Firewalls – Introduction

Firewalls

The Internet has made large amount of information available to the average computer user at home, in business and education. By connecting a private network to the Internet can expose critical or confidential data to malicious attack from anywhere in the world. The intruders could gain access to your sites private information or interfere with your use of your own systems. Therefore, security of network is the main criteria here and firewalls provide this security. The Internet firewalls keep the flames of Internet hell out of your network or, to keep the members of your LAN pure by denying them access the all the evil Internet temptations.

Firewalls can be constructed in quite a variety of ways. The most sophisticated arrangement involves a number of separate machines and is known as a perimeter network. Two machines act as “filters” called chokes to allow only certain types of network traffic to pass, and between these chokes reside network servers such as a mail gateway or a World Wide Web proxy server. This configuration can be very safe and easily allows quite a great range of control over who can connect both from the inside to the outside, and from the outside to the inside. This sort of configuration might be used by large organizations.

NEED OF FIREWALLS:

The general reasoning behind firewall usage is that without a firewall, a subnet’s systems expose themselves to inherently insecure services such as NFS or NIS and to probes and attacks from hosts elsewhere on the network. In a firewall-less environment, network security relies totally on host security and all hosts must, in a sense, cooperate to achieve a uniformly high level of security. The larger the subnet, the less manageable it is to maintain all hosts at the same level of security. As mistakes and lapses in security become more common, break-ins occur not as the result of complex attacks, but because of simple errors in configuration and inadequate passwords.

A firewall approach provides numerous advantages to sites by helping to increase overall host security.

The following sections summarize the primary benefits of using a firewall.

• Protection from Vulnerable Services

• Controlled Access to Site Systems

• Concentrated Security

• Enhanced Privacy

• Logging and Statistics on Network Use, Misuse

• Policy Enforcement

How VPN Works

Why it is required:

1. As a business grows, it might expand to multiple shops or offices across the country and around the world.

2. To keep things running efficiently, the people working in those locations need a fast, secure and reliable way to share information across computer networks.

3. In addition, travelling employees like salespeople need an equally secure and reliable way to connect to their business’s computer network from remote locations.

VPN (virtual private network) – A VPN is a private network that uses a public network (usually the Internet) to connect remote sites or users together. The VPN uses “virtual” connections routed through the Internet from the business’s private network to the remote site or employee. By using a VPN, businesses ensure security — anyone intercepting the encrypted data can’t read it.

Similar other old technologies are:

1. The most common way to connect computers between multiple offices was by using a leased line. Leased lines, such as ISDN (integrated services digital network, 128 Kbps), are private network connections that a telecommunications company could lease to its customers. Leased lines provided a company with a way to expand its private network beyond its immediate geographic area. These connections form a single wide-area network (WAN) for the business. Though leased lines are reliable and secure, the leases are expensive, with costs rising as the distance between offices increases.

 

Today, the Internet is more accessible than ever before, and Internet service providers (ISPs) continue to develop faster and more reliable services at lower costs than leased lines. To take advantage of this, most businesses have replaced leased lines with new technologies that use Internet connections without sacrificing performance and security. Businesses started by establishing intranets, which are private internal networks designed for use only by company employees. Intranets enabled distant colleagues to work together through technologies such as desktop sharing. By adding a VPN, a business can extend all its intranet’s resources to employees working from remote offices or their homes.

Analogy: Each LAN is an Island

Imagine that you live on an island in a huge ocean. There are thousands of other islands all around you, some very close and others farther away. The common means of travel between islands is via ferry. Traveling on the ferry means that you have almost no privacy: Other people can see everything you do.

Let’s say that each island represents a private local area network (LAN) and the ocean is the Internet. Traveling by ferry is like connecting to a Web server or other device through the Internet. You have no control over the wires and routers that make up the Internet, just like you have no control over the other people on the ferry. This leaves you susceptible to security issues if you’re trying to connect two private networks using a public resource.

Continuing with our analogy, your island decides to build a bridge to another island so that people have an easier, more secure and direct way to travel between the two islands.

It is expensive to build and maintain the bridge, even if the islands are close together. However, the need for a reliable, secure path is so great that you do it anyway. Your island would like to connect to yet another island that is much farther away, but decides that the costs are simply too much to bear.

This scenario represents having a leased line. The bridges (leased lines) are separate from the ocean (Internet), yet are able to connect the islands (LANs). Companies who choose this option do so because of the need for security and reliability in connecting their remote offices. However, if the offices are very far apart, the cost can be prohibitively high — just like trying to build a bridge that spans a great distance.

So how does a VPN fit in? Using our analogy, suppose each inhabitant on your island has a small submarine. Let’s assume that each submarine has these amazing properties:

• It’s fast.

• It’s easy to take with you wherever you go.

• It’s able to completely hide you from any other boats or submarines.

• It’s dependable.

• It costs little to add additional submarines to your fleet once you’ve purchased the first one.

  • Although they’re traveling in the ocean along with other traffic, the people could travel between islands whenever they wanted to with privacy and security. That’s essentially how a VPN works. Each remote member of your network can communicate in a secure and reliable manner using the Internet as the medium to connect to the private LAN. A VPN can grow to accommodate more users and different locations much more easily than a leased line. In fact, scalability is a major advantage that VPNs have over leased lines. Moreover, the distance doesn’t matter, because VPNs can easily connect multiple geographic locations worldwide.

• VPN technology is based on the idea of tunneling that involves establishing and maintaining logical network connection.

  With this connection, packets constructed in a specific VPN protocol format are encapsulated within some other base or carrier protocol, then transmitted between a VPN client and server, and finally de-encapsulated on the receiving side.

  VPN – an intro

Authentication Service Security

Modern computer systems provide service to multiple users and require the ability to accurately identify the user making a request.

Password based authentication is not suitable for use on computer network – as it can be easily intercepted by the eavesdropper to impersonate the user.

There are 2 components of security in mobile computing:

1.  Security of Devices : – A secure network access involves mutual authentication between the device and the base station or web servers. So that authenticated devices can be connected to the network to get requested services. In this regard Authentication Service Security is important due to typical attacks on mobile devices through WAN:
   1. DoS attacks: –
   2. Traffic analysis:-
   3. Eavesdropping:-
   4.  Man-in-the-middle attacks: –
2.  Security in network: – Security measures in this regard come from
   1. Wireless Application Protocol (WAP)
   2. use of Virtual Private Networks (VPN)
   3. MAC address filtering