Running Mac OS X Tiger

Nonhuman Users

Even if you are the only human user of the system, there are well over a dozen accounts on the system. Most of these user accounts are not intended for use by you or any user on the system but are set up for use by various services and programs on the system. These nonhuman accounts let applications, such as the Apache web server and the Postfix mail server, run in a controlled environment so if they are breached by a hacker, the potential damage is limited. Table 6-1 lists some of the nonhuman users that are defined on the system.

Table 6-1. Some of Mac OS X’s nonhuman users

Username	User ID	Description
root	0	The administrative user
daemon	1	Core system daemons
lp	26	Printing service
postfix	27	The Postfix SMTP server
www	70	The Apache web server
nobody	99	A user with greatly restricted access

Many of the nonhuman users, such as cyrusimap and qtss, aren’t used on the average person’s system but instead are defined for use on Mac OS X Server. Others, such as postfix and www, are used only when you run the Postfix mail server or the Apache web server. Under most conditions, you’ll notice only processes owned by either your own ID or by the root user when viewing processes in the Activity Monitor or with the ps command.

Creating a Nonhuman User

If you need to create a nonhuman user for some reason (for example, to run some server program securely), you shouldn’t create that user account with the Accounts preference panel; ...