Restrict XYZ user access to authorized machines?

How can i Restrict XYZ user access to authorized machines?Please any suggestions.

Thanks

Logon Trigger.
If the user comes from an unauthorized machine you just kick it out.

or block their IP address if theirs is static

Support PAVB. Just to add, you can do it in several ways. I believe you can make the listener filter the connections, or use connection manager.
PAVB's proposal however seems to be simple, easy and reliable.