Hai guys !
Here i put a simple basic quests to u.

if suppose i have an intranet dumped with 30 pcs
each has linux as its os.
At any instant all of my 30 pcs are alive.

1. In such a situation if a user unexpectedely changes its ip to be one which already a system has with that ip and functioning in the intranet,
what will be the consequences of it ?
will both the m/cs able to receive the packets arriving to it or not.

2.In the same situation instead of changing the Ip if the user changes the MAC address of the NIC card which is the same the other machine have then will the second machine recives all the packets arriving to that MAC ip?

3. If the case i assume that both the m/cs receive the packets then how can i get such packets at application layer. what i need to do to get the packets at application layer?

4.If possible can u breif me how the hackings are done in the internet.

Iam expecting suitable answers for my questions guys.

Thankyou guys.

I set two pcs to the same ip. They were connected to the internet by a satallite modem.

They both got errors. About 50% loss.

They did not complain like windows will if this happens, they both worked.

Just a lot of errors.

Setting two IP address to be the same on one network will cause serious errors and possible lack of connectivity. Basically it is like trying to talk to two guys named Bob in a conference call, without any other way to tell them apart... Bob gets the message, but Bob has no idea why you told him, and Bob says that he didn't get it so you tell him again, but Bob says that he already knew that and doesn't know why you told him in the first place... Get the idea?

If am not mistaken the MAC address can NOT be changed it is hard coded into the NIC at the factory (I may be wrong on this one).

In order to recieve data at the application layer you need to have a software package that will listen to a specific IP port on the PC. Essentially you are listening on 192.168.2.15 : 5005. 5005 is the port number you are listening too. If you are looking to get a single message to every PC on a network I believe having the originating software send to the broadcast address (x.x.x.255) should do it. I haven't played around with it that much.

Hacks are essentially getting into someone elses computer. There are many different types of hacks. Far too many to go into on a message board, nor do I really feel like spreading that kind of knowledge. Essentially if you are looking to gain control of a PC you have to gain administrative (root) privledges. If you want to just crash (more widely known as an attack rather than a hack) there are several security holes in IIS and most Windows based software you can exploit. Check M$'s website for "security patches" (Otherwise known as the "hack-me-here page").

-Dizzy