The ssh library was designed to be used by programmers needing a working SSH
implementation by the mean of a library. The complete control of the client is
made by the programmer. With libssh, you can remotely execute programs, transfer
files, use a secure and transparent tunnel for your remote programs.
With its Secure FTP implementation, you can play with remote files easily,
without third-party programs others than libcrypto (from openssl).

libssh features:

 * Full C library functions for manipulating a client-side SSH connection
 * SSH2 and SSH1 protocol compliant
 * Fully configurable sessions
 * Server support, SSH agent authentication support
 * Support for AES-128, AES-192, AES-256, Blowfish, 3DES in CBC mode
 * Use multiple SSH connections in a same process, at same time
 * Use multiple channels in the same connection
 * Thread safety when using different sessions at same time
 * POSIX-like SFTP implementation with openssh extension support
 * SCP implementation
 * RSA and DSS server public key supported
 * Compression support (with zlib)
 * Public key (RSA and DSS), password and keyboard-interactive authentication

WWW: http://www.libssh.org/