classes:
--------------------

- Base (core) class  -> Ssh
  - Ssh session        -----> SshSession
  - Sftp subsystem     -----> SFtp
  - Ssh channel        -----> SshChannel
      - Scp channel                 -----> Scp
      - Exec channel                -----> SshExec
      - Real-time interactive shell -----> SshShell
      - X11 forwarding              -----> SshShell (as operation mode)      
      - Tcp/IP and port forwarding  -----> SshTunnel

- Known hosts manager -> SshHosts

Features and Highlights:
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- Ssh-derived classes have pick semantics, based on RAII principle, support RTTI, and allow
  polymorphism (i.e. different classes can be stored in the same arrays, etc.) through a common
  interface. 
- Uses U++ memory allocators (Native allocators is also a compile-time option)
- Uses OpenSSL by default. 
- Supports 3rd-party network proxies.
- Supports known hosts verification mechanism.
- Supports password, public key, host-based, and keyboard-interactive authentication methods.
- Supports ssh-agents.
- Supports real-time interactive command line (shell) interface with both console and GUI integration
  (works on both Windows and Posix-compliant OS'es)
- Supports multiple X11 connection forwarding.
- Supports Tcp/IP and port forwarding.
- Supports detailed (full) debug logging.

Todo:
--------------------

- Improve documentation.

Reference examples:
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- SshBasics: Demonstrates basic capabilities of SSH package.
- SFtpGUI:   Demonstrates a simple sftp browser with GUI.