ATul Singh

Isolation Levels in Relational Databases [Feb 2011]  http://highscalability.com/blog/2011/2/10/database-isolation-levels-and-their-effects-on-performance-a.html https://en.wikipedia.org/wiki/Isolation_(database_systems)

Designing a URL Shortening Service like TinyURL Lets design a URL Shortening service like TinyURL. This service will provide short short URLs for a large URL. What is the Problem ? URLs can be pretty huge depending upon the resources like the following : https://news.google.com/topics/CAAqIggKIhxDQkFTRHdvSkwyMHZNREZqY0hsNUVnSmxiaWdBUAE?hl=en-IN&gl=IN&ceid=IN%3Aen  ,  I think this Shortening was majorly used in Twittor where there is a limit of 140 characters.  Requirements of the System Its always necessary to clear out the requirements with the Stakeholders on what are the expectations they are making, This will ensure that our System is designed as per the Requirements.  Questions which are already answered  We need to design a system which will store a shorter version of URL that was given. When somebody clicks that shorter URL , request will hit our Service and they will be redirected to the original URL. Questions wh...

Surrounded by Idiots Do you sometimes feel like you’re surrounded by idiots who just don’t understand anything you say? Odds are that they’re not actually idiots, but their personality types are just different than yours. Know the types of people around you As far back as the fifth century BC, the Greek physician Hippocrates identified four main personality types, which author Thomas Erikson denotes with specific colors. The Red, or Dominant, personality is characterized by ambition, dominance, decisiveness, competitiveness, and an often hot temper. The Yellow, or Inspiring, personality is optimistic, cheerful, and confident. When the game seems lost to everyone else, Yellows will continue finding opportunities. The third personality type is Green, or Stable, denoted by a calm, balanced, easygoing, tolerant, and friendly nature. Greens are great team players, because the last thing they want is to cause a fuss or conflict of any kind. Finally, there’s the Blue, or ...

Although TCP appears to be safe protocol because of all the negotiation involved in session establishment and all the protocol and the precision involved in data exchanged, don't get complacent.its not much secure than it should be. Network Sniffers can be setup  on the unsuspected machine to sniff the data on the network and they can snoop clear text data such userIds and passwords that are not encrypted in any way. I have one of my friend who did all this ,, he sniffed a dozen passwords and played with their network data. He was very much expert in doing sniffing and using them, othes friend don't even know their passwords are just floating in raw txt on the network. Session hijacking software, such as Hunt, uses another approach to exploit an existing TCP session. These attempt to intercept an established TCP session and hijack one end of the connection from the session to an evil host.  The problem is that conventional TCP exchanges do not require an...

An ACK scan operates by sending a TCP ACK frame to a remote port. If there are no responses or an ICMP destination unreachable message is returned, then the port is considered to be "filtered" Scans of ports are done for a variety of reasons, but they usually are used to discover whether a host or hosts are offering a particular service. If a host is found to be offering a service that might be exploitable, the hacker might try to break in using some vulnerability.Often, scans are blatant; the hacker makes no attempt to hide his reconnaissance of your network, except that the computer from which the scans originate might be compromised. The hacker assumes that either no one is monitoring the scanning activity or that by using the compromised host, no one can identify the hacker with the scan. Most likely there will be no attribution because no one can associate the hacker with the scan. This can be done by issuing folowing command #nmap -sA <host_address> Followin...

A " Denial of Service" (DoS) attack is one where the attacker tries to make some resource too busy to answer legitimate requests, or to deny legitimate users access to your machine. Denial of service attacks have increased greatly in recent years. Some of the more popular and recent ones are listed below. Note that new ones show up all the time, so this is just a few examples. Read the Linux security lists and the bugtraq list and archives for more current information. SYN Flooding  - SYN flooding is a network denial of service attack. It takes advantage of a "loophole" in the way TCP connections are created. The newer Linux kernels (2.0.30 and up) have several configurable options to prevent SYN flood attacks from denying people access to your machine or services. Pentium "F00F" Bug  - It was recently discovered that a series of assembly codes sent to a genuine Intel Pentium processor would reboot the machine. This affects every machine with a Pe...