Controlling Socket Connections

When you're dealing with sockets and other network connections, you want to be selective about which hosts you accept connections from. In some cases, you can assume that a firewall or packet-filtering router exists in front of your system (or if you’re running Windows 2000, IP Security—IPSec—filters can help restrict who can connect). Various OSs have different conventions for dealing with this situation. For example, UNIX systems typically run most services through a process named inetd, which accepts incoming connections and refuses any that the configuration file won't allow. Although this approach lets you configure socket-level security in one place, all your applications must work correctly with inetd. Because Windows-based applications typically don't work with an inetd process and because using multiple threads with Windows-based applications is typically more efficient than using multiple processes, the applications you write are on their own when it comes to restricting connections. . . .