Oooh god

I need few steps, not a CCIE!!!!!

Still young for this :)

that's a high level overview of network security...and it really sounds like that might be what you need - in the long run.

in the short term, we need more information from you to recommend specifics. is your problem on a router or firewall? model? IOS version? OS version? etc. what are you trying to prevent, or what would you like to prevent. we need specifics.

Yes, you're totally right and i'm sorry.

I have 1841 router 12.4 IOS, HWIC-4ESW.

I'm using access lists for all used ports.

And I'm using NAT becuase we are using a regular 3.5G router modem, so we need a NAT.

one of my subnetworks requires to access internet, and single computer in another subnetwork.

The people in that computer's subnetwork figured out that he can access internet, so they change thier IPs.

I tried to prevent changing the IPs by taking the administrative rights from them. But now, they are using another computers, they are using thier personal laptops, they simply plug the network cable that connects thier company's desktop computers.

I'm so angry of this behavier, do you agree with me?

If yes, please help me to prevent it.

I think that I have to do some encryption on router and install the encryption key on the Windows XP or Vista.

But how to do this, this is my question.

Static the IP's that need no blocking and create a restrictive ACL to block everyone else.