System Configuration in /etc

GNU/Linux Desktop Survival Guide
by Graham Williams

System Configuration in /etc

/etc/debian_version

Contains the debian version.

/etc/exports

This file contains information to tell NFS (Network File Systems) which partitions are to be shared with other systems.

/etc/fstab

This file lists filesystems, possibly spread over multiple drives, partitions, and remote hosts, that can be mounted. At boot time, partitions identifed as auto mount will be auto mounted. Other convenient mount rules for CD-ROMS, DVDs, Floppy drives, etc., are usually also included.

/etc/hosts.allow

This file, and its companion /etc/hosts.deny control access to your computer. The file /etc/hosts.allow lists hosts that are allowed to access the system. If empty then no restrictions apply. Similarly, /etc/hosts.deny is a list of hosts that are not allowed to access the system.

/etc/inetd.conf

This file is the internet server configuration database and is used to identify services like ftp and ssh which should be started. As a security measure it is advisable to comment services which you do not use.

/etc/inittab

This file specifies the processes that are started at bootup and at different runlevels.

/etc/motd

This file (message of the day) is displayed when a user logs on.

/etc/passwd

This file contains user information including login name, password, default shell, and home directory. Because this file is readable (and needs to be readable) by everyone on the system, the password field usually contains an x indicating that the encrypted password is actually located in /etc/shadow, which is only readable by the root user. See Section 70.1 for details of sharing this information across multiple hosts.

/etc/profile

This file contains common user configurations for interactive shells, such as global environment variables.

/etc/services

This file contains a list of network services and identifies which port a service mentioned in /etc/inetd.conf will use.

/etc/securetty

This file lists the terminals (ttys) on which root is allowed to login.

/etc/shells

This file contains the pathnames of all shells installed in the system. A user is allowed to select one of these shells as their default login shell.