The majority of the web servers, that are based on Apache, have the mod_rewrite enabled so you don’t have to get dirty to install it on the hosting server.But anyone of those that are developing web application based on Apache server,  using PHP have a local installed server therefore mode_rewrite is also  necessary in testing process.

Installing mod_rewrite :

1. On Linux: edit the Apache configuration file (  httpd.conf ) and uncomment   LoadModule rewrite_module modules/mod_rewrite.so (remove the pound ‘#’ sign from in front of the line) . Also be sure that the lines containing ClearModuleList and AddModule mod_rewrite.c are uncommented . Now you can create the famous .htacess file on the root of you website and start adding your code.
2. On Windows: well as we are expecting, things are a bit more complicated because on Windows you cannot create a file that doesn’t have a name (.htacess is a file that only have an extension). For first just uncomment the same lines as in the Linux example. Now you have to tell Apache to use you’re custom file instead of  .htacess file, so search in the configuration file (httpd.conf)  for the following lines:

# AccessFileName: The name of the file to look for in each directory # for additional configuration directives. See also the AllowOverride
# directive.
#
AccessFileName .htaccess (change the .htaccess to [name].htaccess where name can be whatever what you wish )

You can escape this step and create the .htacess file even on windows, actually the restriction of creating a file without name is an restriction of Windows Explorer is not an restriction of the operating system . Open the command (cmd), go to the root folder of the website and type copy con .htacess and press Ctrl+Z. well… that’s all folks.

Maybe you are asking yourself  about mod_rewrite and where to use it, well the short and  simple answer is :  for simplifying the URL of a website, simpler/shorter URL are easier to write easier to remember. For example instead of having an URL  like this www.example.com?id_product=23123&color=23 you can have something like www.example.com/iphone-white. Mod_rewrite basicly make   use of regular expression to rewrite an specified URL.

When to use it: mod_rewrite can be used in many circumstances where you may want to rewrite the an URL, also you can create dynamically virtual hosting entry;  practically mode_rewrite is an “Swiss Army Knife”.

When not to use it: well as I have mentioned  before mode_rewrite make use of regular expression, and evaluating regular expression takes time, use memory and the global performance of the server is decreasing.

I will provide you some basic example of using mode_rewrite. .htaccess file should begin with:

Options +FollowSymLinks
RewriteEngine On
RewriteBase /

1. Redirecting
   Redirect /index.php   http://www.example.com/    -this example redirect the current site to www.example.com
   RedirectMatch (.*)\.gif http://images.example.com$1.png      -In this example, we’ve taken all of our GIF files, converted them to PNG files, and
   moved them to another server
2. Require www

   Options +FollowSymLinks
   RewriteEngine On
   RewriteBase /
   RewriteCond %{HTTP_HOST} !^www\.example\.com$ [NC]
   RewriteRule ^(.*)$ http://www.example.com/$1 [R=301,L]

3. Denying access to a folder except of fopen file from php

   RewriteEngine On
   RewriteBase /
   RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /([^/]+)/.*\ HTTP [NC]
   RewriteRule .* - [F,L]

4. Limit access during some hours

   Options +FollowSymLinks
   RewriteEngine On
   RewriteBase /
   # If the hour is 7
   RewriteCond %{TIME_HOUR} ^7$
   RewriteRule ^.*$ - [F,L]

These samples are here just to open your appetite for mode_rewrite. Practically this tool can be used in any other ways,yes… the limit is your imagination.

Well seriously, there are some meta methods to protect you’re HTML source from being seen by a common user not from an expert user.I will enumerate some methods starting with the simplest.

• The first method, maybe the most stupid one but used by many people (stupid ideas work for stupid people ) is putting a lot of empty line in front of HTML source. If the user looks at the source will see just empty white page. But if he scroll down on bottom of the page he will see the source.
• The  second method is to disable right click on page. To do that just take a look at next code://Disable right click script III- By Renigade (renigade@mediaone.net)
  //For full source code, visit http://www.dynamicdrive.com

  var message=”";
  ///////////////////////////////////
  function clickIE() {if (document.all) {(message);return false;}}
  function clickNS(e)
  {
  if(document.layers||(document.getElementById&&!document.all))
  {
  if (e.which==2||e.which==3)
  {(message);return false;}
  }
  }

  if (document.layers)
  {
  document.captureEvents(Event.MOUSEDOWN);document.onmousedown=clickNS;
  }
  else
  {
  document.onmouseup=clickNS;document.oncontextmenu=clickIE;
  }

  document.oncontextmenu=new Function(”return false”)
  // –>

  Now that the user can do right click->show page source,  you have achieved a good protection method,  if you user is a old granny  that doesn’t know to use  (Ctrl+U)  shortcut or Edit->View page soure.

• The third method is to use javascript to hide the HTML content. A short example is presented next:
  Let’s suppose that the page has the following code:<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>
  <html xmlns=”http://www.w3.org/1999/xhtml”>
  <head>
  <meta http-equiv=”Content-Type” content=”text/html; charset=utf-8″ />
  <title>Sample HTML-hide sorece code</title>
  </head>

  <body>
  Blah blah blah
  </body>
  </html>

  Now what we have to do next is to “encrypt” this content, go to http://www.swingnote.com/tools/texttohex.php or a similar page and convert the text source code to an hexa representation. You will obtain something similar to this:
  %3c%21%44%4f%43%54%59%50%45%20%68%74%6d%6c%20%50%55%42%4c%49%43%20%5c%22%2d%2f%2f%57%33%43%2f%2f%44%54%44%20%58%48%54%4d%4c%20%31%2e%30%20%54%72%61%6e%73%69%74%69%6f%6e%61%6c%2f%2f%45%4e%5c%22%20%5c%22%68%74%74%70%3a%2f%2f%77%77%77%2e%77%33%2e%6f%72%67%2f%54%52%2f%78%68%74%6d%6c%31%2f%44%54%44%2f%78%68%74%6d%6c%31%2d%74%72%61%6e%73%69%74%69%6f%6e%61%6c%2e%64%74%64%5c%22%3e%20%3c%68%74%6d%6c%20%78%6d%6c%6e%73%3d%5c%22%68%74%74%70%3a%2f%2f%77%77%77%2e%77%33%2e%6f%72%67%2f%31%39%39%39%2f%78%68%74%6d%6c%5c%22%3e%20%3c%68%65%61%64%3e%20%3c%6d%65%74%61%20%68%74%74%70%2d%65%71%75%69%76%3d%5c%22%43%6f%6e%74%65%6e%74%2d%54%79%70%65%5c%22%20%63%6f%6e%74%65%6e%74%3d%5c%22%74%65%78%74%2f%68%74%6d%6c%3b%20%63%68%61%72%73%65%74%3d%75%74%66%2d%38%5c%22%20%2f%3e%20%3c%74%69%74%6c%65%3e%53%61%6d%70%6c%65%20%48%54%4d%4c%2d%68%69%64%65%20%73%6f%72%65%63%65%20%63%6f%64%65%3c%2f%74%69%74%6c%65%3e%20%3c%2f%68%65%61%64%3e%20%20%3c%62%6f%64%79%3e%20%09%42%6c%61%68%20%62%6c%61%68%20%62%6c%61%68%20%3c%2f%62%6f%64%79%3e%20%3c%2f%68%74%6d%6c%3e

  The page is the same but now has a different representation that is strange to a common user but remember that this is a meta protection method an advanced user can and will do the reverse method to obtain you’re source.
  The next step is to create the “protected” page, create a new HTML document and add the next code:

  <script>
  document.write(unescape(”%3c%21%44%4f%43%54%59%50%45%20%68%74%6d%6c%20%50%55%42%4c%49%43%20%5c%22%2d%2f%2f%57%33%43%2f%2f%44%54%44%20%58%48%54%4d%4c%20%31%2e%30%20%54%72%61%6e%73%69%74%69%6f%6e%61%6c%2f%2f%45%4e%5c%22%20%5c%22%68%74%74%70%3a%2f%2f%77%77%77%2e%77%33%2e%6f%72%67%2f%54%52%2f%78%68%74%6d%6c%31%2f%44%54%44%2f%78%68%74%6d%6c%31%2d%74%72%61%6e%73%69%74%69%6f%6e%61%6c%2e%64%74%64%5c%22%3e%20%3c%68%74%6d%6c%20%78%6d%6c%6e%73%3d%5c%22%68%74%74%70%3a%2f%2f%77%77%77%2e%77%33%2e%6f%72%67%2f%31%39%39%39%2f%78%68%74%6d%6c%5c%22%3e%20%3c%68%65%61%64%3e%20%3c%6d%65%74%61%20%68%74%74%70%2d%65%71%75%69%76%3d%5c%22%43%6f%6e%74%65%6e%74%2d%54%79%70%65%5c%22%20%63%6f%6e%74%65%6e%74%3d%5c%22%74%65%78%74%2f%68%74%6d%6c%3b%20%63%68%61%72%73%65%74%3d%75%74%66%2d%38%5c%22%20%2f%3e%20%3c%74%69%74%6c%65%3e%53%61%6d%70%6c%65%20%48%54%4d%4c%2d%68%69%64%65%20%73%6f%72%65%63%65%20%63%6f%64%65%3c%2f%74%69%74%6c%65%3e%20%3c%2f%68%65%61%64%3e%20%20%3c%62%6f%64%79%3e%20%09%42%6c%61%68%20%62%6c%61%68%20%62%6c%61%68%20%3c%2f%62%6f%64%79%3e%20%3c%2f%68%74%6d%6c%3e”));
  </script>
  As you can see all we are doing is to use javascript to write the content (document.write method).
  !!! Important : if user has the javascript disabled he will not see anything because the code will not execute, therefore will  be nothing displayed. Also remember that most of searchengine as Google or Yahoo crawl  the web in text mode,  remember that javascript is luxury not a necessity.

• Now is time to get serious and speak about some more advanced, a little bit harder to break (not impossible to break), technique   to keep you HTML source protected.The base idea is to encrypt the content of the HTML page, this time really encryption . Let imagine  a function for encryption this time a simple one that is using xor logic function to achieve encryption. The code to do that is showed next:
  //Encryptionfunction encrypt(text,key){

  var rez=new Array(text.length);
  for(i=0;i<text.length;i++){
  rez[i]=text.charCodeAt(i) ^key.charCodeAt(i%key.length);
  }
  return rez;
  }

  //Decryption

  function decrypt(text,key){
  var rez=”";
  for(i=0;i<text.length;i++){
  rez+=String.fromCharCode(text[i] ^key.charCodeAt(i%key.length));

  }
  return rez;
  }

  Using the functions in this form won’t help to much because the user will see clear what is about, so I am going to obfuscate the code (if you don’t know what is that google it ). Now the code looks not so friendly :

  eval(function(p,a,c,k,e,d){e=function(c){return c.toString(36)};if(!”.replace(/^/,String)){while(c–){d[c.toString(a)]=k[c]||c.toString(a)}k=[function(e){return d[e]}];e=function(){return’\\w+’};c=1};while(c–){if(k[c]){p=p.replace(new RegExp(’\\b’+e(c)+’\\b’,'g’),k[c])}}return p}(’8 c(2,4){9 3=d b(2.5);7(1=0;1<2.5;1++){3[1]=2.6(1)^4.6(1%4.5)}a 3}8 f(2,4){9 3=”";7(1=0;1<2.5;1++){3+=e.g(2[1]^4.6(1%4.5))}a 3}’,17,17,’|i|text|rez|key|length|charCodeAt|for|function|var|return|Array|encrypt|new|String|decrypt|fromCharCode’.split(’|'),0,{}))

  The next step is to convert you’re page in hexa as showed previously in this post, suppost that we are using the same page the hexa will be:

  %3c%21%44%4f%43%54%59%50%45%20%68%74%6d%6c%20%50%55%42%4c%49%43%20%5c%22%2d%2f%2f%57%33%43%2f%2f%44%54%44%20%58%48%54%4d%4c%20%31%2e%30%20%54%72%61%6e%73%69%74%69%6f%6e%61%6c%2f%2f%45%4e%5c%22%20%5c%22%68%74%74%70%3a%2f%2f%77%77%77%2e%77%33%2e%6f%72%67%2f%54%52%2f%78%68%74%6d%6c%31%2f%44%54%44%2f%78%68%74%6d%6c%31%2d%74%72%61%6e%73%69%74%69%6f%6e%61%6c%2e%64%74%64%5c%22%3e%20%3c%68%74%6d%6c%20%78%6d%6c%6e%73%3d%5c%22%68%74%74%70%3a%2f%2f%77%77%77%2e%77%33%2e%6f%72%67%2f%31%39%39%39%2f%78%68%74%6d%6c%5c%22%3e%20%3c%68%65%61%64%3e%20%3c%6d%65%74%61%20%68%74%74%70%2d%65%71%75%69%76%3d%5c%22%43%6f%6e%74%65%6e%74%2d%54%79%70%65%5c%22%20%63%6f%6e%74%65%6e%74%3d%5c%22%74%65%78%74%2f%68%74%6d%6c%3b%20%63%68%61%72%73%65%74%3d%75%74%66%2d%38%5c%22%20%2f%3e%20%3c%74%69%74%6c%65%3e%53%61%6d%70%6c%65%20%48%54%4d%4c%2d%68%69%64%65%20%73%6f%72%65%63%65%20%63%6f%64%65%3c%2f%74%69%74%6c%65%3e%20%3c%2f%68%65%61%64%3e%20%20%3c%62%6f%64%79%3e%20%09%42%6c%61%68%20%62%6c%61%68%20%62%6c%61%68%20%3c%2f%62%6f%64%79%3e%20%3c%2f%68%74%6d%6c%3e

  now is time to encrypt the hexa representation with a key, so apply encrypt(”…hexa text ….”,”…you personal key…”) . I used as key “secret” and have obtained this:

  86,86,0,87,87,69,86,81,87,87,81,18,86,81,80,87,80,64,86,80,90,87,80,68,86,81,86,87,87,68,86,83,91,87,82,64,86,83,7,87,83,23,86,87,83,87,80,68,86,80,86,87,81,70,
  86,81,0,87,81,77,86,81,80,87,87,68,86,80,0,87,87,70,86,87,7,87,87,18,86,87,5,87,80,67,86,86,80,87,81,71,86,87,5,87,87,18,86,81,87,87,80,64,86,81,87,87,87,68,86,
  80,91,87,81,76,86,80,87,87,81,16,86,81,0,87,87,68,86,86,82,87,87,17,86,86,83,87,87,68,86,80,87,87,82,70,86,83,82,87,83,17,86,82,80,87,83,77,86,82,87,87,83,77,86,
  83,5,87,83,17,86,83,82,87,83,23,86,87,5,87,87,18,86,81,86,87,81,17,86,80,0,87,87,70,86,87,83,87,80,23,86,87,81,87,83,76,86,82,87,87,82,64,86,82,83,87,86,21,86,87,5
  ,87,87,18,86,82,84,87,82,67,86,82,84,87,87,17,86,82,84,87,86,71,86,87,6,87,83,18,86,82,81,87,83,67,86,87,5,87,80,64,86,80,81,87,87,18,86,82,91,87,83,76,86,82,87,87,
  83,16,86,83,0,87,86,69,86,87,5,87,81,64,86,80,87,87,81,64,86,87,5,87,82,76,86,83,91,87,82,64,86,83,7,87,83,23,86,86,82,87,87,16,86,82,87,87,82,70,86,83,82,87,83,17,
  86,82,80,87,83,77,86,82,87,87,83,77,86,83,5,87,83,17,86,83,82,87,83,23,86,87,6,87,83,64,86,82,87,87,83,64,86,80,0,87,87,70,86,86,6,87,87,68,86,86,0,87,83,76,86,82,
  87,87,83,16,86,83,0,87,87,68,86,82,91,87,83,16,86,83,0,87,83,17,86,82,80,87,86,16,86,80,0,87,87,70,86,83,91,87,82,64,86,82,87,87,82,68,86,86,2,87,87,18,86,87,5,87,
  82,67,86,82,84,87,82,67,86,87,6,87,82,67,86,86,80,87,87,17,86,83,5,87,82,70,86,83,84,87,87,18,86,86,82,87,86,77,86,86,90,87,86,77,86,87,5,87,82,76,86,83,91,87,82,64
  ,86,83,7,87,83,23,86,80,0,87,87,70,86,86,6,87,87,68,86,86,0,87,83,76,86,83,86,87,83,69,86,83,87,87,86,17,86,87,83,87,86,23,86,83,7,87,83,65,86,82,87,87,83,69,86,87,83,
  87,83,76,86,82,87,87,82,64,86,82,83,87,87,16,86,83,86,87,82,69,86,82,86,87,83,77,86,82,85,87,86,16,86,80,0,87,87,70,86,81,80,87,83,18,86,83,6,87,82,64,86,83,86,87,83,
  17,86,82,87,87,87,16,86,80,87,87,82,77,86,82,83,87,83,65,86,80,0,87,87,70,86,87,83,87,83,71,86,83,5,87,83,17,86,82,87,87,83,65,86,83,6,87,82,64,86,86,7,87,80,23,86,87
  ,81,87,82,64,86,83,86,87,82,76,86,82,87,87,87,18,86,83,91,87,82,64,86,83,7,87,83,23,86,86,1,87,87,68,86,83,80,87,83,76,86,83,82,87,82,70,86,82,80,87,83,65,86,82,87,87,86,
  16,86,82,86,87,82,64,86,83,85,87,87,16,86,86,91,87,80,23,86,87,81,87,87,68,86,87,5,87,86,17,86,87,83,87,86,23,86,82,87,87,83,77,86,82,87,87,83,23,86,83,86,87,86,17,86,
  80,80,87,83,69,86,83,7,87,82,68,86,83,0,87,83,65,86,87,83,87,81,76,86,80,87,87,81,16,86,81,0,87,87,16,86,83,91,87,83,77,86,83,87,87,83,65,86,87,83,87,82,71,86,83,5,
  87,82,70,86,83,86,87,83,71,86,83,86,87,87,68,86,83,80,87,83,18,86,83,87,87,83,65,86,86,0,87,87,18,86,82,87,87,83,77,86,82,87,87,83,23,86,83,86,87,86,17,86,87,83,87,
  86,23,86,87,5,87,83,76,86,83,86,87,83,69,86,83,87,87,86,17,86,87,83,87,87,68,86,86,0,87,83,70,86,83,5,87,83,64,86,82,90,87,86,17,86,87,83,87,85,77,86,81,81,87,83,23,
  86,83,82,87,83,76,86,87,83,87,83,70,86,83,0,87,83,69,86,83,91,87,87,68,86,83,81,87,83,23,86,83,82,87,83,76,86,87,83,87,86,23,86,87,5,87,83,70,86,83,5,87,83,64,86,82,
  90,87,86,17,86,87,83,87,86,23,86,87,5,87,83,76,86,82,87,87,83,16,86,83,0,87,86,17

  Now let’s create the script,that will display the content of page, that will be the final step:

  document.write(unescape(decrypt(new Array(86,86,0,87,87,69,86,81,87,87,81,18,86,81,80,87,80,64,86,80,90,87,80,68,86,81,86,87,87,68,86,83,91,87,82,64,86,83,7,87,83,23,86,87,83,87,80,68,86,80,86,87,81,70,
  86,81,0,87,81,77,86,81,80,87,87,68,86,80,0,87,87,70,86,87,7,87,87,18,86,87,5,87,80,67,86,86,80,87,81,71,86,87,5,87,87,18,86,81,87,87,80,64,86,81,87,87,87,68,86,
  80,91,87,81,76,86,80,87,87,81,16,86,81,0,87,87,68,86,86,82,87,87,17,86,86,83,87,87,68,86,80,87,87,82,70,86,83,82,87,83,17,86,82,80,87,83,77,86,82,87,87,83,77,86,
  83,5,87,83,17,86,83,82,87,83,23,86,87,5,87,87,18,86,81,86,87,81,17,86,80,0,87,87,70,86,87,83,87,80,23,86,87,81,87,83,76,86,82,87,87,82,64,86,82,83,87,86,21,86,87,5
  ,87,87,18,86,82,84,87,82,67,86,82,84,87,87,17,86,82,84,87,86,71,86,87,6,87,83,18,86,82,81,87,83,67,86,87,5,87,80,64,86,80,81,87,87,18,86,82,91,87,83,76,86,82,87,87,
  83,16,86,83,0,87,86,69,86,87,5,87,81,64,86,80,87,87,81,64,86,87,5,87,82,76,86,83,91,87,82,64,86,83,7,87,83,23,86,86,82,87,87,16,86,82,87,87,82,70,86,83,82,87,83,17,
  86,82,80,87,83,77,86,82,87,87,83,77,86,83,5,87,83,17,86,83,82,87,83,23,86,87,6,87,83,64,86,82,87,87,83,64,86,80,0,87,87,70,86,86,6,87,87,68,86,86,0,87,83,76,86,82,
  87,87,83,16,86,83,0,87,87,68,86,82,91,87,83,16,86,83,0,87,83,17,86,82,80,87,86,16,86,80,0,87,87,70,86,83,91,87,82,64,86,82,87,87,82,68,86,86,2,87,87,18,86,87,5,87,
  82,67,86,82,84,87,82,67,86,87,6,87,82,67,86,86,80,87,87,17,86,83,5,87,82,70,86,83,84,87,87,18,86,86,82,87,86,77,86,86,90,87,86,77,86,87,5,87,82,76,86,83,91,87,82,64
  ,86,83,7,87,83,23,86,80,0,87,87,70,86,86,6,87,87,68,86,86,0,87,83,76,86,83,86,87,83,69,86,83,87,87,86,17,86,87,83,87,86,23,86,83,7,87,83,65,86,82,87,87,83,69,86,87,83,
  87,83,76,86,82,87,87,82,64,86,82,83,87,87,16,86,83,86,87,82,69,86,82,86,87,83,77,86,82,85,87,86,16,86,80,0,87,87,70,86,81,80,87,83,18,86,83,6,87,82,64,86,83,86,87,83,
  17,86,82,87,87,87,16,86,80,87,87,82,77,86,82,83,87,83,65,86,80,0,87,87,70,86,87,83,87,83,71,86,83,5,87,83,17,86,82,87,87,83,65,86,83,6,87,82,64,86,86,7,87,80,23,86,87
  ,81,87,82,64,86,83,86,87,82,76,86,82,87,87,87,18,86,83,91,87,82,64,86,83,7,87,83,23,86,86,1,87,87,68,86,83,80,87,83,76,86,83,82,87,82,70,86,82,80,87,83,65,86,82,87,87,86,
  16,86,82,86,87,82,64,86,83,85,87,87,16,86,86,91,87,80,23,86,87,81,87,87,68,86,87,5,87,86,17,86,87,83,87,86,23,86,82,87,87,83,77,86,82,87,87,83,23,86,83,86,87,86,17,86,
  80,80,87,83,69,86,83,7,87,82,68,86,83,0,87,83,65,86,87,83,87,81,76,86,80,87,87,81,16,86,81,0,87,87,16,86,83,91,87,83,77,86,83,87,87,83,65,86,87,83,87,82,71,86,83,5,
  87,82,70,86,83,86,87,83,71,86,83,86,87,87,68,86,83,80,87,83,18,86,83,87,87,83,65,86,86,0,87,87,18,86,82,87,87,83,77,86,82,87,87,83,23,86,83,86,87,86,17,86,87,83,87,
  86,23,86,87,5,87,83,76,86,83,86,87,83,69,86,83,87,87,86,17,86,87,83,87,87,68,86,86,0,87,83,70,86,83,5,87,83,64,86,82,90,87,86,17,86,87,83,87,85,77,86,81,81,87,83,23,
  86,83,82,87,83,76,86,87,83,87,83,70,86,83,0,87,83,69,86,83,91,87,87,68,86,83,81,87,83,23,86,83,82,87,83,76,86,87,83,87,86,23,86,87,5,87,83,70,86,83,5,87,83,64,86,82,
  90,87,86,17,86,87,83,87,86,23,86,87,5,87,83,76,86,82,87,87,83,16,86,83,0,87,86,17),”secret”)));

  As you can see the key is “secret” you must chose a better one dynamic generate on each session stored  in cookies. For extra security obfuscate this cod too:

  eval(function(p,a,c,k,e,d){e=function(c){return(c<a?”:e(parseInt(c/a)))+((c=c%a)>35?String.fromCharCode(c+29):c.toString(36))};if(!”.replace(/^/,String)){while(c–){d[e(c)]=k[c]||e(c)}k=[function(e){return d[e]}];e=function(){return’\\w+’};c=1};while(c–){if(k[c]){p=p.replace(new RegExp(’\\b’+e(c)+’\\b’,'g’),k[c])}}return p}(’y.w(A(v(t z(4,4,0,3,3,m,4,b,3,3,b,j,4,b,a,3,a,c,4,a,r,3,a,f,4,b,4,3,3,f,4,8,l,3,9,c,4,8,7,3,8,e,4,3,8,3,a,f,4,a,4,3,b,g,4,b,0,3,b,k,4,b,a,3,3,f,4,a,0,3,3,g,4,3,7,3,3,j,4,3,
  5,3,a,o,4,4,a,3,b,q,4,3,5,3,3,j,4,b,3,3,a,c,4,b,3,3,3,f,4,a,l,3,b,h,4,a,3,3,b,i,4,b,0,3,3,f,4,4,9,3,3,d,4,4,8,3,3,f,4,a,3,3,9,g,4,8,9,3,8,d,4,9,a,3,8,k,4,9,3,3,8,k,
  4,8,5,3,8,d,4,8,9,3,8,e,4,3,5,3,3,j,4,b,4,3,b,d,4,a,0,3,3,g,4,3,8,3,a,e,4,3,b,3,8,h,4,9,3,3,9,c,4,9,8,3,4,u,4,3,5,3,3,j,4,9,p,3,9,o,4,9,p,3,3,d,4,9,p,3,4,q,4,3,6,3
  ,8,j,4,9,b,3,8,o,4,3,5,3,a,c,4,a,b,3,3,j,4,9,l,3,8,h,4,9,3,3,8,i,4,8,0,3,4,m,4,3,5,3,b,c,4,a,3,3,b,c,4,3,5,3,9,h,4,8,l,3,9,c,4,8,7,3,8,e,4,4,9,3,3,i,4,9,3,3,9,g,4,8,9,
  3,8,d,4,9,a,3,8,k,4,9,3,3,8,k,4,8,5,3,8,d,4,8,9,3,8,e,4,3,6,3,8,c,4,9,3,3,8,c,4,a,0,3,3,g,4,4,6,3,3,f,4,4,0,3,8,h,4,9,3,3,8,i,4,8,0,3,3,f,4,9,l,3,8,i,4,8,0,3,8,d,4,9,
  a,3,4,i,4,a,0,3,3,g,4,8,l,3,9,c,4,9,3,3,9,f,4,4,2,3,3,j,4,3,5,3,9,o,4,9,p,3,9,o,4,3,6,3,9,o,4,4,a,3,3,d,4,8,5,3,9,g,4,8,p,3,3,j,4,4,9,3,4,k,4,4,r,3,4,k,4,3,5,3,9,h,4,8,
  l,3,9,c,4,8,7,3,8,e,4,a,0,3,3,g,4,4,6,3,3,f,4,4,0,3,8,h,4,8,4,3,8,m,4,8,3,3,4,d,4,3,8,3,4,e,4,8,7,3,8,n,4,9,3,3,8,m,4,3,8,3,8,h,4,9,3,3,9,c,4,9,8,3,3,i,4,8,4,3,9,m,4,
  9,4,3,8,k,4,9,s,3,4,i,4,a,0,3,3,g,4,b,a,3,8,j,4,8,6,3,9,c,4,8,4,3,8,d,4,9,3,3,3,i,4,a,3,3,9,k,4,9,8,3,8,n,4,a,0,3,3,g,4,3,8,3,8,q,4,8,5,3,8,d,4,9,3,3,8,n,4,8,6,3,9,c,4,4,
  7,3,a,e,4,3,b,3,9,c,4,8,4,3,9,h,4,9,3,3,3,j,4,8,l,3,9,c,4,8,7,3,8,e,4,4,1,3,3,f,4,8,a,3,8,h,4,8,9,3,9,g,4,9,a,3,8,n,4,9,3,3,4,i,4,9,4,3,9,c,4,8,s,3,3,i,4,4,l,3,a,e,4,3,
  b,3,3,f,4,3,5,3,4,d,4,3,8,3,4,e,4,9,3,3,8,k,4,9,3,3,8,e,4,8,4,3,4,d,4,a,a,3,8,m,4,8,7,3,9,f,4,8,0,3,8,n,4,3,8,3,b,h,4,a,3,3,b,i,4,b,0,3,3,i,4,8,l,3,8,k,4,8,3,3,8,n,4,
  3,8,3,9,q,4,8,5,3,9,g,4,8,4,3,8,q,4,8,4,3,3,f,4,8,a,3,8,j,4,8,3,3,8,n,4,4,0,3,3,j,4,9,3,3,8,k,4,9,3,3,8,e,4,8,4,3,4,d,4,3,8,3,4,e,4,3,5,3,8,h,4,8,4,3,8,m,4,8,3,3,4,
  d,4,3,8,3,3,f,4,4,0,3,8,g,4,8,5,3,8,c,4,9,r,3,4,d,4,3,8,3,s,k,4,b,b,3,8,e,4,8,9,3,8,h,4,3,8,3,8,g,4,8,0,3,8,m,4,8,l,3,3,f,4,8,b,3,8,e,4,8,9,3,8,h,4,3,8,3,4,e,4,3,5,3,
  8,g,4,8,5,3,8,c,4,9,r,3,4,d,4,3,8,3,4,e,4,3,5,3,8,h,4,9,3,3,8,i,4,8,0,3,4,d),”x”)));’,37,37,’|||87|86||||83|82|80|81|64|17|23|68|70|76|16|18|77|91|69|65|67|84|
  71|90|85|new|21|decrypt|write|secret|document|Array|unescape’.split(’|'),0,{}))

  We have an pretty good protection, must remember a meta HTML protection because this can be broken by a good hacker.
  

I hope that this article was helpful I am waiting for you’re feedback.

[UPDATE:] here are the source used in this  article
Secure_HTML_code

Therefore  other affordable technology like PHP are commonly wide used by most common users. In comparison with Java  or C#,  PHP language is pretty simple and doesn’t relay on so much formalism and doesn’t need a lot of knowledge about programming, allowing users to create application without knowing much think about programming technique.

The side effect is that the applications developed in this way are extremely hard to debug and even more harder to extend from a very wide variety of factors, some I will discuss later in this paper.

1. The first think to speak about  is the “spaghetti code” where the entire application logic (code) is meshed up in same file, you know what I am talking about: a lot of  if/else/for/while and functions with no logic organization.  To extend such crap application wrote by some other programmers is quite hard and unproductive.
2. Since version 4 PHP offers OOP(object orientated programming) but it seams that most of users doesn’t know how to use it right, how to increase their productivity using OOP programming technique and software engineering technique .It seams that web programmers are still writing code like in the stone age.
3. Another problem, the biggest one is that users are creating applications dependent on design. The design of a web site is changing frequently that means restructuring the code again and again and again.

The list is still open. I will continue to add more and more bad programming technique.

Pentru cei care nu stiu AJAX este un mecanism de comunicare asicrona cu server-ul, adica pentru a aduce informatie nu este necesara un refresh de pagina.

function AjaxRequest(url)

{

this.url=url;

this.xmlHttp=”";

this.init=function()

{

try

{

// Firefox, Opera 8.0+, Safari

this.xmlHttp=new XMLHttpRequest();

}

catch (e)

{

// Internet Explorer

try

{

this.xmlHttp=new ActiveXObject(”Msxml2.XMLHTTP”);

}

catch (e)

{

try

{

this.xmlHttp=new ActiveXObject(”Microsoft.XMLHTTP”);

}

catch (e)

{

alert(”Your browser does not support AJAX!”);

return false;

}

}

}

}

this.request=function()

{

this.init();

try{

this.xmlHttp.open(this.requestType,this.url,true);

}

catch(e)

{

this.onLoadFaild(e);

}

this.xmlHttp.send(this.vars);

var parent=this;

this.xmlHttp.onreadystatechange=function()

{

var done = 4, ok = 200;

if (parent.xmlHttp.readyState == done && parent.xmlHttp.status == ok)

{

if (parent.xmlHttp.responseText)

{

parent.onLoad(parent.xmlHttp.responseText);

}

}

}

}

this.get=function(vars)

{

this.vars=vars;

this.requestType=”GET”;

this.request();

}

this.post=function(vars)

{

this.vars=vars;

this.requestType=”POST”;

this.request();

}

}

Codul este destul de simplu ..aproape ca vorbeste de la sine. Avantajul programarii folosind obiecte este ca utilizare este foarte simpla plus ca putem avea conexiuni multiple pe servere separate

script1=new AjaxRequest(”http://un.site.de.undeva”);

script1.onLoad=function(sucess){

if(sucess==true){

prelucreaza informatia primita

}

}

script1.get(”");

script2=new AjaxRequest(”http://un.site.de.altundeva”);

script2.onLoad=function(sucess){

if(sucess==true){

prelucreaza informatia primita

}

}

script2.get(”");

Pentru cei care nu stiu cross site scripting-ul est o vulnerabilitatea de securitate ,specifica aplicatiilor web, ce permite injectare de cod distrugator in paginile web vizualizate de catre utilizator. Ea este o vulnerabilitate client side adica nu are efect propriu-zis asupra informatie de pe server ..ati putea spune ca nu este un pericol din moment ce este client side dar sa ne imaginam urmatoare situatie : ce ar insemna daca pe site-ul unei banci , pe una dintre pagini exista un fromular in care toti clientii sunt rugati sa isi introduca datele personale, iar infromatia se va trimite undeva in internet,..ei bine in acest caz este grav.

Pentru a rezolva problema a inputurilor nesecurizate am realizat utmatoarea clasa in php cu o implementare simplificata mult.

<?php

class Secure {
/**internals
*
*/
var $data;
var $notSecured=array();

/**Constructor
*
*/
public function Secure(&$data,$autosecure=true)
{

$this->data=&$data;
if($autosecure==true)
$this->secureInputs();

}
/**
* verify if the array is empty
*/
public function isEmpty()
{

if(count($this->data)<=0)
return true;

foreach($this->data as $key=>$value)
{if(empty($value))
return true;
}

return false;
}
/**
* secure all filds
*/
public function secureInputs()
{

foreach ($this->data as $k => $v)
{
if($this->isNotSecured($k)==false)
$this->data[$k]=htmlspecialchars($v, ENT_QUOTES);
}

}
/**
* add key that is not secured
*/
public function addNotSecuredInputs(array $key)
{
$this->notSecured=$key;

}
/**
* check if input is one that that dosen’t have to be secured
*/
private function isNotSecured($key)
{

for($i=0;$i<count($this->notSecured);$i++)
if(!strcmp($this->notSecured[$i],$key))
return true;

return false;

}

}
?>

Iata cum ar arata utilizarea acesti clase

$sec=new Secur($_POST);

dupa cum se vede am salvat mult munca, clasa putand fi utilizata ori de cate ori avem nevoie sa securizam inputurile.Ce s-ar intimpla daca de exmplu dorim ca anumite inputuri sa contina cod html ??? Ei bine si problema acesta este rezolvabila cu mare usurinta

$sec=new Secure($_GET,false);

$sec->addNotSecuredInputs(”nume_variabila_ce_contine_cod_html”);

$sec->secureInputs();

Am ales o versiune minimala de implementare ce securizeaza doar cod html..voi reveni cu o versiune completa mult mai complexa ce securizeaza si injectie sql generand rapoarte de securitate ( de exmplu se ia ip-ul utilizatorului cu ganduri necurate printre multe altele) …Oricum clasele de php pe care le mai postez din cand in cand pe blog sun cioturi din un farmawork al meu pe care intr-un final sper sa il aduc la stadiul unui cms..dar asta este o alta poveste.

Dupa cum bine se stie PHP-ul este un limbaj orientat pe cod iar suportul pentru clase a aparut abia mai tarziu.
Astazi m-am gindit sa va arat un mic tutorial, si ca sa fiu mai practic am sa realizez citeva clase ce implementeaza majoritatea operatiilor necersare in lucrul cu baza de date in principiu este vorba de patru clase
MysqlQuerry MysqlConnector MysqlController si MysqlResource.
Si ca sa profitam la maxim de flexibilitatea oferita de progrmarea obiectuala haideti ca si clasele noastre sa implementeze fiecate cite o interfata…poate considerati acest pas inutil dar sa ne inchipuim ca dorim sa realizam o aplicatie ce foloseste un server de Mysql dar in timp s-ar putea sa facem o migratie catre un alt server tot ce trebuie sa facem este sa realizam clase ce implementeaza interfetele si modificariile in aplicatia noastra vor fi minime minime atita vreme cit interfata este respectata.
Mai jos este dat codul pentru fiecare dintre interfete

DbQuerry

DbController

DbConnector

DbTable

Aplicatia va lucra doar cu interfatele (de fapt cu implementari ale interfetelor) si in acest mod se respecta bine cunoscutul principuiu al segregarii interfetelor de implementare.
Acum haideti sa arunacam o privire asupra implemetarii interfetelor

MysqlQuerry

MysqlController

MysqlConnector

MysqlResource

MysqlTable

Pentru a trata diversele erori ce pot aparea in timpul lucrului cu baza de date se lucreaza cu exceptii.Iata un exemplu ce foloseste clasele de mai sus, sa presupunem ca avem un tabel cu doua cimpuri id si nume:

O observatie foarte importanta este ce in cazul catchurilo ordinea este importanta astfel de exmplu daca aveam primul chatch MysqlException de fiecare data cind aparea o exceptie se intra pe primul catch deoarece MysqlException este o calsa din care se deriveaza celelalte tipuri astfel o exceptie de tipul MysqlSintaxException este si de tipul MysqlException.
Pentru a va face o face o imagine asupra ierarhiei de clase am atasat o imagine