4.2. Virtual Consoles and Terminals

Unless FreeBSD has been configured to automatically start a graphical environment during startup, the system will boot into a command line login prompt, as seen in this example:

FreeBSD/amd64 (pc3.example.org) (ttyv0)

login:

The first line contains some information about the system. The amd64 indicates that the system in this example is running a 64-bit version of FreeBSD. The hostname is pc3.example.org, and ttyv0 indicates that this is the system console. The second line is the login prompt.

Since FreeBSD is a multiuser system, it needs some way to distinguish between different users. This is accomplished by requiring every user to log into the system before gaining access to the programs on the system. Every user has a unique name username and a personal password.

To log into the system console, type the username that was configured during system installation, as described in Section 2.9.6, “Add Users”, and press Enter. Then enter the password associated with the username and press Enter. The password is not echoed for security reasons.

Once the correct password is input, the message of the day (MOTD) will be displayed followed by a command prompt. Depending upon the shell that was selected when the user was created, this prompt will be a #, $, or % character. The prompt indicates that the user is now logged into the FreeBSD system console and ready to try the available commands.

4.2.1. Virtual Consoles

While the system console can be used to interact with the system, a user working from the command line at the keyboard of a FreeBSD system will typically instead log into a virtual console. This is because system messages are configured by default to display on the system console. These messages will appear over the command or file that the user is working on, making it difficult to concentrate on the work at hand.

By default, FreeBSD is configured to provide several virtual consoles for inputting commands. Each virtual console has its own login prompt and shell and it is easy to switch between virtual consoles. This essentially provides the command line equivalent of having several windows open at the same time in a graphical environment.

The key combinations Alt+F1 through Alt+F8 have been reserved by FreeBSD for switching between virtual consoles. Use Alt+F1 to switch to the system console (ttyv0), Alt+F2 to access the first virtual console (ttyv1), Alt+F3 to access the second virtual console (ttyv2), and so on.

When switching from one console to the next, FreeBSD takes manages the screen output. The result is an illusion of having multiple virtual screens and keyboards that can be used to type commands for FreeBSD to run. The programs that are launched in one virtual console do not stop running when the user switches to a different virtual console.

Refer to syscons(4), atkbd(4), vidcontrol(1) and kbdcontrol(1) for a more technical description of the FreeBSD console and its keyboard drivers.

In FreeBSD, the number of available virtual consoles is configured in this section of /etc/ttys:

# name    getty                         type  status comments
#
ttyv0   "/usr/libexec/getty Pc"         cons25  on  secure
# Virtual terminals
ttyv1   "/usr/libexec/getty Pc"         cons25  on  secure
ttyv2   "/usr/libexec/getty Pc"         cons25  on  secure
ttyv3   "/usr/libexec/getty Pc"         cons25  on  secure
ttyv4   "/usr/libexec/getty Pc"         cons25  on  secure
ttyv5   "/usr/libexec/getty Pc"         cons25  on  secure
ttyv6   "/usr/libexec/getty Pc"         cons25  on  secure
ttyv7   "/usr/libexec/getty Pc"         cons25  on  secure
ttyv8   "/usr/X11R6/bin/xdm -nodaemon"  xterm   off secure

To disable a virtual console, put a comment symbol (#) at the beginning of the line representing that virtual console. For example, to reduce the number of available virtual consoles from eight to four, put a # in front of the last four lines representing virtual consoles ttyv5 through ttyv8. Do not comment out the line for the system console ttyv0. Note that the last virtual console (ttyv8) is used to access the graphical environment if Xorg has been installed and configured as described in Chapter 6, The X Window System.

For a detailed description of every column in this file and the available options for the virtual consoles, refer to ttys(5).

4.2.2. Single User Mode

The FreeBSD boot menu provides an option labelled as Boot Single User. If this option is selected, the system will boot into a special mode known as single user mode. This mode is typically used to repair a system that will not boot or to reset the root password when it is not known. While in single user mode, networking and other virtual consoles are not available. However, full root access to the system is available, and by default, the root password is not needed. For these reasons, physical access to the keyboard is needed to boot into this mode and determining who has physical access to the keyboard is something to consider when securing a FreeBSD system.

The settings which control single user mode are found in this section of /etc/ttys:

# name  getty                           type  status  comments
#
# If console is marked "insecure", then init will ask for the root password
# when going to single-user mode.
console none                            unknown  off  secure

By default, the status is set to secure. This assumes that who has physical access to the keyboard is either not important or it is controlled by a physical security policy. If this setting is changed to insecure, the assumption is that the environment itself is insecure because anyone can access the keyboard. When this line is changed to insecure, FreeBSD will prompt for the root password when a user selects to boot into single user mode.

Note:

Be careful when changing this setting to insecure! If the root password is forgotten, booting into single user mode is still possible, but may be difficult for someone who is not familiar with the FreeBSD booting process.

4.2.3. Changing Console Video Modes

The FreeBSD console default video mode may be adjusted to 1024x768, 1280x1024, or any other size supported by the graphics chip and monitor. To use a different video mode load the VESA module:

# kldload vesa

To determine which video modes are supported by the hardware, use vidcontrol(1). To get a list of supported video modes issue the following:

# vidcontrol -i mode

The output of this command lists the video modes that are supported by the hardware. To select a new video mode, specify the mode using vidcontrol(1) as the root user:

# vidcontrol MODE_279

If the new video mode is acceptable, it can be permanently set on boot by adding it to /etc/rc.conf:

allscreens_flags="MODE_279"

All FreeBSD documents are available for download at http://ftp.FreeBSD.org/pub/FreeBSD/doc/

Questions that are not answered by the documentation may be sent to <freebsd-questions@FreeBSD.org>.
Send questions about this document to <freebsd-doc@FreeBSD.org>.