It can pose a potential security problem, as it reveals so much information about the network. Nslookup gives you the address for an IP number. We use this most often to check on security breaches. If we see a connected number in our logs that is not in any of our IP address ranges, or that doesn t belong to any of the local ISPs that are providing dial-up, we check to see if perhaps someone is dialing in who should not be. Sometimes it helps us identify the original source of a Web site that uses a virtual name.
Finger is a holdover from the original days of the Internet.
Researchers used it to display a text file that described their current project. It also displays when the user last logged in great information for hackers. If someone has not logged in for a long time, then the chances are good that the user will not notice the account being used. This is handy to show the user name or the user logged in, but it is a serious security problem. There have been some safe finger programs developed, if you find that it is an absolutely necessary tool.