Advance Network Security

Network Security

Let's First of all have a look at all those problem that creates a hurdle in our security. We will summarize them here shortly. then we will carry on in detail about each problem. how to solve them, how to counter them. Also we must understand the is need of security because the information we store is a valuable asset for us. We might take help of information security services like: 

• Confidentiality
• Maintaining the privacy of data
• Integrity
• Detecting that the data is not tampered with
• Authentication
• Establishing proof of identity
• Nonrepudiation
• Ability to prove that the sender actually sent the data
• Access Control
• Access to information resources are regulated
• Availability
• Computer assets are available to authorized parties when needed

Security Problems

  n   Computer networks are typically a shared resource used by many applications representing different interests.

n   The Internet is particularly widely shared, being used by competing businesses, mutually antagonistic governments, and opportunistic criminals.

n   Unless security measures are taken, a network conversation or a distributed application may be compromised by an adversary.

n   Consider some threats to secure use of, for example, the World Wide Web.

n  Suppose you are a customer using a credit card to order an item from a website.

n  An obvious threat is that an adversary would eavesdrop on your network communication, reading your messages to obtain your credit card information.

n  It is possible and practical, however, to encrypt messages so as to prevent an adversary from understanding the message contents. A protocol that does so is said to provide confidentiality.

n  Taking the concept a step farther, concealing the quantity or destination of communication is called traffic confidentiality

n  Even with confidentiality there still remain threats for the website customer.

n  An adversary who can’t read the contents of your encrypted message might still be able to change a few bits in it, resulting in a valid order for, say, a completely different item or perhaps 1000 units of the item.

n  There are techniques to detect, if not prevent, such tampering.

n  A protocol that detects such message tampering provides data integrity.

n  The adversary could alternatively transmit an extra copy of your message in a replay attack.

n  To the website, it would appear as though you had simply ordered another of the same item you ordered the first time.

n  A protocol that detects replays provides originality.

n  Originality would not, however, preclude the adversary intercepting your order, waiting a while, then transmitting it—in effect, delaying your order.

n  The adversary could thereby arrange for the item to arrive on your doorstep while you are away on vacation, when it can be easily snatched. A protocol that detects such delaying tactics is said to provide timeliness.

n  Data integrity, originality, and timeliness are considered aspects of the more general property of integrity.

n  Another threat to the customer is unknowingly being directed to a false website.

n  This can result from a DNS attack, in which false information is entered in a Domain Name Server or the name service cache of the customer’s computer.

n  This leads to translating a correct URL into an incorrect IP address—the address of a false website.

n  A protocol that ensures that you really are talking to whom you think you’re talking is said to provide authentication.

n  Authentication entails integrity since it is meaningless to say that a message came from a certain participant if it is no longer the same message.

n  The owner of the website can be attacked as well. Some websites have been defaced; the files that make up the website content have been remotely accessed and modified without authorization.

n  That is an issue of access control: enforcing the rules regarding who is allowed to do what. Websites have also been subject to Denial of Service (DoS) attacks, during which would-be customers are unable to access the website because it is being overwhelmed by bogus requests.

n  Ensuring a degree of access is called availability.

n  In addition to these issues, the Internet has notably been used as a means for deploying malicious code that exploits vulnerabilities in end-systems.

n  Worms, pieces of self-replicating code that spread over networks, have been known for several decades and continue to cause problems, as do their relatives,  viruses, which are spread by the transmission of “infected” files.

n  Infected machines can then be arranged into botnets which can be used to inflict further harm, such as launching DoS attacks.

So that's it. We are done with problems. Now we will discuss solution and many techniques to counter these problems for you in next post. Stay Tuned.