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therefore no longer taken into consideration (but they must always have a name beginning with “S” followed by two characters and the actual name of the script used for the dependencies). Generally, base services (such as logging with rsyslog, or port assignment with portmap) are started first, followed by standard services and the graphical interface (gdm). This dependency-based boot system makes it possible to automate re-numbering, which could be rather tedious if it had to be done manually, and it limits the risks of human error, since scheduling is conducted according to the parameters that are indicated. Another benefit is that services can be started in parallel when they are independent from one another, which can accelerate the boot process. ALTERNATIVE Other boot systems This book describes the boot system used by default in Debian (as implemented by sysvinit package), which is derived and inherited from System V Unix systems, but there are others. In the original System V, and in versions of Debian up to Lenny, the execution order of initialization scripts was defined only by the names of the /etc/rc*. d/S* symbolic links (and /etc/rc*.d/K* upon shutdown). This behavior can be re-established by seing CONCURRENCY=none in the /etc/default/rcS file. file-rc is another boot system with a very simple process. It keeps the principle of runlevels, but replaces the directories and symbolic links with a configuration file, which indicates to init the processes that must be started and their launch order The newly arrived upstart system is still not perfectly tested on Debian. It is event based: init scripts are no longer executed in a sequential order but in response to events such as the completion of another script upon which they are dependent. This system, started by Ubuntu, is present in Debian Squeeze, but is not the default; it comes, in fact, as a replacement for sysvinit, and one of the tasks launched by upstart is to launch the scripts wrien for traditional systems, especially those from the sysv-rc package. Another new option is systemd, but it still lacks the maturity needed to be part of Squeeze. Its approach is opposite to the previous systems; instead of preemptively launching all services, and having to deal with the question of scheduling, systemd chooses to start services on demand, somewhat along the principle of inetd. But this means that the boot system must be able to know how services are made available (it could be through a socket, a filesystem, or others), and thus requires small modifications of those services. There are also other systems and other operating modes, such as runit, minit, or initng, but they are relatively specialized and not widespread. init distinguishes several runlevels, so it can switch from one to another with the telinit new-level command. Immediately, init executes /etc/init.d/rc again with the new runlevel. This script will then start the missing services and stop those that are no longer desired. To do this, it refers to the content of the /etc/rcX.d (where X represents the new runlevel). Scripts starting with “S” (as in “Start”) are services to be started; those starting with “K” (as in “Kill”) are the services to be stopped. The script does not start any service that was already active in the previous runlevel. 186 The Debian Administrator's Handbook
By default, Debian uses four different runlevels: • Level 0 is only used temporarily, while the computer is powering down. As such, it only contains many “K” scripts. • Level 1, also known as single-user mode, corresponds to the system in degraded mode; it includes only basic services, and is intended for maintenance operations where interactions with ordinary users are not desired. • Level 2 is the level for normal operation, which includes networking services, a graphical interface, user logins, etc. • Level 6 is similar to level 0, except that it is used during the shutdown phase that precedes a reboot. Other levels exist, especially 3 to 5. By default they are configured to operate the same way as level 2, but the administrator can modify them (by adding or deleting scripts in the corresponding /etc/rcX.d directories) to adapt them to particular needs. Figure 9.1 Boot sequence of a computer running Linux All the scripts contained in the various /etc/rcX.d directories are really only symbolic links — created upon package installation by the update-rc.d program — pointing to the actual scripts Chapter 9 — Unix Services 187
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The Debian Administrator's Handbook
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3.1.3 Integration with Other Linux/
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6.5 Checking Package Authenticity .
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9.4.1 Administrating On a Web Inter
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11.5 Seing Up Windows Shares with S
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14.2 Firewall or Packet Filtering .
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B.2.2 The User's Home Directory . .
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Foreword Linux has been garnering s
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Book Structure Following the struct
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While we were obviously satisfied w
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Tobias Gruetzmacher, Tournier Simon
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Keywords Objective Means Operation
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1.1. What Is Debian? CULTURE Origin
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TOOL Installer debian-installer is
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COMMUNITY Upstream author, or Debia
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➨ http://www.opensource.org/licen
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1.3.1. The Debian Developers Debian
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with the changelog.gz file (or equi
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were only lile challenges at the be
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can always fine-tune these paramete
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PERSPECTIVE Debian for multimedia A
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Each specific service has its own s
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tool. Whether used in graphical or
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Figure 1.2 Compilation of a package
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their work. The next step is the in
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28 The Debian Administrator's Handb
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Keywords Falcot Corp SMB Strong Gro
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We have envisioned this case study
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Several factors have dictated this
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• A survey of several French serv
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Chapter Analyzing the Existing Setu
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Figure 3.1 Coexistence of Debian wi
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Figure 3.2 Database backups Each se
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HARDWARE Next-generation PC Most re
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Keywords Installation Partitioning
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BACK TO BASICS A catch-up course in
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copy the previously downloaded ISO
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of the two, and GRUB, a more modern
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Figure 4.3 Selecting the country 4.
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4.2.9. Configuring the Clock If the
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(swap) will be stored. This task is
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Figure 4.9 Guided partitioning The
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IN PRACTICE Shrinking a Windows par
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“Create a volume group”, to whi
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Figure 4.12 Selecting a Debian mirr
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accessible from the boot menu. You
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TIP Debian thinks of speakers of no
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Chapter Packaging System: Tools and
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Chapter 7, Solving Problems and Fin
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SHA1: 350a8a7a43fe182d54f3b7d73b803
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5.2.1.2. Conflicts: the Conflicts f
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Figure 5.1 Use of a Provides field
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name. This directory also includes
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postinst and similar scripts. But t
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-----BEGIN PGP SIGNED MESSAGE-----
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and a set of upstream patches contr
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Updating database of manual pages .
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which the file comes; --status pack
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Iceweasel is a redesign of the Mozi
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handles other packaging formats, es
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Chapter Maintenance and Updates: Th
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The syntax of the last field depend
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6.1.1.2. The Backports From backpor
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6.2.1. Initialization For any work
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6.2.3. System Upgrade Regular upgra
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it can be configured through severa
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TIP Comments in /etc/apt/ preferenc
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6.4. Frontends: aptitude, synaptic
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like aptitude has always done. It c
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aptitude's log will only contain a
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“Authentication” tab in the Sei
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compiled by the package maintainers
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Figure 6.3 Upgrading with update-ma
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IN PRACTICE The Falcot Corp case Fa
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purpose is editing. Browsing this c
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Chapter Solving Problems and Findin
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Man pages not only document program
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Page 168 and 169: Keywords Configuration Localization
Page 170 and 171: This chapter reviews everything inc
Page 172 and 173: The questions are relevant to the p
Page 174 and 175: to 1 Gb/s). The most widely used ca
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Page 178 and 179: Network Manager knows how to handle
Page 180 and 181: TIP Bypassing DNS Since application
Page 182 and 183: 8.4.3. Modifying an Existing Accoun
Page 184 and 185: The creation of an account populate
Page 186 and 187: 8.7. Printer Configuration Printer
Page 188 and 189: Configuration of the bootloader mus
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Page 192 and 193: kernel /vmlinuz root=/dev/sda2 init
Page 194 and 195: The timezone, configured during ini
Page 196 and 197: GOING FURTHER GPS modules and other
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Page 200 and 201: 8.10.1. Introduction and Prerequisi
Page 202 and 203: the choices saved in the .config fi
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Page 206: This requires, however, that lilo b
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Page 211: • checking the integrity of files
Page 215 and 216: BACK TO BASICS Client, server A sys
Page 217 and 218: that requires frequent connections
Page 219 and 220: For any connection established on t
Page 221 and 222: When the VNC session is closed, rem
Page 223 and 224: There are two ways of presenting ri
Page 225 and 226: Webmin is used through a web interf
Page 227 and 228: • news: Usenet subsystem message
Page 229 and 230: 9.6. The inetd Super-Server Inetd (
Page 231 and 232: SECURITY Restricting cron or atd Yo
Page 233 and 234: # Restart the IRC proxy after each
Page 235 and 236: update the quotas in the absence of
Page 237 and 238: of backups can be kept in a small a
Page 239 and 240: The Falcot Corp administrators are
Page 241 and 242: • ACTION: the action correspondin
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Page 245 and 246: ATTENTION Graphics card and standby
Page 247 and 248: Chapter Network10 Infrastructure Co
Page 249 and 250: sent through to the masqueraded con
Page 251 and 252: CULTURE SSL and TLS The SSL protoco
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GOING FURTHER Optimal configuration
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# (/proc/sys/net/ipv6/conf/all/acce
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so that a security vulnerability in
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Example 10.12 Excerpt of /etc/bind/
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} option broadcast-address 192.168.
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10.8.2. Remote Diagnosis: nmap nmap
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The packet currently displayed was
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Chapter 11 Network Services: Postfi
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the ISP's SMTP server, which is alw
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alias_database = hash:/etc/aliases
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virtual_mailbox_base = /var/mail/vh
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The last two rules reject any messa
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The reject_unlisted_recipient rule
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failed messages later), especially
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# Unfiltered addresses postmaster@f
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Note that the SASL database was cre
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Apache is a modular server, and man
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# New log format including (virtual
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11.2.3.2. Restricting Access The Al
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➨ http://www.falcot.com/cgi-bin/a
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RPC services register to a director
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option, which disables this behavio
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The package also proposes identifyi
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1 5 Specifies the character set and
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username = user password = password
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11.6.3. Configuring a Filter squid
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objectClass: dcObject objectClass:
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Question Answer LDAP server Uniform
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and so on). The answer to the “co
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go into deeper detail for some conc
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Chapter Advanced12 Administration C
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CULTURE Independent or inexpensive?
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RAID-5 RAID-5 addresses the asymmet
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Filesystem label= OS type: Linux Bl
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there will be a synchronization pha
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[...] Update Time : Thu Sep 30 15:5
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Fortunately, these lines can be gen
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# pvdisplay "/dev/sdb2" is a new ph
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Allocation inherit Read ahead secto
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# cat /etc/fstab [...] /dev/vg_crit
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[...] # df -h /srv/base/ Filesystem
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• The remaining partitions, sda7
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that gets started) is known as dom0
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or Mandriva). Other methods include
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# xm list Name ID Mem VCPUs State T
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known as control groups, by which d
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into a separate switch, with the co
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done. INIT: Entering runlevel: 3 St
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12.2.3.2. Network Configuration Jus
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is accessible from all interfaces;
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We will only give a rough overview
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• from the network; preseeding th
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12.3.3. Simple-CDD: The All-In-One
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12.4. Monitoring Monitoring is a ge
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Finally, when a plugin is invoked w
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According to its type, each object
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check_command } define service{ use
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Keywords Workstation Graphical desk
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13.1. Configuring the X11 Server Th
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oth versions are available in Squee
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contains commented examples. Last,
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Figure 13.2 The KDE desktop Since t
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Evolution is the GNOME email client
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Strictly speaking, Debian Squeeze c
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The next versions of these applicat
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13.4.4.3. Collaborative Work With F
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The Windows partition must first be
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Chapter Security14 Contents Definin
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ut the other elements should also b
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• INPUT: concerns packets whose d
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Other actions, particularly those c
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Figure 14.2 Fwbuilder's main window
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• those that qualify a message as
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14.3.3.1. Auditing Packages: debsum
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The chkrootkit and rkhunter package
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Figure 14.3 Security contexts and U
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The aptitude install selinux-basics
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# semanage login -a -s user_u rhert
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# myapp executable will have: # lab
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GOING FURTHER The m4 macro language
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Message avc:denied { read write } p
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➨ http://en.wikipedia.org/wiki/SQ
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features imply a increased risk of
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confronted with these unfortunate c
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sure of actually fixing it; otherwi
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(...) ** 2004-11-29-19:50:49: DCC S
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Chapter Creating a Debian15 Package
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editor shows us that dch really did
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15.2. Building your First Package 1
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particular case, library, is useful
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The interpretation of such a rule i
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ALTERNATIVE apt-ftparchive If mini-
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a huge problem as soon as the error
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EXTRA Lightweight process for “De
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not yet gone through the new mainta
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Chapter Debian's16 Conclusion: Futu
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16.3. Future of this Book We would
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These objectives necessarily involv
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A.7. Damn Small Linux This distribu
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$ pwd /home/rhertzog $ cd Desktop $
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tmpfs 514208 269136 245072 53% /dev
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B.3.1. The Deepest Layer: the Hardw
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B.4. Some Tasks Handled by the Kern
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B.4.3. Shared Functions Since a num
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comes back when the execution of th
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• the standard C library (glibc),
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alternative, 356 am-utils, 173 aman
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Collins, Ben, 12 command line inter
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edquota, 209 eGroupware, 366 EHLO,
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in-addr.arpa, 241 Includes, Apache
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lspci, 444 lspcmcia, 444 lsusb, 444
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hardware acceleration, 190 openswan
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ead, right, 196 README.Debian, 11,
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suite, office, 368 super-server, 20
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Z Zabbix, 343 Zacchiroli, Stefano,
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