ssh2-python 0.5.3rc1

Super fast SSH library - bindings for libssh2

Super fast SSH2 protocol library. ssh2-python provides Python bindings for libssh2.

Installation

System packages are available on the latest releases page built on Centos/RedHat 6/7, Ubuntu 14.04/16.04, Debian 7/8 and Fedora 22/23/24.

The library has no dependencies other than libssh2.

Installation from Source

Install libssh2 and Python header files.

Ubuntu

apt-get install libssh2-1-dev python-dev
pip install ssh2-python

RedHat

yum install libssh2-devel python-devel
pip install ssh2-python

API Feature Set

Currently the vast majority of the libssh2 API has been implemented with only few exceptions.

Complete example scripts for various operations can be found in the examples directory.

In addition, as ssh2-python is a thin wrapper of libssh2 with Python semantics, its code examples can be ported straight over to Python with only minimal changes.

Quick Start

Both byte and unicode strings are accepted as arguments and encoded appropriately. To change default encoding, utf-8, change the value of ssh2.utils.ENCODING. Channel output is always byte strings.

See Complete Example for a complete example including socket connect.

Please use either the issue tracker for reporting issues with code or the mail group for discussion and questions.

Contributions are most welcome!

Authentication Methods

Connect and get available authentication methods.

from __future__ import print_function

from ssh2.session import Session

sock = <create and connect socket>

session = Session()
session.handshake(sock)
print(session.userauth_list())

['publickey', 'password', 'keyboard-interactive']

Agent Authentication

session.agent_auth(user)

Command Execution

channel = session.open_session()
channel.execute('echo Hello')

Reading Output

size, data = channel.read()
while(size > 0):
    print(data)
    size, data = channel.read()

Hello

Exit Code

print("Exit status: %s" % (channel.get_exit_status()))

Exit status: 0

Public Key Authentication

session.userauth_publickey_fromfile(
    username, 'my_pkey.pub', 'my_pkey', '')

Where '' can be a passphrase.

Password Authentication

session.userauth_password(
    username, '<my password>')

SFTP Read

sftp = session.sftp_init()
with sftp.open(<remote file to read>, 0, 0) as remote_fh, \
        open(<file to write>, 'wb') as local_fh:
    for size, data in remote_fh:
        local_fh.write(data)

Complete Example

A simple usage example looks very similar to libssh2 usage examples.

See examples directory for more complete example scripts.

As mentioned, ssh2-python is intentially a thin wrapper over libssh2 and directly maps most of its API.

Clients using this library can be much simpler to use than interfacing with the libssh2 API directly.

from __future__ import print_function

import os
import socket

from ssh2.session import Session

host = 'localhost'
user = os.getlogin()

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((host, 22))

session = Session()
session.handshake(sock)
session.agent_auth(user)

channel = session.open_session()
channel.execute('echo me; exit 2')
size, data = channel.read()
while size > 0:
    print(data)
    size, data = channel.read()
channel.close()
print("Exit status: %s" % channel.get_exit_status())

Output:

me

Exit status: 2

SSH Functionality currently implemented

• SSH channel operations (exec,shell,subsystem) and methods

• SSH agent functionality

• Public key authentication and management

• SFTP operations

• SFTP file handles and attributes

• SSH port forwarding and tunnelling

• Non-blocking mode

• SCP send and receive

• Listener for port forwarding

• Subsystem support

And more, as per libssh2 functionality.

Native Code Extension Features

The library uses Cython based native code extensions as wrappers to libssh2.

Extension features:

• Thread safe - GIL is released as much as possible

• Very low overhead

• Super fast as a consequence of the excellent C library it uses and that it uses native code prodigiously

• Object oriented - memory freed automatically and safely as objects expire

• Use Python semantics where applicable, such as iterator support for reading from SFTP file handles

• Expose errors as Python exceptions where possible

• Provide access to libssh2 error code definitions

Comparison with other Python SSH libraries

Performance of above example, compared with Paramiko.

time python examples/example_echo.py
time python examples/paramiko_comparison.py

Output:

ssh2-python:

real       0m0.141s
user       0m0.037s
sys        0m0.008s

paramiko:

real       0m0.592s
user       0m0.351s
sys        0m0.021s