TCP/IP Firewall

The combined set of protocols is called the Transmission Control Protocol and Internet Protocol TCP/IPprotocol suite.

As a network administrator, it is important that you understand the nature of potential attacks on computer security. We'll briefly describe the most important types of attacks so that you can better understand precisely what the Linux IP firewall will protect you against. You should do some additional reading to ensure that you are able to protect your network against other types of attacks. Here are some of the more important methods of attack and ways of protecting yourself against them:

Unauthorized access

This simply means that people who shouldn't be allowed to use your computer services are able to connect to and use them. For example, people outside your company might try to connect to your company accounting host or to your NFS server.

There are various ways to avoid this attack by carefully specifying who can gain access through these services. You can prevent network access to all except the intended users.

A malicious person who gains access to a computer system may guess system passwords or exploit the bugs and idiosyncratic behavior of certain programs to obtain a working account on that host.

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Network Security Configuration

Installed your Linux system, you should keep some basic security measures to protect your system

Firewalls, intrusion protection, encryption, data integrity, and authentication are ways of protecting against such attacks.

• A firewall prevents any direct unauthorized attempts at access.
• Intrusion detection checks the state of your system files to see if they have been tampered with by someone who has broken in.
• Encryption protects transmissions by authorized remote users, providing privacy.
• Integrity checks such as modification digests guarantee that messages and data have not been intercepted and changed or substituted en route.
• Authentication methods such as digital signatures can verify that the user claiming to send a message or access your system is actually that person.
  
  
  system is also a gateway for a private network, the system's firewall capability can effectively protect the network from outside attacks.
  
  Linux security- the ones with which every user has experience are passwords and file permissions.

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Linux Software websites

 Linux Software websites

Internet Sites	Description
ftp.redhat.com	Red Hat distribution RPM packages
rpmfind.net	RPM package repository
sourceforge.net	Source Forge open source software repository and development site
freshmeat.net	New Linux software
apps.kde.com	KDE software applications
www.gnome.org	GNOME software applications

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Advanced Database Techniques

PEAR DB is the database primitives shown earlier; it provides several shortcut functions for fetching result rows, as well as a unique row ID system and separate prepare/execute steps that can improve the performance of repeated queries.

$result_set = $db->query(SQL, values);

 Pass the query( ) function SQL with 
 in place of specific values, and add a second parameter consisting of 
the array of values to insert into the SQL 

When issuing the same query repeatedly, it can be more efficient to compile the query once and then execute it multiple times, using the prepare( ) , execute( ), and executeMultiple( ) methods.

$com = $db->prepare(SQL);

This returns a com query object. The execute( ) method fills in any placeholders in the query.

PEAR DB gives a lot of methods that perform a query and fetch the results in one step:  

getOne( ) , getRow( ), getCol( ), getAssoc( ), and getAll( ). 

$value-set = $db->getOne(SQL [, values ]);

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php-static variables

A static variable retains its value between calls to a function but is visible only within that function.
IT declare a variable static with the static keyword.

function test_counter (  ) {
  static $counter = 0;
  $counter++;
  echo "Static counter is now $counter\n";
}
$counter = 5;
test_counter(  );
test_counter(  );
echo "Global counter is $counter\n";
Static counter is now 1
Static counter is now 2
Global counter is 5

Variables declared outside a function are global.

 That is, they can be accessed from any part of the script. By default, 

they are not available inside functions.

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trade people use Google

Google is popular anywhere
Google's free online language translation service provides a knowledgeable support staff.
you can share a lot of  things With Google+ like  events,games, photos.
ITs  Find all businesses,online classifieds,advertising classifieds.Google takes a 67%
share of the U.S. search market.

Job growth is increased by this google even search job,employment,business grows with the
help of google.

Google’s Picasa Web Albums to store photos,and manage the photos very nice.
With these tools, you can create different versions of your profile .

Google Docs  store many things like  the latest doc,text files, more updates new files.

Gmail: Email from Google

Google Groups

 Google+

Google Translate

 Google News

Google Toolbar

 Google Docs

Google Finance

Picasa

Google - YouTube

 Google Checkout

Google Sites

Android Apps on Google

 

• Google Documents:- Share and add,edit documents , see them on the run with Google Docs mobile service, and take Google Notebook for web research.
• Google Spreadsheets:- Add live data to spreadsheets, and  charts and tables you can embed in web pages.
• Google Presentations:- See them on a mobile phone and save them as video.
• Gmail:- Send email to and from a mobile phone, adjust Gmail's layout with a style sheet, and a lot more
• iGoogle:- Create your own gadgets, program a screenscraper, add Flash games, and more.
• Google Calendar:- Add web content events, public calendars, and your Outlook Calendar to this application.
• Google Reader, Google Maps, Google Earth, and Google SketchUp:- the new 3D modeling software tool.
• Picasa, YouTube, and Google Video:-- customize and use these media management apps.

 

 

 

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Php Operators

PHP Operators The following table lists the operators from highest to lowest precedence. Operators A !, ~, ++, --, @ Right *, /, % Left +, -, . Left <<, >> Left <, <=, >=, > Nonassociative ==, !=, ===, !== Nonassociative & Left ^ Left | Left && Left || Left ? : (conditional operator) Left =, +=, -=, *=, /=, %=, ^=, .=, &=, |=, <<=, >>= Left AND Left XOR Left OR Left

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Php Networking Functions

There are many functions in php to convert or look up domain name, IP address,
protocol, and service information.

Domain name/IP address lookups and conversions

• gethostbynamel()
• gethostbyname()
• gethostbyaddr()
• ip2long()
• long2ip()

 Sockets

• fsockopen()
• pfsockopen()
• socket_get_status()
• socket_set_blocking()
• socket_set_timeout()
  
  
  DNS resource records
  
  
  • checkdnsrr()
  • getmxrr()
   

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php-Error Control Operators

PHP gives one error control operator: the at sign (@).Any error messages that might be generated by that expression will be ignored.

If you have set a custom error handler function with set_error_handler() then it will still get called, but this custom error handler can call error_reporting() which will return 0 when the call that triggered the error was preceded by an @. 

<?php/* Intentional file error */$test_file = @file ('no_existent_file') or
    die ("Failed opening file: error was '$php_errormsg'");
// this works for any expression, not just functions:$val22 = @$cache[$key];// will not issue a notice if the index $key doesn't exist.
?> 

 

or  

add  error_reporting()  in the script

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how to creating a Web Site

To create your own Web site, you need access to a Web server. Red Hat automatically installs the Apache Web server on its Linux systems. You can also rent Web page space on a remote server—a service many ISPs provide, some for free. On Red Hat systems, the directory set up by your Apache Web server for your Web site pages is /var/httpd/html. Other servers provide you with a directory for your home page. Place the Web pages you create in that directory. You place your home page here. You can make other subdirectories with their own Web pages to which these can link. Web pages are not difficult to create. Links from one page to another move users through your Web site. You can even create links to Web pages or resources on other sites. Many excellent texts are available on Web page creation and management.

Web pages are created using either HTML intro, the Hypertext Markup Language, or the newer extended version, XML, the Extended Markup Language. They are a subset of Standard Generalized Markup Language (SGML). Creating an HTML or XML document is a matter of inserting HTML or XML tags in a text file. In this respect, creating a Web page is as simple as using a tag-based word processor. You use the HTML tags to format text for display as a Web page. XML tags can include more detailed information about a particular connection such as object data or transaction characteristics. The Web page itself is a text file you can create using any text editor. If you are familiar with tag-based word processing on Unix systems, you will find it conceptually similar to nroff. Some HTML tags indicate headings, lists, and paragraphs, as well as links to reference Web resources.

Instead of manually entering HTML or XML code, you can use Web page composers. A Web page composer provides a graphical interface for constructing Web pages. Special Web page creation programs can easily help you create complex Web pages without ever having to type any HTML tags explicitly. Remember, though, no matter what tool you use to create your Web page, the Web page itself will be an HTML document.

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