FreeBSD Tutorial

Index

Accounts Information
Creating a User Account for Yourself
Some Basic FreeBSD Commands
Command Line Editing
Using vi as an Editor
Post-installation Configuration
Short Example Using FreeBSD Commands
SSH and SCP instead of Telnet and FTP
Getting FreeBSD 6.3 Files and Others
pkg_add: Adding Packages or Ports by Hand
Network Information
    ifconfig
    rc.conf
    Stopping and Starting the Network
    Stopping and Starting Services
Installation Notes
Slices and Partitions
Distribution Sets
Quick Installation Guide (Using CD-ROM)
The FreeBSD Directory Structure
A Few Differences from Linux
VI tutorial

Introduction

Accounts Information

ACCOUNT:         root
PASSWORD:      Given in class

PLEASE! Do not change the root password. This will cause numerous problems throughout the workshop. The machine in front of you is yours for the duration of the workshop.

IF YOU CHANGE THIS PASSWORD YOUR MACHINE MAY BE REINSTALLED FROM SCRATCH!

Creating a User Account for Yourself

If you already did this during the Sunday introductory FreeBSD session, we still need you to do this again to make sure that everyone has the same configuration. You should have removed your user account at the end of the day on Sunday.

There are several ways to do this. We'll use one method for now, but you can use the interactive adduser script if you wish. This may require additional setup on your part the first time you run the script.

Below create the exim user account and your own personal user account as well using the following commands:

• pw useradd exim -u 90

• pw useradd username -m -G exim,wheel -s /usr/local/bin/bash

The first command created the account exim with no home directory and a UID of 90. The second command created your personal userid that you will use during the rest of this workshop, automatically setup a home directory for the userid ("-m" option), placed the user in the wheel and exim groups, and set the default shell to be bash.

By placing your user in the wheel group this allows you to become the superuser root by using the su command. For more information on the pw command type man pw at the prompt.

Now you need to set the password for your new account so that you can login on that account. To do this type:

• passwd username

Follow the prompts to enter in a new password. Pick something secure...

Some Basic FreeBSD Commands

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Command Line Editing

FreeBSD by default uses sh or csh, which provide very rudimentary editing capabilities. Bash has much better editiing features so you want want it install it for you account's use. We do not recommend changing the default shell of root; rather, use 'su -m' rather than 'su' to get root access using your environment instead of the default root environment. If you want the default root environment use 'su -' instead.

# bash
bash-2.03# 

If you change the default shell for root it is possible to create a situation where you cannot get a a shell if your machine's environment becomes damaged.

Using 'vi' as an Editor

If you are unfamiliar with the 'vi' text editor, here is the absolute minimum set of commands you need to know. Beware: when you start 'vi' it is in command mode, so anything you type is interpreted as a command, not text to be entered! We have included additional commands and a longer vi tutorial as a handout for the workshop.

Post-installation Configuration

There is a menu-based system you can use for configuring the system - setting IP address, configuring hostname, adding further distribution sets and packages, adding users etc: # sysinstall

However, you may find that some of this is quicker to do from the command line, some of which is explained below.

Short Example Using Some FreeBSD Commands

We will be placing source for programs during the workshop in a directory called /usr/local/src. See the Installation Notes section below for more information on partition slices.

To create /usr/local/src do the following:

• cd /usr/local

• mkdir src

Take a look at what's in /usr/local/src (which is nothing):

• ls

• ls -al (long listing and all files - note "." files)

SSH and SCP instead of Telnet and FTP

From now on, use SSH and SCP instead of Telnet and FTP. Telnet and FTP send your passwords and sessions out using clear text - no encryption. This is bad and a major security hole. We will, however, use FTP for anonynmous user sessions to get software. This is because with anonymous ftp your password is your email address. If supported, you can use SFTP as well.

Note: if you are accustomed to using telnet, ssh looks almost identical and will behave the same for much of what you wish to do, but ssh has much more functionality available if you decide to use it.

Basic SSH and SCP Commands

Getting FreeBSD 6 Files and Others

The FreeBSD 6.3 CD-ROM contents have been made available to you locally. Additional files may be placed in /pub (see below) as needed.

• ftp noc.sse.ws.afnog.org

• login as userid anonymous

• username@ws.afnog.org

• cd /pub/FreeBSD/ports/i386/packages-6.3-release/Latest [to get FreeBSD 6.3 packages]

pkg_add: Adding Packages or Ports by Hand

Many third-party software is supplied in ready-to-use form, but is not in the base system. This is (a) to keep the base system smaller, and (b) because of different licensing terms. (The FreeBSD license is actually less restrictive than the GNU/GPL license under which a lot of open-source software is distributed)

All this third-party software installs under /usr/local.

You can use sysinstall to add packages, but it is quicker to use 'pkg_add' from the command line. The example below assumes that you have the FreeBSD mounted to the mount point /cdrom. For example, to add the editor 'emacs':

# cd /cdrom/packages/All
# ls
# pkg_add emacs-21.3_7.tbz

[For the workshop you can simply enter in the command below. Note that you must be root
to do this.]

# pkg_add ftp://noc.ws.afnog.org/pub/FreeBSD/ports/i386/packages-6.3-release/Latest/emacs-21.3_9.tbz
# pkg_add -r emacs    N.B: This help in remote installation of the emacs package

Note that the configuration files for third-party software are in /usr/local/etc, and scripts to start daemons are installed under /usr/local/etc/rc.d, and /etc/rc.d.

You can also compile packages directly from the source code, if you have the "ports" distribution installed. The ports system automatically fetches the source file via FTP or anonCVS, applies any FreeBSD-specific patches, and compiles and installs the code. A "package" is really just a "port" which has been compiled.

Vi /etc/make.conf

add:

PERL_VERSION=5.8.8

MASTER_SITE_OVERRIDE="ftp://noc.sse.ws.afnog.org/pub/distfiles/"

# cd /usr/ports/editors/emacs
# make
# make install
# make clean

Sometimes you will find that a "port" exists, but no corresponding binary "package". This is usually because of licensing or export restrictions. The "port" is always able to be distributed because it does not include any software, only instructions on how to fetch and compile the software from somewhere else.

You can query installed packages, or package .tbz files, using pkg_info.

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Network Information

ifconfig

This is the command you use to interactively start and stop network interfaces and to define how they run. You need root access to use this command.

rc.conf

The main system configuration file is /etc/rc.conf. This file is edited by sysinstall, but it's perfectly OK to edit this by hand. It is in this file that you configure the hostname, IP address for each interface, and so on. Changes you make in here won't take effect until you reboot.

Defaultrouter="196.200.219.254"
hostname="pc1.sse.ws.afnog.org"
ifconfig_em0="inet 196.200.219.1 netmask 255.255.255.0"

# On hosts where you don't want sendmail to accept incoming port 25
# (but you still want daemons to be able to send outgoing mail):
sendmail_flags="-q30m"

The sendmail flag is not set in this workshop. The full list of options, and their default values, can be found in /etc/defaults/rc.conf - but don't edit this file, edit /etc/rc.conf instead. This makes it easier to upgrade your system to a later version of FreeBSD.

Stopping and Starting the Network

You may be used to something like "/etc/rc.d/init.d/network stop" under Linux. Under FreeBSD this functionality resides in /etc/rc.conf and is parsed at system startup. So, to stop your currently running network first use ifconfig to figure out what interface you wish to stop.

• ifconfig

This displays your network interface status. Notice that "em0" (Fast Ethernet) has an IP address assigned. Not that lo0 as an address as well. This is your loopback device. To bring sis0 down type:

• ifconfig em0 down

Now to bring it back up just type:

• ifconfig em0 up

There is quite a bit more to ifconfig and we'll discuss this during the Monday evening FreeBSD session as well, or you can type "man ifconfig" for more information. Review the "rc.conf" section above as well.

Stopping and Starting Services

By default, system services are configured in /etc/rc.conf and are started at system startup. If you need to start and stop one of these services (perhaps you changed the service's configuration file) you should do the following:

• ps -awx

or to find a particular running service, like sendmail, try:

• ps -awx | grep ssh

You'll get output that includes the process ID number on the left. If you make a change to the process's configuration, or just need to restart the process, you can do the following:

• kill -HUP process#

Note, if the service is a third party package, then you can often find configuration files for the service in /usr/local/etc/. In addition you may find shell scripts that can start and stop the service with command line parameters in /usr/local/etc/rc.d. Use these scripts instead, when available, to start and stop a service. Default services are now being placed in /etc/rc.d, so you may need to use one of these scripts to stop/start a service.

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Installation Notes

Slices and Partitions

What MS-DOS calls partitions are called "slices" by FreeBSD. FreeBSD almost always sits in a single slice.

The FreeBSD slice is then divided into "partitions". Example:

/dev/ad0     -- first ATA/ATAPI (IDE) hard drive
/dev/ad0s1   -- first slice (MSDOS "partition") on first IDE hard drive
/dev/ad0s1a  -- first partition in this FreeBSD slice
/dev/ad0s1b  -- second partition in this FreeBSD slice
/dev/ad0s1e  -- third (usable) partition

For historical reasons, partitions c and d are not used. We strongly recommend you configure your partitions as:

a:       root filesystem (/)
b:       swap space
e,f...:  other filesystems

All "large" parts of the filesystem should be separate from the root, so that the root itself remains small (less likely to get corrupted). This means at least /usr and /var, and possibly also /home if you have user accounts. One convention you might consider would be to create a resonable sized /var partition (for variable data like logs), then put all remaining disk space in a partition called /usr, and put home directories under that (/usr/home/username)

Distribution sets

FreeBSD comes in several parts:

• "distribution sets" are the parts of the base system. The "bin" distribution is the minimum you can install. However there are additional distributions such as "manpages" and "XF86336".

• "ports" and "packages" are third-party software, not really part of FreeBSD itself, but supplied alongside it. "ports" build from source code, whilst "packages" are ports which have already been compiled and are ready to install.

Quick Installation Guide (Using CD-ROM & Sysinstall script)

For your reference, here is a sequence of operations you could follow to install a workstation if you had created a sysinstall script to do this. Obviously you should adjust this as required to suit your needs (for example, most servers do not need to have X installed)

Insert boot floppy, change to root floppy when prompted
Skip kernel config
Express install
Delete any existing partitions, then select "Entire disk"
Say Yes to standard partition entry
Select BootMgr

Create partition; ctrl-U to delete number presented, enter "100m" instead
  FS   /
Create partition; ctrl-U; 100m
  Swap
Create partition; ctrl-U; 400m
  FS   /var
Create partition; ctrl-U; 400m
  FS   /usr
Create partition; hit enter to accept number given (i.e. rest of disk)
  FS   /u

X-User  (must hit SPACEBAR, not Enter, to select it)
Yes install ports collection

Default answers to remaining questions (i.e. just hit Enter)
WAIT for install to complete
No extra options after install
Exit install
Reboot (remember to remove floppy and CD)
Login as root
halt

Label machine as being successfully installed.

The FreeBSD Directory Structure

Below is a list of some of the directories used under FreeBSD. This information is taken verbatim from http://www.freebsd.org. For a complete description of the FreeBSD directory structure you can type man hier at the prompt.

The FreeBSD directory hierarchy is fundamental to obtaining an overall understanding of the system. The most important concept to grasp is that of the root directory, ``/''. This directory is the first one mounted at boot time and it contains the base system necessary to prepare the operating system for multi-user operation. The root directory also contains mount points for every other file system that you may want to mount.

A mount point is a directory where additional file systems can be grafted onto the root file system. Standard mount points include /usr, /var, /mnt, and /cdrom. These directories are usually referenced to entries in the file /etc/fstab. /etc/fstab is a table of various file systems and mount points for reference by the system. Most of the file systems in /etc/fstab are mounted automatically at boot time from the script rc(8) unless they contain the noauto option. Consult the fstab(5) manual page for more information on the format of the /etc/fstab file and the options it contains.

A complete description of the filesystem hierarchy is available in hier(7). For now, a brief overview of the most common directories will suffice.

A Few differences from Linux

Other key differences between Linux and FreeBSD center around the naming of devices and some of the configuration files:

Linux:   eth0 = first ethernet device (of any type)
FreeBSD: em0 = first Intel(R) PRO/1000 Network Connection Version, ed0  = first NE2000 device, ep0 = first 3Com 3c509, etc.

Linux:   COM1 serial port = /dev/ttyS0
FreeBSD: COM1 serial port = /dev/cuaa0 (call out) or /dev/ttyd0 (call in)

Linux:   /etc/inittab configures incoming serial connections
FreeBSD: /etc/ttys configures incoming serial connections

The VI Editor

cribbed from:
from www.cs.colorado.edu

To move from insert mode to command mode, use the [ESC] key. If you forget to do this and end up with a ':wq' or something else that you don't want at the end of your line, just backspace over the characters that you don't want, then hit [ESC]. If you hit [ESC] when you are already in command mode, the terminal will beep at you, but it won't do anything to your file. When in doubt, hit [ESC].

To move from command mode to insert mode, use the i, a, o, or O command as described below. There are a few others, but those are the most common.

To use the following commands, you must be in command mode:

Cursor Movement:

A handy thing about these commands is that you can type a number first, and the editor will do the command that many times. For instance, l moves the cursor one character to the right, and 12l moves the cursor twelve characters to the right. You shouldn't see the number or command that you type, by the way. If you do, you are in insert mode; you should backspace over the number and press the [ESC] key, then try again. Note that "^" means "press the control key."

h - moves cursor one character to the left

j - moves cursor one line down

k - moves cursor one line up

l - moves cursor one character to the right

^f - moves cursor one screen forward

^d - moves cursor a half screen down

^b - moves cursor one screen backward

^u - moves cursor a half screen up

^ - moves cursor to the beginning of the line (Shift-6)

$ - moves cursor to the end of a line (Shift-4)

w - moves cursor one word forward, with punctuation and braces as new words

W - moves cursor forward to the next word

b - moves cursor one word backward, with punctuation and braces as new words

B - moves cursor backward to the next word

/pattern - searches for pattern and moves the cursor there

?pattern - searches backwards for pattern and moves the cursor there

Deleting Text:

x - deletes the character the cursor is on

X - deletes the character to the left of the cursor

dd - deletes the entire line the cursor is on

d followed by a cursor movement command deletes that much text. For instance, w moves the cursor forward a word, and dw deletes to the end of the word. The 5h command moves the cursor five characters to the left, and the d5h command deletes five characters to the left.

Inserting Text:

These commands may seem a little confusing at first. The i command means that everything you type until you hit [ESC] will be inserted to the left of the cursor. In other words, this command leaves you in insert mode with the insertion point to the left of where the cursor was when you hit 'i.'

i - inserts text to the left of the cursor (leaves you in insert mode)

a - appends text to the right of the cursor (leaves you in insert mode)

A - appends text at the end of the line (leaves you in insert mode)

o - opens new line under the line the cursor is on (leaves you in insert mode)

O - opens new line above the line the cursor is on (leaves you in insert mode)

How Do I Get Out Of This Thing, Anyway?

When you hit the colon (:), you will see it at the bottom of the screen (unless you are still in insert mode, in which case you should back up over it and press [ESC], then try again). You will see anything you type after the colon at the bottom of the screen. After commands that use a colon, you have to hit the key.

:q! - exits without saving changes

:w - write changes

:wq - write changes, then quit

Line Number Commands

(These are useful for programmers)

^g - shows what line you are on at the bottom of the line

exercises

#1

login as root

pwd

should be in /root

lets create a .forward file...

type vi

i to insert

enter email address you want to forward to root@noc.sse.ws.afnog.org

hit escape to exit from insert mode

enter :wq .forward to write the file out as .forward and exit

#2

lets add a second email address to the .forward file

vi .forward

$ to move to end of line

a to start inserting text to the right of the cursor

hit enter

enter email address root@noc.sse.ws.afnog.org

hit escape

enter:wq to write and quit

#3

lets delete the first entry in the .forward file

vi .forward

enter dd to remove the first line

:wq to write and quit

Remove the .forward file

rm .forward

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Frank Kuse
Liberal borrowing from Brian Candler, and hervey allen and Joel Jaeggli
May 26, 2008