HOWTO : IPython for Python programming on Ubuntu

The current IPython is for Python 2.5 at this writing.
Install IPython as your Python programming environment.
sudo apt-get update
sudo apt-get install python-setuptools
sudo easy_install IPython
Once IPython is installed, you can run it as the following :
ipython
Type quit() to quit.

HOWTO : Fail2ban on Ubuntu 9.04 Server

Fail2ban cannot work properly with Ubuntu 9.04 Server as Ubuntu installed with Python 2.6. It is very easy to overcome this problem.
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install python2.5
sudo nano /usr/bin/fail2ban-server
Change the first line from
#!/usr/bin/python
to
#!/usr/bin/python2.5
Set the /etc/fail2ban/jail.conf as usual.
sudo /etc/init.d/fail2ban restart