i was wondering if someone could help me with the following problem..

1, my internet center uses a cable connection.now i have a question. a cable connection and an ISDN connection ,are the two the same thing? could you tell me the differnce.i do know that my internet center is permanently hooked on to the net..and so it should have a permanent ip address.there are around ten machines all using windowsNT 4.0 . the setup over there is very secure.ordinary users have only the d: drive to access.we dont have direct access to the software we need. all are made available as shortcuts into the D: drive.the command prompt
is also not available.i cant telnet outside from the machines there. further if i install an exe in the drive it is erased as soon as i log off. however i did manage to temporarily run a few software from which i found out the ip address of all the machines there.the machine i used had an address so i assumed that the server to which i am connected has an ip of ..now the following are my assumptions about the
internet center where i go which i would like you to correct for me if i am wrong...(note that i have only a little knowledge of
i will call the above center CENTER1
naturally all the machines in the CENTER1 will be connected to a server,whose ip address i assumed from above is,which will be configured as a proxy server.i went to another internet center(i will call it CENTER2) that had a command prompt(the dos prompt) on its machine. then i tried to ping the server at CENTER1.i did this because the server at CENTER1 is permanently hooked to the net.i assumed from my experiments that it had an ip of however i got a message "no route to host" and in another center i got the message "host not found".when the results were as above i felt that the ip address is used locally and that the permanent address to connect to the net is configured in the proxy server in different manner compared to ordinary ip configuration.are my assumptions right so far?if so how do i get that ip address
with which the machine is connected to the net?how could i get
access to the machine from outside.i dont intent to harm anyone
or put anyone at unease.the very fact that the owner has made
the setup secure makes me feel like trying to hack in..i believe
the everyone here shares the same enthusiasm.that was why i posed this question here..so how can i gain access(especially privileged) to the machines at CENTER1 from both inside and outside the CENTER1.

2, for the above purposes what tools should i use?how far will port scanning be effective here?in unix i can atleast attempt to connect to remote machines using telnet ftp rlogin etc...
when i attack a remote NT machine what all connections can i attempt? how do i go about gaining access to a remote NT machine??forget options like the machine is running a faulty IIS or things like that.the machine is a proxy server.and thats it..it has no firewall.how do i attack it from outside.i dont expect to get spoon fed.i have read about port scanning, IIS attacks etc.but i have never got a concrete guideline about how to launch an attack,especially on a machine that does not run any services but only acts as a proxy for the internal machines.

i have posted a rather very big question and i hope that i have not wasted your time..once again i mean no harm to anyone.
well the truth is that i do want to hack into the machines at CENTER1.
but only for the thrill.and not cause inconvenience.

thank you very much for your time..
with regards and gratitude for all help rendered so far