Python Twisted Examples

This page maintained by Jacob Mathai.

http://www.jacobmathai.org

• Twisted is an open source network framework written entirely in Python. It allows you to create a SMTP, HTTP, proxy and ssh servers in Python with minimal effort. Twisted is Asynchronous and event driven and allows applications to respond to different network connection without the use of traditional threading models.

• Be Sure to Download the Twisted Sumo 2.1 (main Twisted package),PyOpenSSL, and PyCrypto (cryptographic libraries and primitives for ssh connections) before running these Python Twisted examples.

• Install the ZopeInterface that is bundled with the Twisted Sumo download before installing Twisted. (cd ZopeInterface* && python setup.py install)

• Install Twisted. (python setup.py install)

• Install PyOpenSSL. (make sure you have base openssl installed on the system) If during the PyOpenSSL install, you see any errors about Kerberos header files, try this:

If your OpenSSL ore kerberos header files are not in /usr/include, you may need to supply the -I flag to let the setup script know where to look. The same goes for the libraries of course, use the -L flag. Note that build won't accept these flags, so you have t o run first build_ext and then build! Example:

• python setup.py build_ext -I/usr/kerberos/include (or wherever your header files are) python setup.py build python setup.py install

• Install Pycrypto. (python setup.py install)

• Verify that all the package are installed correctly by importing pyOpenSSL-0.7, twisted, Crypto from a python shell and we are ready to go.

Simple HTTP Proxy Server (proxy.py)

from twisted.web import proxy, http
from twisted.internet import reactor
from twisted.python import log
import sys
log.startLogging(sys.stdout)
 
class ProxyFactory(http.HTTPFactory):
    def __init__(self):
        http.HTTPFactory.__init__(self)
        self.protocol = proxy.Proxy
 
reactor.listenTCP(8080, ProxyFactory())
reactor.run()

• Execute the above Twisted python example script (python proxy.py) You may see a Deprecation Warning that you can ignore for this example.

[jacob@tux]$ python proxy.py
/usr/lib/python2.3/site-packages/twisted/web/proxy.py:22: DeprecationWarning: twisted.protocols.http has moved to twisted.web.http. See http://twistedmatrix.com/projects/web.
  from twisted.protocols import http
2005/12/06 21:47 EST [-] Log opened.
2005/12/06 21:47 EST [-] __main__.ProxyFactory starting on 8080
2005/12/06 21:47 EST [-] Starting factory <__main__.ProxyFactory instance at 0xb73577ac>

• Connect your internet browser to the proxy server you just created (localhost:8080) and you have written a simple proxy server using Python and Twisted.