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Issue of January 2003 
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FIREWALLS

Dear Brian
I read your magazine regularly and find it very useful. I want to develop expertise in the area of network security, and I’m specifically interested in Firewalls. Is a Firewall the best security option?

K. Sinthanai Sirpi
Tamil Nadu

Dear K. Sinthanai Sirpi,
Thank you for your letter. I am glad that the magazine has been of interest and utility to you. A Firewall is a system designed to prevent unauthorized access to or from a private network. It can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized users from accessing private networks connected to the Internet. It is considered a first line of defense in protecting private information. For greater security, data can be encrypted. Following are the types of firewalls:

  • Packet filter: Looks at each packet entering or leaving the network and accepts or rejects it based on user-defined rules.
    Application gateway: Applies security mechanisms to specific applications like FTP and Telnet servers. This is very effective, but can impose some performance degradation.
  • Circuit-level gateway: Applies security mechanisms when a TCP or UDP connection is established. Once the connection has been made, packets can flow between the hosts without further checking.
  • Proxy server: Intercepts all messages entering and leaving the network. The proxy server effectively hides the true network addresses.

A Firewall is only a part of a total security solution. A complete solution will typically consist of antivirus programs, Firewalls, intrusion-detection systems, along with management policies.


VSAT for irrigation

Dear Soutiman
I am the Superintendent Engineer at the Irrigation Department of Uttaranchal in Dehradun. We are working on a project called 'Maneri Bhali' and the site is 200 km away from our office. We have offices spread over 13 districts in Uttaranchal and communication between them is a challenge. I saw your article on VSATs on your website and I’m interested in exploring the possibility of installing a VSAT. Can you let me know the various uses of VSAT, details of the hardware necessary for installation and its cost?
Vinay Bhalla
Superintendent Engineer
Irrigation Department, Uttaranchal

Hello Vinay Bhalla
I am glad that the article was of use to you. In a reply to an earlier letter, Joyjit Chatterji at Comsat Max, a VSAT solution provider has suggested the following: It is possible today to provide Internet access anywhere across the country on a VSAT. The solution involves installing, at the client location a VSAT which comprises a 1.2 m antenna and associated electronics. The indoor electronic unit has full routing capabilities and connects to a single PC or LAN. The traffic travelling to and from the client location is carried on a satellite link to our master earth station in New Delhi which has a thick pipe to the Internet through VSNL on fiber. We have multiple gateways and offer guaranteed access of 99.5 percent of the time calculated annually. The advantages of Internet using VSAT are anywhere and anytime availability, high uptime, and consistent performance.

 
     
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