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https://github.com/dsoprea/PySecure

A complete Python SSH/SFTP library based on libssh.
https://github.com/dsoprea/PySecure

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A complete Python SSH/SFTP library based on libssh.

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README 

        
Introduction

------------



This is a library that provides SSH and SFTP functionality from within Python,

using "libssh". Although libssh2 was considered, it appears that its SFTP 

functionality is slower (1).



This solution exists as an alternative to Paramiko. I love Paramiko, but as 

"libssh" is very complete and actively-maintained, it has a greater breadth of 

functionality, such as support for elliptic-curve encryption (recently added). 

It is also written in C.



This project is in active development. It -is- Python3 compatible.



(1) http://daniel.haxx.se/blog/2010/12/05/re-evaluating-the-criticism/



Status

------



| Done | Description |

|:----:| ----------- |

| X | SFTP functionality |

| X | Local port forwarding |

| X | Reverse port forwarding |

| X | Remote command (single commands) |

| X | Remote execution (shell session) |

|   | Threading support |

|   | Support X11 forwarding (waiting on libssh) |

| X | Added SFTP "mirror" functionality |



Remote execution is currently broken in libssh 0.6.0, but our library is no 

longer compatible with 0.5.5 (key-related changes involved new/changed 

functions in libssh).



Dependencies

------------



- libssh 0.6.0rc1



Installing

----------



Just expand, and make sure PYTHONPATH includes the directory.



NOTE: Though this project is on PyPI, it's -highly- recommended to use

      "easy_install" to get it, rather than "pip". The latter has the tendency

      to not get the latest version.



Logging

-------



To allow for standard logging to go out to the console, import 

"pysecure.log_config". 



To enable "debug" logging, set the environment variable

"DEBUG" to "1". 



To enable debug verbosity from the "libssh" library, pass the

"verbosity" argument into the connect_* functions with a value of True.



Common Setup Code for Examples

------------------------------



To make the examples more concise, some code has been removed, so as to not be 

repeated in every case.



A complete, working example using some included convenience functions would 

look like the following:



```python

from pysecure.easy import connect_ssh, connect_sftp, get_key_auth_cb



user = 'dustin'

host = 'localhost'

key_filepath = '/home/dustin/.ssh/id_dsa'



auth_cb = get_key_auth_cb(key_filepath)



# For simple SSH functionality.



with connect_ssh(user, host, auth_cb) as ssh:

    # Main logic, here.

    pass



# Or, for SFTP-enabled SSH functionality.



with connect_sftp(user, host, auth_cb) as (ssh, sftp):

    # Main logic, here.

    pass



```



SFTP Examples

-------------



File resources are file-like objects that are similar to standard file objects. 

Calls will have traditional methods, as identified here: 

    

    http://docs.python.org/2/library/stdtypes.html#file-objects



List a directory:



```python

from pysecure.adapters.sftpa import SftpFile



print("Name                         Size Perms    Owner\tGroup\n")

for attributes in sftp.listdir('.'):

    print("%-40s %10d %.8o %s(%d)\t%s(%d)" % 

          (attributes.name[0:40], attributes.size, 

           attributes.permissions, attributes.owner, 

           attributes.uid, attributes.group,

           attributes.gid))

```



Recurse a directory:



```python

def dir_cb(path, entry):

    full_path = ('%s/%s' % (path, entry.name))

    print("DIR: %s" % (full_path))



def listing_cb(path, list_):

    print("[%s]: (%d) files" % (path, len(list_)))



sftp.recurse('Pictures', dir_cb, listing_cb)

```



Read through text-file, one line at a time:



```python

with SftpFile(sftp, 'text_file.txt') as sf:

    i = 0

    for data in sf:

        stdout.write("> " + data)



        if i >= 30:

            break



        i += 1

```



To read a complete file (binary friendly). It could also be read one chunk at a 

time:



```python

with SftpFile(sftp, 'binary_file.dat') as sf:

    buffer_ = sf.read()



    print("Read (%d) bytes." % (len(buffer_)))

```



Mirroring:



```python

from pysecure.sftp_mirror import SftpMirror



mirror = SftpMirror(sftp)



# Mirror from server to local.

mirror.mirror(mirror.mirror_to_local_no_recursion, 

              "Pictures", 

              "/tmp/Pictures")



# Mirror from local to server.

mirror.mirror(mirror.mirror_to_remote_no_recursion, 

              "/home/dustin/Pictures", 

              "/tmp/RemotePictures")

```



Mirroring will ignore special (device) files. It also won't specially 

handle hard-links.



Port-Forwarding Examples

------------------------



Local Forwarding:



```python

from pysecure.adapters.channela import SshChannel



host_source = 'localhost'

port_local = 1111

host_remote = 'localhost'

port_remote = 80



data = "GET / HTTP/1.1\nHost: localhost\n\n"



with SshChannel(ssh) as sc:

    # The following command activates forwarding, but does not bind any

    # ports. Although a "port_local" parameter is expected, this is 

    # allegedly for little more than logging. Binding is left as a concern

    # for the implementing developer.

    sc.open_forward(host_remote, port_remote, host_source, port_local)



    sc.write(data)



    received = sc.read(1024)

    print("Received:\n\n%s" % (received))

```



Reverse Forwarding:



```python

# This functionality starts with an SshSession. Therefore, an import of

# SshChannel isn't necessary.



server_address = None

server_port = 8080

accept_timeout_ms = 60000



port = ssh.forward_listen(server_address, server_port)

with ssh.forward_accept(accept_timeout_ms) as sc:

    while 1:

        data = sc.read(2048)

        if data == '':

            continue



        # Do something with the data.

        response = "Received."



        sc.write(response)

```



Remote Execution

----------------



Remote Command (efficient for single command):



    This functionality can be used to execute one command at a time:



    ```python

    for line from ssh.execute('lsb_release -a'):

        print(line)



    data = ssh.execute('whoami')

    print(data)

    ```



    Output:



    ```

    Distributor ID:	Ubuntu

    Description:	Ubuntu 13.04

    Release:	13.04

    Codename:	raring



    dustin

    ```



Remote Shell (efficient for many commands):



    Example:



    ```python

    rsp = RemoteShellProcessor(ssh)

    

    def shell_context_cb(sc, welcome):

        output = rsp.do_command('cat /proc/uptime')

        print(output)



        output = rsp.do_command('whoami')

        print(output)

    

    rsp.shell(shell_context_cb)

    ```



    Output:



    ```

    $ PYTHONPATH=. test/example.py 

    631852.37 651773.95

    dustin

    ```



EasySsh

-------



We always recommend the use of the connect_ssh and connect_sftp calls mentioned 

above, as they are meant to be used with a context-manager ("with") block, and 

will automatically be cleaned-up properly. However, this strategy makes it 

impossible to keep a connection open while passing control back to the caller 

of the function, and therefoe requires that a new, subsequent connection is 

opened for the next operation.



Whereas the above strategy relies on the use of a callback when the SSH or SFTP

session(s) are ready, we also provide the EasySsh class to make it easy to open

a connection and close that connection at two separate times.



For example:



```python

from pysecure.easy import EasySsh, get_key_auth_cb



auth_cb = get_key_auth_cb(key_filepath)

easy = EasySsh(user, host, auth_cb)



easy.open_ssh()

easy.open_sftp()



# easy.ssh and, if opened, easy.sftp are now ready.



# Do your logic, here. For example, list directory entries.

entries = easy.sftp.listdir('.')



easy.close_sftp()   # We do this just to be explicit. This will 

                    # automatically be done at SSH close.

easy.close_ssh()

```