Blocking IP Address

1. How to block a specific IP address.

You should use DHCP service to assign IP addresses to your clients. You can then create a scope (range) of IP addresses that will be distributed to clients. In this scope you can configure exclusion ranges by specifying starting and ending IP address. Addresses from excluded range(s) will not be assigned to clients.

2. How to reserve (assign) an IP address to a specific user or computer.

You cannot assign IP address to a specific user because he/she needs to logon first and to do this must have working TCP/IP stack (if we use TCP/IP).

You can assign IP address to specific computer. Again you will use DHCP service. You must also know physical (MAC) address of your NIC. In DHCP, in your scope, use New Reservation. You will have to specify IP address and MAC address of the adapter to which you want to assign this IP address.

If you're looking for specific TCP/IP configuration per user (e.g. specific IP address) there's software out there that lets you select a specific TCP/IP configuration via menu. Products like J.W. Hance's TCP/IP Switcher and GlobeSoft's TCP/IP Swapper 98 do this sort of thing. You might want to contact these companies to see if they're products will do what you want.

It sounds like you are trying to block a specific user from getting to a specific resource and there are two parts to that: making sure they always have the same IP address and then putting an ACL (access control list) on a router in the path to that destination.

For the first part, you can't attach a specific user to a specific IP or computer name, but you can attach a specific workstation to a specific IP by using a DHCP Name Reservation. Or you could just set that workstation up with a static IP.

The alternative is to use a access control product on the resource to which you want to prohibit access (something like Radius or Tacacs/CiscoSecure).

paul

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