Python
  Home arrow Python arrow Page 4 - SSH with Twisted
Dev Shed Forums 
Administration  
Apache  
BrainDump  
DHTML  
Flash  
Java  
JavaScript  
Multimedia  
MySQL  
Oracle  
Perl  
PHP  
Practices  
Python  
Reviews  
Security  
Style-Sheets  
Web Services  
XML  
Zend  
Zope  
Forums Sitemap 
IBM® developerWorks 
Dedicated Servers 
E-Commerce Hosting 
Linux Web Hosting 
Managed Hosting 
Small Business Hosting 
Download TestComplete 
VPS Hosting 
Weekly Newsletter

 
Developer Updates  
Free Website Content 
IBM Rational Software Development Conference
 RSS  Articles
 RSS  Forums
 RSS  All Feeds
Write For Us Get Paid 
Request Media Kit
Contact Us 
Site Map 
Privacy Policy 
Support 
 USERNAME
 
 PASSWORD
 
 
  >>> SIGN UP!  
  Lost Password? 
PYTHON

SSH with Twisted
By: O'Reilly Media
  • Search For More Articles!
  • Disclaimer
  • Author Terms
  • Rating: 5 stars5 stars5 stars5 stars5 stars / 2
    2008-03-06

    Table of Contents:
  • SSH with Twisted
  • Setting Up a Custom SSH Server continued
  • Using Public Keys for Authentication
  • Providing an Administrative Python Shell
  • Running Commands on a Remote Server

  • Rate this Article: Poor Best 
      ADD THIS ARTICLE TO:
      Del.ici.ous Digg
      Blink Simpy
      Google Spurl
      Y! MyWeb Furl
    Email Me Similar Content When Posted
    Add Developer Shed Article Feed To Your Site
    Email Article To Friend
    Print Version Of Article
    PDF Version Of Article
     
     
     
    ADVERTISEMENT

    PCmover - $15 Off with Coupon Code CJPH7Q

    SSH with Twisted - Providing an Administrative Python Shell
    (Page 4 of 5 )

    Example 10-1 demonstrated how to provide an interactive shell through SSH. That example implemented its own language with a small set of commands. But there’s another kind of shell that you can run over SSH: the same interactive Python prompt you know and love from the command line.

    How Do I Do That?

    The twisted.conch.manhole and twisted.conch.manhole_ssh modules have classes designed to provide a remote interactive Python shell inside your running server. Create a manhole_ssh.TerminalRealm object and set its chainedProtocolFactory.protocolFactoryattribute to a function that will returnmanhole.Manholeobjects. Example 10-3 demonstrates a web server that can be modified on the fly using SSH andtwisted.conch.manhole.

    Example 10-3. manholeserver.py

    from twisted.internet import reactor
    from twisted.web import server, resource from twisted.cred import portal, checkers from twisted.conch import manhole, manhole_ssh

    class LinksPage(resource.Resource):
        isLeaf = 1

        def __init__(self, links):
            resource.Resource.__init__(self)
            self.links = links

        def render(self, request):
           
    return "<ul>" + "".join([
               
    "<li><a href='%s'>%s</a></li>" % (link, title)
               
    for title, link in self.links.items()]) + "</ul>"

    links = {'Twisted': 'http://twistedmatrix.com/',
            
    'Python': 'http://python.org'}
    site = server.Site(LinksPage(links)) reactor.listenTCP(8000, site)

        def getManholeFactory(namespace, **passwords):
            realm = manhole_ssh.TerminalRealm()
            def getManhole(_): return manhole.Manhole(namespace) 
      realm.chainedProtocolFactory.protocolFactory = getManhole
            p = portal.Portal(realm)
            p.registerChecker(
               
    checkers.InMemoryUsernamePassword DatabaseDontUse(**passwords))
            f = manhole_ssh.ConchFactory(p)
            return f

    reactor.listenTCP(2222, getManholeFactory(globals(), admin='aaa'))
    reactor.run()

    manholeserver.py will start up a web server on port 8000 and an SSH server on port 2222. Figure 10-1 shows what the home page looks like when the server starts.


    Figure 10-1.  The default manholeserver.py web page

    Now log in using SSH. You’ll get a Python prompt, with full access to all the objects in the server. Try modifying thelinksdictionary:

      $ ssh admin@localhost -p 2222
      admin@localhost's password:
    aaa

      >>> dir()
      ['LinksPage', '__builtins__', '__doc__', '__file__', '__name_ _', 'checkers',
      'getManholeFactory', 'links', 'manhole', 'manhole_ssh', 'portal', 'reactor',
      'resource', 'server', 'site']
      >>> links
     
    {'Python': 'http://python.org', 'Twisted': 'http://twistedmatrix.com/'}
      >>> links["Abe Fettig"] = http://fettig.net
      >>> links["O'Reilly"] = http://oreilly.com
      >>> links
      {'Python': 'http://python.org', "O'Reilly": 'http://oreilly.com', 'Twisted': 'http:// twistedmatrix.com/', 'Abe Fettig': 'http://fettig.net'}
      >>>

    Then refresh the home page of the web server. Figure 10-2 shows how your changes will be reflected on the web site.


    Figure 10-2.  The modified manholeserver.py web page

    How Does That Work?

    Example 10-3 defines a function called getManholeFactory that makes running a manhole SSH server trivially easy. getManholeFactorytakes an argument callednamespace, which is a dictionary defining which Python objects to make available, and then a number of keyword arguments representing usernames and passwords. It constructs amanhole_ssh.TerminalRealmand sets itschainedProtocolFactory.protocolFactoryattribute to an anonymous function that returnsmanhole.Manholeobjects for the requested namespace. It then sets up a portal using the realm and a dictionary of usernames and passwords, attaches the portal to a
    manhole_ssh.ConchFactory, and returns the factory.

    Like its name implies,manholeprovides a portal to something that is off-limits to the she is allowed in, she can do anything she wants. You can pass a dictionary of Python objects asnamespaceonly for the sake of convenience (to limit the set of objects the user has to look through), not for security. Only administrative users should have permission to use themanholeserver.

    Example 10-3 creates a manhole factory using the built-inglobals()function, which returns a dictionary of all the objects in the current global namespace. When you log in through SSH, you can see all the global objects in manholeserver.py, including thelinksdictionary. Because this dictionary is also being used to generate the home page of the web site, any changes you make through SSH are instantly reflected on the Web.

    Themanhole_ssh.ConchFactoryclass includes its own default public/private key pair. For your own projects you shouldn’t rely on these built-in keys. Instead, generate your own and set thepublicKeys andprivateKeysattributes of theConchFactory. See Example 10-1, earlier in this chapter, for an example of how to do this.

    More Python Articles
    More By O'Reilly Media


       · This article is an excerpt from the book "Twisted Network Programming Essentials,"...
     

    Buy this book now. This article is excerpted from chapter 10 of the book Twisted Network Programming Essentials, written by Abe Fettig (O'Reilly, 2007; ISBN: 0596100329). Check it out today at your favorite bookstore. Buy this book now.

       

    PYTHON ARTICLES

    - SSH with Twisted
    - Mobile Programming in Python using PyS60: UI...
    - Python: Count on It
    - Python Strings: Spinning Yarns
    - Python: More Fun with Strings
    - Python: Stringing You Along
    - Python Operators
    - Bluetooth Programming in Python: Network Pro...
    - Python Sets
    - Python Conditionals, Lists, Dictionaries, an...
    - Python: Input and Variables
    - Introduction to Python Programming
    - Mobile Programming in Python using PyS60: Ge...
    - Bluetooth Programming using Python
    - Finishing the PyMailGUI Client: User Help To...




    © 2003-2008 by Developer Shed. All rights reserved. DS Cluster 4 hosted by Hostway