theClimber

What is gettext and why use it?

gettext is the GNU internationalization and localization (i18n) library. It is commonly used for writing multilingual programs. It has an implementation in a lot of different languages and it's also commonly used in PHP applications.

But what does you mean by internationalisation? Actually, when you write computer code you are also going to write into your code some sentences which will be prompted to the used who is running the application. Those sentences are always written in a language of your choice. But what if that person doesn't understand that language.

The first reaction to solve this problem would be to say : "Ok, but I'm gonna make another version of the code in an other language. I'll translate all those sentences so that my application could be used by other people". And we agree, this is indeed the first solution we get. But this is not optimal since you decide to modify your intial app, you'll have to modify all the translated app too and this is not an issue. It's totally broken to work like this because it imply an enormous quantity of duplicated code and a big amount of work !

That's the moment when gettext came and solved all your problems ! Indeed, the gettext solution proposes te replace all those strings with a call to a gettext function with your sentence as parameter. This function check the chosen language and if it knows a translation of the sentence in that language, it returns the translated sentence, otherwise it returns the initial sentence.

Purpose

To have a mail server Which is working with sessions organised in a postgresql database structure and not based on the unix user sessions

Version of the used software for this tutorial

- Ubuntu 8.10 Intrepid server edition - Courier-imap 4.3.1 - Postfix 2.5.5 - postgresql 8.3

I started from a new installation of my distribution so all the actions described here are from scratch.

This is a small python script which can be used to extract the local IP address of a host in function of his interface. You can modify this script to adapt it to your purposes.

#!/usr/bin/python
# Shell script scripts to read ip address
# -------------------------------------------------------------------------
# Copyright (c) 2008 Greg theClimber <http://www.theclimber.be/>
# This script is licensed under GNU GPL version 3.0
# -------------------------------------------------------------------------
from commands import *
import getopt
import sys

def usage():
	print "Usage : python getip.py [(-i | --interface) name]"

try:
	opts, args = getopt.getopt(sys.argv[1:], "hi:", ["help", "interface="])
except getopt.GetoptError, err:
	# print help information and exit:
	print str(err) # will print something like "option -a not recognized"
	usage()
	sys.exit(2)
intf = None
for o, a in opts:
	if o in ("-h", "--help"):
		usage()
		sys.exit()
	elif o in ("-i", "--interface"):
		intf = a
	else:
		assert False, "unhandled option"

os=getoutput('uname')
ifs=getoutput('ifconfig | grep "Ethernet" | grep -v "vnet" | cut --delimiter=L -f1').splitlines()
interfaces=[]

linux="ifconfig %s | grep 'inet '| grep -v '127.0.0.1' | cut -d: -f2 | awk '{ print $1}'"
freebsd="ifconfig %s | grep -E 'inet.[0-9]' | grep -v '127.0.0.1' | awk '{ print $2}'"
sunos="ifconfig -a %s | grep inet | grep -v '127.0.0.1' | awk '{ print $2}'"

if not intf:
	print "Please select the interface to use :"
	for n, i in enumerate(ifs):
		i = i.rstrip(' ')
		interfaces.append(i)
		print "%s) %s" % (n, i)
	print "default = 0"
	try:
		num = input()
		num = int(num)
		i = interfaces[num]
	except: num=0
else:
	i = intf

if i:
	if os == 'Linux':
		ip = getoutput(linux % i)
	elif os =='FreeBSD':
		ip = getoutput(freebsd % i)
	elif os == 'SunOS':
		ip = getoutput(sunos % i)
	else:
		ip = "Unknown"
#	print "%r:%r" % (i, ip)

print ip

Overview

djbdns is a DNS server which want to propose an alternative solution for BIND which is the warlord concerning DNS servers and which is widely used. The thing is that even if BIND is a very complete implementation of the DNS functionalities, it has a very heavy footprint which means that it’s not very flexible and usable on low-performance servers. On the other hand, DJBdns is optimized to have a very light footprint and very secure (instead of bind which is a lot less).

DJBdns developed by D.J. Bernstein, is oriented light and secure before its completeness. Moreover, the developer propose $1000 to the person who officially publish a security hole into his software. This is a good way to improve his software by motivating people to find bugs.

In this tutorial we will see how to install and use this lightweight DNS server. This tutorial was made on and works fine on Ubuntu 8.10 and 8.04. Because it’s not se easy to install, every step is detailed separately.

Your djbdns installation can be easy or hard. If you want it easy, it’s important to do it in the correct order:

1. Download source tarballs for daemontools, ucspi-tcp and djbdns
2. Install daemontools
3. Install ucspi-tcp
4. Install djbdns
5. Configure dnscache on an alias to the network card
6. Configure tinydns on the external IP
7. Link dnscache to tinydns

Daemontools and ucspi-tcp are systems that launch most DJB software, including djbdns. Daemontools is a system for launching daemons, very similar to the scripts in the /etc/rc.d tree. ucspi-tcp is a system for running background software, very similar to the inetd and xinetd systems on a normal Linux system. Daemontools and ucspi-tcp coexist with /etc/rc.d, inetd and xinetd perfectly.

Let’s begin by installing squid:

sudo apt-get install squid

To use squid, we just need to configure our web browser with the good proxy. By default squid listen on port 3128 and works without any modification in the configuration needed.

Moreover, we can add some optimizations to adapt the server to our needs. The configuration file is in /etc/squid/squid.conf.

The important parameters are the followings :

• http_port 3128 (it’s the default working port of a proxy server, you can change it here)
• cache_effective_user nobody nobody (user to assign a user or a groud to the proxy server)
• visible_hostname cache.knowledgeplaza.lan (it’s the name returned by the proxy when it’s reached from outside)
• cache_mem 20 MB (this is the allocated memory to the server).
• cache_dir /cache 3200 16 256 (here you can indicate the folder you want to use to save the cache)
• cache_access_log /var/log/squid/access.log (save the requests log)
• cache_log /var/log/squid/cache.log (save the cache log)
• cache_store_log none (save the events that happened on the server)

You can also specify the access control on the proxy : http_access allow all (to allow everyone to use this server)

To test the proxy, set the environment http_proxy to the good value :

export http_proxy=http://127.0.0.1:6681

After that, just try to download a big image on the internet :

wget http://image_url

Try it a second time, with the same request. Normally it will be a lot faster than the first time.

Finalize

To activate the proxy server on each startup of the server, add into the bash preferences /etc/bash.bashrc the next line :

export http_proxy=http://127.0.0.1:8081

More references :

• http://doc.ubuntu-fr.org/squid
• http://stargate.ac-nancy-metz.fr/li…
• http://doc.ubuntu-fr.org/serveur