Linux - Proxy Cache SQUID (ACLs)

If you need restrict the access to determined web sites for a subset of computers inside a LAN, then it could work for you . It work for me ;)
Edit the configuration of your SQUID (squid.conf)

# add these ACLs
acl netSubsetLAN src "/etc/squid/subsetLAN"
acl govar_all dstdomain -i .gov.ar
acl webDomain dstdomain "/etc/squid/webDomain"
acl webIPs dst "/etc/squid/webIPs"

# add these lines before the line http_access deny all
http_access allow netSubsetLAN
http_access allow netSubsetLAN webIPs
http_access allow netSubsetLAN webDomain
http_access allow netSubsetLAN govar_all



A very brief description:

The file "/etc/squid/subsetLAN" define an IP for each line. The IPs here are for the subset of IPs inside the LAN. For example,
192.168.1.20
192.168.1.21
192.168.1.22

The ACL govar_all defines a subset of destination domains where all domains with *.gov.ar will belong to this subset.

The file "/etc/squid/webDomain" define a domain for each line. For example,
www.google.com
maps.google.com


The file "/etc/squid/webIPs" define an IP for each line. The IPs here are for the destination IPs. You could use the command dig in a terminal. For example, open a terminal and type: dig www.google.com to find out the IPs of it domain. Then add them to this file.


http_access allow netSubsetLAN webDomain, it define an AND operation between netSubsetLAN and webDomain. It means, is allowed the http access for the IPs defined in netSubsetLAN only for those domains defined in webDomain.

References:

     Concepto de ACL en SQUID

     Squid Cache Wiki

     email list - ACL squid?

Linux - connected by 3G modem (Ubuntu Hardy)

To connect to Internet by mean a usb modem with 3G technology, you could use GNOME PPP or Vodafone Mobile Connect Card driver for Linux (Vodafone 3G devices Internet connection assistant).

sudo apt-get install gnome-ppp
or
sudo apt-get install vodafone-mobile-connect-card-driver-for-linux

I used GNOME PPP for the first time connection, to find out DNS's and auto-detect the modem device. This information is available in the log file.

Linux - Install man pages (Ubuntu Hardy)

In order to be able to read C/C++ man pages in a Terminal,
type these commnads:

$ sudo apt-get install manpages-posix-dev - for c headers
$ sudo apt-get install manpages-dev - for c functions

First, you could look the output of
$ sudo apt-cache search manpages

Reference:
http://ubuntuforums.org/showthread.php?t=10420

Linux - Install Mplayer and Multimedia Codecs

Install libdvdcss2 and w32 video codecs in Ubuntu 8.04 (Hardy Heron)

Support for WMV, RealMedia and other formats has been bundled into the w32codecs package. This package is not available from the Ubuntu repositories due to licensing and legal restrictions.

For Ubuntu 8.04 (Hardy Heron) Users run the following command

sudo wget http://www.medibuntu.org/sources.list.d/hardy.list -O /etc/apt/sources.list.d/medibuntu.list

Then, add the GPG Key using the following commands

sudo apt-get update

sudo apt-get install medibuntu-keyring

sudo apt-get update

For i386 Users install Codecs using the following command

sudo apt-get install w32codecs libdvdcss2

For amd64 Users install Codecs using the following command

sudo apt-get install w64codecs libdvdcss2

Using above download locations you can install most of the mutimedia codecs for ubuntu.

Mplayer Plugin for Firefox

If you want to install Mplayer with plug-in for Mozilla Firefox run the following command

sudo apt-get install mozilla-mplayer

Note: When I finished the installation above described, I must restart my computer in order to take the new packages. Then I could play videos with audio.

Install a different media player (optional)

The default media player (totem) is good, but I like vlc media player better, especially for watching a dvd.

In a terminal

sudo apt-get install vlc

References:

http://blog.csdn.net/emlinux/archive/2008/05/03/2370050.aspx

http://linuxowns.wordpress.com/2008/06/23/install-audio-and-video-codecs-in-ubuntu/

Python - keyGenerator class

Here is a very simple code to generate randomly a password with a predetermined size.
It would be better written with a switch case sentence instead of nested if-then-else sentences.

========================================================
import crypt
import string
from random import choice

class keyGenerator:
     def __init__(self, password_size):
     self.size = password_size
     self.flag_letters = True
     self.flag_digits = True
     self.letters_lower = True
     self.password_user = ''


     def generatePassword(self):
     # password with letters and digits
          if ( (self.flag_letters == True) and (self.flag_digits == True) ):
               self.password_user = ''.join ( [ choice(string.letters +
                              string.digits ) for i in range ( self.size ) ] )
          else:
               # password with digits, but without letters
               if ( (self.flag_letter == False) and (self.flag_digits == True)):
                    self.password_user = ''.join ( [ choice( string.digits )
                                             for i in range ( self.size ) ] )
               else:
                    # password with letters, but without digits
                    if ( (self.flag_letter == True) and
                         (self.flag_digits == False)):
                         self.password_user = ''.join ( [ choice(string.letters )
                                             for i in range ( self.size ) ] )
                    else:
                         print "Error: Letters and digits cannot be false
                                together! \n"

          # password with letters lower or upper
          if (self.letters_lower == True):
               self.password_user = string.lower( self.password_user )
          else:
               self.password_user = string.upper( self.password_user )


     def get_passwordUser(self):
          return self.password_user

References:
     Programming in Python - Generating a random string

Python - LDAP user management

This post will be ready in a few days.... be patient:
in advance, here is available the program code

========================================================

Installing Python-LDAP requires only one commnad:

$ sudo apt-get install python-ldap


#!/usr/bin/python

import ldap
import ldif
import MySQLdb
import sys
from myldapClass import *
from keyGenerator import *

class myLDIF:
     def __init__(self, database, user_db, passw_db, db):
          self.database = database
          self.user_db = user_db
          self.passw_db = passw_db
          self.db = db

     def connect(self):
          try:
               print 'connecting to database...'
               self.conn = MySQLdb.connect( host=self.database, user=self.user_db,passwd=self.passw_db, db=self.db  )
               self.conn.set_character_set('utf8')
          except MySQLdb.Error, e:
               print "Error %d: %s" % (e.args[0], e.args[1])
               sys.exit (1)
               print 'succesfully connected...'

          def get_row(self, ldap_conn, base_dn_toAdd):
               try:
                    cursor = self.conn.cursor()
                    cursor.execute ("SELECT * FROM princi ORDER BY legajo")

                    result_set = cursor.fetchall()
                    for row in result_set:
                         #print "%s, %s, %s" % (row[0], row[1], row[2])
                         if ( row[1].find(',') != -1):
                              #split by the first comma character
                              apellido, nombre = row[1].split(',',1)
                         else:
                              #split by the first whitespace
                              apellido1, nombre1 = row[1].split(' ',1)


                         dni = row[5].__str__()

                         dn = 'uid=' + dni + ',' + base_dn_toAdd
                         search_filter = '(objectclass=*)'
                         attrs = ['cn','sn', 'employeeNumber']

                         ldap_conn.search(dn, ldap.SCOPE_SUBTREE, search_filter, attrs)
                         if (ldap_conn.result_count > 0):
                              print 'This user already exist in the Ldap Server'
                         else:
                              # add this user to Ldap Server
                              kg = keyGenerator(9)
                              kg.generatePassword()

                              password_user = kg.password_user
                              legajo = row[0].__str__()

                              entry={'objectClass':['top','person','organizationalPerson','inetOrgPerson'],'cn':[nombre[1:]+' '+ apellido],'sn':[apellido], 'employeeNumber':[legajo],'mail':['cambiar@noexiste.com'],'uid':[dni],'userPassword':[password_user]}
                              ldif_writer=ldif.LDIFWriter(sys.stdout)
                              ldif_writer.unparse(dn,entry)

                              ldap_conn.addEntry(dn, entry)


                    cursor.close()

     except MySQLdb.Error, e:
          print "Error %d: %s" % (e.args[0], e.args[1])
          sys.exit (1)

def close(self):
     self.conn.close()

======================

change this references!

References:
   http://www.grotan.com/ldap/python-ldap-samples.html
   http://python-ldap.sourceforge.net/doc/html/index.html
   http://www.linuxjournal.com/article/6988
   http://python-ldap.sourceforge.net/apps.shtml
   http://www.iaeste.or.at/doc/python-ldap-doc/html/node3.html
   http://www.packtpub.com/article/installing-and-configuring-the-python-ldap-library-and-binding-to-an-ldap-directory

Python using Ldap Module

Here's an Ldap class using Ldap module.
Installing Python-LDAP requires only one commnad:

$ sudo apt-get install python-ldap


#!/usr/bin/python

import ldap
import ldap.modlist as modlist
import sys

class myLDAPClass:
     def __init__(self):
          self.result_count = 0

     def simpleAuthentication(self, server, admin_dn, pw):
          try:
               # Open a connection
               self.l = ldap.initialize(server)

               # you shoud set this to ldap.VERSION2 if you're using a Version2 directory
               self.l.protocol_version = ldap.VERSION3

               # Pass in a valid username and password to get
               # privileged directory access.
               # If you leave them as empty strings or pass an invalid value
               # you will still bind to the server but with limited privileges.
               self.admin_dn = admin_dn
               self.pw = pw

               # Any errors will throw an ldap.LDAPError exception
               # or related exception so you can ignore the result
               if (self.l.simple_bind(self.admin_dn, self.pw)):
                    print "Connected, simple bind, to Ldap Server ..."
               else:
                    print "Could not connect to Ldap Server."
                    sys.exit()

          except ldap.LDAPError, e:
               print e

     def close(self):
          self.l.unbind_s()
          print "Disconnected, unbind, to Ldap Server ..."

     def addEntry(self, dn, entry):
          # convert our dictionary to nice syntax for the add-function using modlist-module
          ldif = modlist.addModlist(entry)

          # Do the actual synchronous add-operation to the ldapserver
          self.l.add_s(dn, ldif)

     def delEntry(self, dn):
          try:
               # you can safely ignore the results returned as an exception
               # will be raised if the delete operation doesn't work
               self.l.delete_s(dn)
          except ldap.LDAPError, e:
               print e

     def search(self, base_dn, scope, search_filter, retrieve_attributes):
          self.result_count = 0
          try:
               ldap_result_id = self.l.search(base_dn, scope, search_filter, retrieve_attributes)
               self.result_set = []
               while 1:
                    result_type, result_data = self.l.result(ldap_result_id, 0)
                    if (result_data == []):
                         break
                    else:
                         if result_type == ldap.RES_SEARCH_ENTRY:
                              self.result_set.append(result_data)
                              # counting total of data
                              self.result_count = self.result_count + 1

                    #print self.result_set
          except ldap.LDAPError, e:
               print "No hay registro en LDAP server : ",e
               self.result_count = 0

if __name__ == "__main__":
     # here's an example of how to use this class.
     myldap = myLDAPClass()
     myldap.simpleAuthentication('ldap://localhost','o=organization,dc=gov.ar','secret')
     myldap.search('cn=name surname,ou=people,o=organization,dc=org', ldap.SCOPE_SUBTREE, '(objectclass=*)', ['employeeNumber'])

     # it use a dictionary to add an entry in Ldap Server
     entry={'objectClass':['top','person','organizationalPerson','inetOrgPerson'],'cn':['name surname'],'sn':['surname'], 'employeeNumber':['9999'],'mail':['test@change.com'],'uid':['1111'],'userPassword':['123456']}
dn='cn=name surname,ou=people,o=organization,dc=org'

     myldap.addEntry(dn, entry)
     myldap.close()

References:
   http://www.grotan.com/ldap/python-ldap-samples.html
   http://python-ldap.sourceforge.net/doc/html/index.html
   http://www.linuxjournal.com/article/6988
   http://python-ldap.sourceforge.net/apps.shtml
   http://www.iaeste.or.at/doc/python-ldap-doc/html/node3.html
   http://www.packtpub.com/article/installing-and-configuring-the-python-ldap-library-and-binding-to-an-ldap-directory

Programming in Python - Generating a random string

A quick, simple password generator.

Obviously there's no real crypto here. It is usefull, for example, regenerating and emailing a user password.

1. import string
2. from random import choice
3. 
   
4. size=9
5. pwd = ''.join ( [ choice (string.letters + string.digits ) for i in range ( size ) ]
6. 
   
7. # Putting in practice the string module
   
8. print pwd.lower

There's an application written in Python to generate random passwords for use wherever good (or bad) passwords are required. It is PyKey.