Mac OS X Leopard - ARCAism

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CHAPTER 20 LEOPARD NETWORKING
Finger
In the halcyon days of yore, when Spam was just a delicious luncheon meat and the Internet was
just a military research project, a computer scientist named Les Earnest wrote a program that
would take an e-mail address and “point out” who it belonged to by giving you the person’s
name, whether they were logged on, and where their home directory was.
When the Internet opened for general use, people soon found less earnest uses for Finger,
and the protocol was eventually abandoned. The tool still exists, but mainly as way to generate
the words Connection refused.
Port Scan
You should probably be noticing a theme with Internet tools. That is, they can be used for good
or evil. Of all the tools in Network Utility, nothing fits this profile like Port Scan.
In a nutshell, Port Scan tries every port on a given machine and reports back which ones are
open. This is handy information for potential attackers, which makes it handy information for
potential victims.
It’s also useful for figuring out, say, why a particular Internet service is not working, as having
its port closed will render any Internet application silent.
Advanced Networking with Darwin
As discussed in Chapters 18 and 19, the underlying BSD system, accessible from the Terminal
application, is the place to go for advanced hacking. Many networking utilities have more
options than are available from within Network Utility.
There are also esoteric, specialized, and third-party tools that don’t have graphical versions
and, as such, can only be run in Terminal. Even simple utilities like Ping are at your disposal, as
shown in Figure 20-7.
Figure 20-7. Running network tools from the command line in Terminal