12 Tips to Maintain a Virus Free Computer.

         



  

Is your computer infected with virus? Do you often get mysterious error messages? Well this is a common problem faced by almost all the computer users across the globe. There are many viruses and worms out there that could infect your computer. Some are harmless, but, they do have the capacity to do any number of nasty things, up to and including, erasing all data from your computer. However there are ways to keep viruses away from your PC. Here are the 12 tips to maintain a virus free computer.
1. Email is one of the common ways by which your computer can catch a virus. So it is always recommended to stay away from SPAM. Open only those emails that has it’s origin from a trusted source such as those which comes from your contact list. If you are using your own private email host (other than gmail, yahoo, hotmail etc.) then it is highly recommended that you use a good anti-spam software. And finally NEVER click on any links in the emails that comes from untrusted sources.
2. USB thumb/pen drives is another common way by which viruses spread rapidly. So it is always a good habit to perform a virus scan before copying any data onto your computer. NEVER double-click the pen drive to open it. Instead right-click on it and select the option “open”. This is a safe way to open a pen drive.
3. Be careful about using MS Outlook. Outlook is more susceptible to worms than other e-mail programs, unless you have efficient Anti-Virus programs running. Use Pegasus or Thunderbird (by Mozilla), or a web-based program such as Hotmail or Yahoo (In Firefox).
4. As we all know, Internet is the main source of all the malicious programs including viruses, worms, trojans etc. In fact Internet contributes to virus infection by up to 80%. So here are the tips for safe surfing habits so that you can ward off virus infection up to the maximum extent.
• Don’t click on pop-up windows that announce a sudden disaster in your city or announce that you’ve won an hourly prize. They are the ways to mislead Internet users and you should never trust them.
• You can also use a pop-up blocker to automatically block those pop-ups.
5. Most of us use search engines like Google to find what we are looking for. It is quite obvious for a malicious website to get listed in the search results. So to avoid visiting those untrusted malicious websites, you can download and install the AVG LinkScanner which is a freeware. This tool can become very handy and will help you to stay away from malicious websites.
6. Install a good antivirus software and keep it updated. Also perform full system scan periodically. It is highly recommended that you turn on the automatic update feature. This is the most essential task to protect your PC from virues. If PC security is your first option then it is recommended that you go for a shareware antivirus software over the free ones. Most of the antivirus supports the Auto-Protect feature that provides realtime security for your PC. Make sure that this feature is turned on.
7. Install a good Antispyware program, that operates against Internet malware and spyware.
8. Never open any email attachments that come from untrusted sources. If it is a picture, text or sound file (these attachments end in the extensions .txt, .jpeg, .gif, .bmp, .tif, .mp3, .htm, .html, and .avi), you are probably safe, but still do a scan before opening.
9. Do not use disks that other people gave you, even from work. The disk could be infected with a virus. Of course, you can run a virus scan on it first to check it out.
10. Set up your Windows Update to automatically download patches and upgrades. This will allow your computer to automatically download any updates to both the operating system and Internet Explorer. These updates fix security holes in both pieces of software.
11. While you download files from untrusted websites/sources such as torrents, warez etc. make sure that you run a virus scan before executing them.
12. And finally it is recommended not to visit the websites that feature illegal/unwanted stuffs such as cracks, serials, warez etc. since they contribute much in spreading of viruses and other malicious programs.
-anurag guleria-

What are Public IP & Private Ip Addresses.

Internet Protocol (IP) addresses are usually of two types: Public and Private. If you have ever wondered to know what is the difference between a public and a private IP address, then you are at the right place. In this post I will try to explain the difference between a public and a private IP address in layman’s terms so that it becomes simple and easy to understand.
What are Public IP Addresses?
A public IP address is assigned to every computer that connects to the Internet where each IP is unique. Hence there cannot exist two computers with the same public IP address all over the Internet. This addressing scheme makes it possible for the computers to “find each other” online and exchange information. User has no control over the IP address (public) that is assigned to the computer. The public IP address is assigned to the computer by the Internet Service Provider as soon as the computer is connected to the Internet gateway.
A public IP address can be either static or dynamic. A static public IP address does not change and is used primarily for hosting WebPages or services on the Internet. On the other hand a dynamic public IP address is chosen from a pool of available addresses and changes each time one connects to the Internet. Most Internet users will only have a dynamic IP assigned to their computer which goes off when the computer is disconnected from the Internet. Thus when it is re-connected it gets a new IP.
You can check your public IP address by visiting www.whatismyip.com
What are Private IP Addresses?
An IP address is considered private if the IP number falls within one of the IP address ranges reserved for private networks such as a Local Area Network (LAN). The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private networks (local networks):
10.0.0.0 – 10.255.255.255 (Total Addresses: 16,777,216)
172.16.0.0 – 172.31.255.255 (Total Addresses: 1,048,576)
192.168.0.0 – 192.168.255.255 (Total Addresses: 65,536)
Private IP addresses are used for numbering the computers in a private network including home, school and business LANs in airports and hotels which makes it possible for the computers in the network to communicate with each other. Say for example, if a network X consists of 10 computers each of them can be given an IP starting from 192.168.1.1 to 192.168.1.10. Unlike the public IP, the administrator of the private network is free to assign an IP address of his own choice (provided the IP number falls in the private IP address range as mentioned above).
Devices with private IP addresses cannot connect directly to the Internet. Likewise, computers outside the local network cannot connect directly to a device with a private IP. It is possible to interconnect two private networks with the help of a router or a similar device that supports Network Address Translation.
If the private network is connected to the Internet (through an Internet connection via ISP) then each computer will have a private IP as well as a public IP. Private IP is used for communication within the network where as the public IP is used for communication over the Internet. Most Internet users with a DSL/ADSL connection will have both a private as well as a public IP.
You can know your private IP by typing ipconfig command in the command prompt. The number that you see against “IPV4 Address:” is your private IP which in most cases will be 192.168.1.1 or 192.168.1.2. Unlike the public IP, private IP addresses are always static in nature.
Unlike what most people assume, a private IP is neither the one which is impossible to trace (just like the private telephone number) nor the one reserved for stealth Internet usage. In reality there is no public IP address that is impossible to trace since the protocol itself is designed for transperancy.
-anurag guleria-

What are Input Validation Attacks ?

Input Validation Attacks :-

Input Validation Attacks are where an attacker intentionally sends unusual input in the hopes of confusing the application.
The most common input validation attacks are as follows-
1) Buffer Overflow :- Buffer overflow attacks are enabled due to sloppy programming or mismanagement of memory by the application developers. Buffer overflow may be classified into stack overflows, format string overflows, heap overflows and integer overflows. It may possible that an overflow may exist in language’s (php, java, etc.) built-in functions.
To execute a buffer overflow attack, you merely dump as much data as possible into an input field. The attack is said to be successful when it returns an application error. Perl is well suited for conducting this type of attack.
Here’s the buffer test, calling on Perl from the command line:
$ echo –e “GET /login.php?user=\
> `perl –e ‘print “a” x 500’`\nHTTP/1.0\n\n” | \
nc –vv website 80
This sends a string of 500 “a” characters for the user value to the login.php file.
Buffer overflow can be tested by sending repeated requests to the application and recording the server’s response.
2) Canonicalization :- These attacks target pages that use template files or otherwise reference alternate files on the web server. The basic form of this attack is to move outside of the web document root in order to access system files, i.e., “../../../../../../../../../boot.ini”. This type of functionality is evident from the URL and is not limited to any one programming language or web server. If the application does not limit the types of files that it is supposed to view, then files outside of the web document root are targeted, something like following-
/menu.asp?dimlDisplayer=menu.asp
/webacc?User.asp=login.htt
/SWEditServlet?station_path=Z&publication_id=2043&template=login.tem
/Getfile.asp?/scripts/Client/login.js
/includes/printable.asp?Link=customers/overview.htm
3) Cross-site Scripting (XSS) :- Cross-site scripting attacks place malicious code, usually JavaScript, in locations where other users see it. Target fields in forms can be addresses, bulletin board comments, etc.
We have found that error pages are often subject to XSS attacks. For example, the URL for a normal application error looks like this:
http://website/inc/errors.asp?Error=Invalid%20password
This displays a custom access denied page that says, “Invalid password”. Seeing a string
on the URL reflected in the page contents is a great indicator of an XSS vulnerability. The attack would be created as:
http://website/inc/errors.asp?Error=<script%20src=…
That is, place the script tags on the URL.
4) SQL Injection :- This kind of attack occurs when an attacker uses specially crafted SQL queries as an input, which can open up a database. Online forms such as login prompts, search enquiries, guest books, feedback forms, etc. are specially targeted.
The easiest test for the presence of a SQL injection attack is to append “or+1=1” to the URL and inspect the data returned by the server.
example:- http://www.domain.com/index.asp?querystring=sports’ or 1=1–