Linux system administration — Students’ notes Anton Altaparmakov Darran Bryant David Carter Bob Dowling Ben Harris Julian King Stella Page December 16, 2003 1 2 CONTENTS 3 Contents 0 Introductory remarks 21 0.1 This course . 21 0.2 Linux . 23 1 Installing Red Hat Linux 31 1.1 Concepts . 32 1.2 Before you install . 38 1.3 An installation walk through . 41 2 XFree86 61 2.1 Introduction . 61 2.1.1 Graphics cards . 61 2.1.2 Framebuffers and VESA mode . 61 2.1.3 Some DDC magic . 61 2.1.4 Power Management . 62 2.2 Configuring XFree86 . 62 2.2.1 Device . 67 2.2.2 Mice . 68 2.2.3 Keyboards . 71 2.2.4 Files . 72 2.2.5 Monitor . 73 2.2.6 Screen . 75 2.3 ServerLayout . 77 2.4 Commercial X servers . 78 2.5 Window Managers . 78 4 CONTENTS 2.6 Play time . 80 2.7 External Documentation . 82 2.8 Graphical Logins . 82 3 The Red Hat Software Package System 83 3.1 Software management . 83 3.2 Querying packages . 85 3.3 Installing packages . 91 3.4 Dependencies . 94 3.5 Removing packages . 96 3.6 Overriding dependency checks . 97 3.7 Upgrading packages . 98 3.8 Checking a package . 100 3.9 Postinstall scripts . 103 3.10 Miscellaneous notes . 104 3.11 Building software from source code . 104 4 Boot sequence 109 4.1 Introduction . 109 4.2 BIOS – the Basic Input/Output System . 109 4.3 GNU GRUB – The Grand Unified Bootloader . 111 4.4 Kernel startup . 115 4.5 init . 116 4.6 Changing runlevels . 122 5 Network concepts 125 CONTENTS 5 6 The kernel 149 6.1 /proc: The window on the kernel . 149 6.2 Kernel upgrades . 151 7 Service configuration 155 7.1 Continually running services . 155 7.2 Network services run from xinetd . 158 7.3 Services run from crond . 161 7.4 Log files . 164 7.5 A review of common services . 165 8 Managing users and groups 171 9 Practical filesystems 183 9.1 Introduction . 183 9.2 Hardware . 183 9.3 Filetypes . 184 9.4 What is in a name? . 185 9.5 Partitioning disks . 185 9.6 fdisk . 185 9.7 Things you need to know to use fdisk . 186 9.8 Using fdisk . 186 9.9 Creating a partition . 188 9.10 Filesystems . 189 9.11 Creating a filesystem . 190 9.12 Mounting filesystems . 190 9.13 /etc/fstab . 192 6 CONTENTS 9.14 tunefs . 192 9.15 Backups . 193 9.16 Filesystems concepts . 194 9.16.1 Mode . 195 9.16.2 Timestamps . 195 9.17 fsck . 196 9.18 Advanced Filesystems . 197 10 Security 199 10.1 Defences . 200 10.2 Access controls . 202 10.3 Password security . 205 10.4 Network sniffing . 206 10.5 SSH – the Secure Shell . 207 10.6 X11 security . 210 10.7 Threat models – know your enemy . 212 10.8 Dealing with attacks . 214 11 The Network File System 217 11.1 Introduction . ..