IN THIS CHAPTER
Understanding what you (or an attacker) can learn from a network scan
Locating and listing all the devices on a network
Determining which ports are open and responsive on each network device
If you've read the previous few chapters and taken the advice about securing your wired and wireless networks as well as configuring a firewall on each of your Macs, you've made great strides in protecting your computers from network-based threats. But how can you be sure you're safe? How can you test your network to make sure it's as secure from hackers and other external threats as you hope it is?
This chapter contains the answer: You put yourself in the shoes of an attacker who wants to break into your network to run a series of tests to find out just what someone else can learn about your network and, in particular, the Macs connected to it. Once you've identified areas of weakness, you can go back and tweak your hardware and software settings to close security holes.
To perform this analysis, you can undertake a process known as network scanning. This general term refers to any system whereby one can collect data about the hosts on a network by sending a variety of inquiries across the network and analyzing the replies (if any). Of the hundreds of ways one could scan a network, in this chapter, I focus on just a couple of the most common ones —those you can employ without having an extensive understanding of network protocols. However, I want ...