Managing Linux ® Systems with Webmin ™ PRENTICE HALL P ROFESSIONAL TECHNICAL REFERENCE UPPER SADDLE RIVER, NJ 07458 WWW.PHPTR.COM Managing Linux ® Systems with Webmin ™ System Administration and Module Development Jamie Cameron Library of Congress Cataloging-in-Publication Data Cameron, Jamie. Managing Linux systems with Webmin / Jamie Cameron. p. cm. ISBN 0-13-140882-8 1. Linux. 2. Operating systems (Computers). I. Title. QA76.76.O63 C3545 2003 005.4’32—dc22 2003016330 Editorial and production services: TIPS Technical Publishing, Inc. Cover design director: Jerry Votta Cover design: Nina Scuderi Manufacturing buyer: Maura Zaldivar Executive Editor: Jill Harry Editorial assistant: Brenda Mulligan Marketing manager: Dan DePasquale © 2004 by Jamie Cameron Published by Pearson Education, Inc. 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Contents at a Glance IINTRODUCTION 1 Introduction to Webmin 1 2 Installing Webmin 6 3 Securing Your Webmin Server 14 II S YSTEM MODULES 4 Users and Groups 19 5 Disk and Network Filesystems 39 6 NFS File Sharing 53 7 Disk Quotas 60 8 Partitions, RAID, and LVM 68 9 Bootup and Shutdown 84 10 Scheduled Commands 93 11 Process Management 99 12 Software Packages 105 13 System Logs 113 14 Filesystem Backups 121 15 Internet Services 129 16 Network Configuration 144 17 Network Information Service 154 18 PPP Server Configuration 165 19 Firewall Configuration 173 20 Setting the Date and Time 191 21 Boot Loader Configuration 195 22 Printer Administration 205 23 Voicemail Server Configuration 215 24 Remote Shell Login 220 25 Running Custom Commands 224 26 Webmin’s File Manager 232 27 Perl Modules 244 28 Status Monitoring with Webmin 250 III S ERVER MODULES 29 Apache Web Server Configuration 264 30 DNS Server Configuration 315 31 CVS Server Configuration 354 32 DHCP Server Configuration 361 33 Downloading Email with Fetchmail 378 34 Managing Majordomo Mailing Lists 388 35 The MySQL Database 405 36 The PostgreSQL Database 428 37 Configuring Sendmail 448 38 Configuring Qmail 476 39 Analyzing Log Files 491 40 The ProFTPD Server 500 41 The WU-FTPD Server 525 42 SSH Server Configuration 544 43 Windows File Sharing with Samba 554 44 Configuring the Squid Proxy Server 577 45 Filtering Email with Procmail 605 46 Creating SSL Tunnels 615 47 Usermin Configuration 620 IV C LUSTER MODULES 48 Cluster Software Management 643 49 Cluster User Management 649 50 Cluster Webmin Configuration 660 VW EBMIN MODULES 51 Webmin Configuration 669 52 Webmin Access Control 688 53 Webmin Servers 700 54 Logging in Webmin 707 VI D EVELOPER’S GUIDE 55 Webmin Module Development 710 56 Advanced Module Development 721 57 Inside the Scheduled Cron Jobs Module 734 58 Creating Webmin Themes 741 59 Inside the MSC Theme 747 60 The Webmin API 751 Contents IINTRODUCTION 1 Introduction to Webmin 1 What is Webmin? 1 Who Should Use Webmin? 2 How and Why Was it Developed? 3 What is this Book About? 4 Who Should Read this Book? 4 Conventions Used in this Book 5 Acknowledgments 5 2 Installing Webmin 6 Downloading Webmin for Your System 6 Installing the RPM Package 7 Installing the tar.gz Package 8 Installing the Solaris Package 10 The Webmin User Interface 10 Uninstalling Webmin 13 Summary 13 3 Securing Your Webmin Server 14 Network Security 14 SSL Encryption 15 Requesting a Valid SSL Certificate 17 Summary 18 II SYSTEM MODULES 4 Users and Groups 19 Introduction to UNIX Users and Groups 19 The Users and Groups Module 20 Creating a New User 21 Editing an Existing User 23 Deleting a User 24 Creating a New Group 25 Editing an Existing Group 26 Deleting a Group 27 Viewing Recent and Current Logins 27 Reading Users’ Email 28 Creating Users from Batch Files 28 Configuring the Users and Groups Module 30 Before and After Commands 34 Module Access Control 34 Other Operating Systems 37 Summary 38 5 Disk and Network Filesystems 39 Introduction to Filesystems 39 The Disk and Network Filesystems Module 40 Mounting an NFS Network Filesystem 40 Mounting an SMBFS Windows Networking Filesystem 43 Mounting a Local ext2 or ext3 Hard Disk Filesystem 44 Mounting a Local Windows Hard Disk Filesystem 45 Adding Virtual Memory 46 Automounter Filesystems 47 Editing or Removing an Existing Filesystem 48 Listing Users of a Filesystem 48 Module Access Control 49 Configuring the Disk and Network Filesystems Module 50 A Comparison of Filesystem Types 50 Other Operating Systems 51 Summary 52 6 NFS File Sharing 53 Introduction to File Sharing with NFS 53 The NFS Exports Module 54 Exporting a Directory 54 Editing or Deleting an NFS Export 55 NFS on Solaris 56 NFS on BSD, MacOS X and OpenServer 57 NFS on Irix 59 Summary 59 7 Disk Quotas 60 Introduction to Disk Quotas 60 The Disk Quotas Module 61 Enabling Quotas for a Filesystem 62 Disabling Quotas for a Filesystem 62 viii Contents Setting Quotas for a User or Group 63 Copying Quotas to Multiple Users 63 Setting Grace Times 64 Setting Default Quotas for New Users 65 Other Operating Systems 66 Configuring the Disk Quotas Module 66 Module Access Control 66 Summary 67 8 Partitions, RAID, and LVM 68 Introduction to Hard Disk Partitions 68 The Partitions on Local Disks Module 69 Adding and Formatting a New Partition 70 Creating a New Filesystem 70 Partition Labels 71 Deleting or Changing a Partition 72 Module Access Control 73 Other Operating Systems 74 Introduction to RAID 74 The Linux RAID Module 75 Introduction to LVM 77 The Logical Volume Management Module 78 Creating a New Volume Group 79 Adding and Removing a Physical Volume 80 Creating and Deleting a Logical Volume 80 Resizing a Logical Volume 81 Creating a Snapshot 82 Summary 83 9 Bootup and Shutdown 84 Introduction to the Linux Boot Process 84 The Bootup and Shutdown Module 85 Configuring an Action to Start at Bootup 85 Starting and Stopping Actions 86 Adding a New Action 87 Rebooting or Shutting Down Your System 89 Configuring the Bootup and Shutdown Module 89 Other Operating Systems 89 The SysV Init Configuration Module 91 Summary 92 10 Scheduled Commands 93 Introduction to Cron Jobs 93 The Scheduled Cron Jobs Module 93 Creating a New Cron Job 94 Editing a Cron Job 95 Controlling Users’ Access to Cron 96 Module Access Control Options 96 Configuring the Scheduled Cron Jobs Module 96 Other Operating Systems 97 The Scheduled Commands Module 97 Creating a New Scheduled Command 98 Summary 98 11 Process Management 99 Introduction to Processes 99 The Running Processes Module 99 Viewing, Killing, or Reprioritizing a Process 101 Searching for Processes 102 Running a Process 103 Module Access Control Options 103 Other Operating Systems 104 Summary 104 12 Software Packages 105 Introduction to Packages 105 The Software Packages Module 107 Installing a New Package 107 Finding and Removing a Package 109 Updating on Debian Linux 110 Updating on Red Hat Linux 111 Other Operating Systems 111 Summary 112 13 System Logs 113 Introduction to Logging 113 The System Logs Module 115 Adding a New Log File 115 Editing or Deleting a Log File 117 Module Access Control 118 Other Operating Systems 119 Summary 120 Contents ix 14 Filesystem Backups 121 Introduction to Backups with Dump 121 The Filesystem Backup Module 121 Adding a New Backup 122 Making a Backup 124 Editing or Deleting a Backup 125 Restoring a Backup 125 Configuring the Filesystem Backup Module 126 Other Operating Systems 128 Summary 128 15 Internet Services 129 Introduction to Internet Services 129 The Internet Services and Protocols Module 130 Enabling an Internet Service 133 Creating Your Own Internet Service 133 Creating and Editing RPC Programs 135 Configuring the Internet Services and Protocols Module 136 Other Operating Systems 138 The Extended Internet Services Module 139 Enabling or Editing an Extended Internet Service 140 Creating an Extended Internet Service 141 Editing Default Options 142 Summary 143 16 Network Configuration 144 Introduction to Linux Networking 144 Viewing and Editing Network Interfaces 146 Adding a Network Interface 147 Configuring Routing 149 Changing the Hostname or DNS Client Settings 150 Editing Host Addresses 151 Module Access Control 152 Other Operating Systems 153 Summary 153 17 Network Information Service 154 Introduction to NIS 154 Becoming an NIS Client 155 Setting Up an NIS Master Server 157 Editing NIS Tables 159 Securing Your NIS Server 160 Setting Up an NIS Slave Server 163 Configuring the NIS Client and Server Module 163 NIS on Solaris 163 Summary 164 18 PPP Server Configuration 165 Introduction to PPP on Linux 165 Configuring a PPP Server 166 Managing PPP Accounts 169 Restricting Access by Caller ID 171 Module Access Control 172 Summary 172 19 Firewall Configuration 173 Introduction to Firewalling with IPtables 173 The Linux Firewall Module 175 Allowing and Denying Network Traffic 177 Changing a Chain’s Default Action 181 Editing Firewall Rules 182 Creating Your Own Chain 182 Setting Up Network Address Translation 183 Setting Up a Transparent Proxy 184 Setting Up Port Forwarding 185 Firewall Rule Conditions 186 Configuring the Linux Firewall Module 189 Summary 189 20 Setting the Date and Time 191 The System Time Module 191 Changing the System Time 192 Change the Hardware Time 192 Synchronizing Times with Another Server 193 Module Access Control 193 Other Operating Systems 193 Summary 194 x Contents 21 Boot Loader Configuration 195 Introduction to Boot Loaders 195 The Linux Bootup Configuration Module 196 Booting a New Kernel with LILO 197 Booting Another Operating System with LILO 198 Editing Global LILO Options 199 The GRUB Boot Loader Module 200 Booting a New Linux Kernel or BSD with GRUB 201 Booting Another Operating System with GRUB 202 Editing Global GRUB Options 202 Installing GRUB 203 Configuring the GRUB Boot Loader Module 203 Summary 203 22 Printer Administration 205 Introduction to Printing on Linux 205 The Printer Administration Module 206 Adding a New Printer 206 Editing an Existing Printer 209 Managing Print Jobs 210 Configuring the Printer Administration Module 211 Module Access Control 212 Other Operating Systems 213 Summary 214 23 Voicemail Server Configuration 215 The Voicemail Server Module 215 Configuring Your System as an Answering Machine 216 Listening to Recorded Messages 218 Setting a Greeting Message 219 Summary 219 24 Remote Shell Login 220 The SSH/Telnet Login Module 220 Configuring the SSH/Telnet Login Module 220 The Command Shell Module 222 The Shell In A Box Module 223 Summary 223 25 Running Custom Commands 224 The Custom Commands Module 224 Creating a New Command 225 Parameter Types 227 Creating a New File Editor 229 Module Access Control 230 Configuring the Custom Commands Module 231 Summary 231 26 Webmin’s File Manager 232 The File Manager Module 232 Navigating Directories and Viewing Files 232 Manipulating Files 234 Creating and Editing Files 234 Editing File Permissions 235 Creating Links and Directories 236 Finding Files 237 Editing EXT File Attributes 237 Editing XFS File Attributes 238 Editing File ACLs 239 Sharing Directories 240 Module Access Control 242 Summary 243 27 Perl Modules 244 Introduction to Perl Modules 244 Perl Modules in Webmin 245 Installing a Perl Module 245 Viewing and Removing a Perl Module 247 Configuring the Perl Modules Module 248 Summary 248 28 Status Monitoring with Webmin 250 The System and Server Status Module 250 Adding a New Monitor 252 Monitor Types 253 Setting Up Scheduled Monitoring 260 Module Access Control 262 Configuring the System and Server Status Module 262 Summary 263 [...]... LDAP server, this module is not for you 19 SYSTEM MODULES T his chapter is devoted to the Users and Groups module, which allows you to create and manage UNIX user accounts and UNIX groups PART II C 20 Chapter 4 • Users and Groups 4.2 The Users and Groups Module The Webmin module Users and Groups that is found under the System category (as shown in Figure 4.1) can be used to create, edit, and delete all... lots more operating systems, and offered many other features The Linux distribution companies Caldera and MSC .Linux have supported the project financially, and many users have made contributions of code patches, modules, translations, and suggestions In addition to the standard modules, over 100 have been written by other people and are available to be added to Webmin on your system once you have installed... Creating, editing, and deleting UNIX login accounts on your system Exporting files and directories to other systems with the NFS protocol Setting up disk quotas to control how much space users can take up with their files Installing, viewing, and removing software packages in RPM and other formats Changing your system' s IP address, DNS settings, and routing configuration Setting up a firewall to protect... Server Module 363 Adding and Editing Subnets 365 Viewing and Deleting Leases 369 Editing Global Client Options 370 Adding and Editing Fixed Hosts 370 Adding and Editing Shared Networks 372 Adding and Editing Groups 373 Module Access Control 374 Configuring the DHCP Server Module 375 Summary 377 33 Downloading Email with Fetchmail 378 Introduction to Fetchmail 378 The Fetchmail Mail Retrieval Module. .. almost all of its modules, and how to write your own The book focuses on the standard modules that come with the Webmin package, not those written by other people Not all of the 83 standard modules are covered, however, as some are not very useful to the average administrator Although this book is written primarily for Linux users, the program behaves almost identically on other operating systems Each chapter... security H A P T E R 4 Users and Groups 4.1 Introduction to UNIX Users and Groups On Linux and other UNIX operating systems, a user is a person who can login to the system via SSH, telnet, FTP or at the console Users can also receive email and own files on the server's local filesystems Each user has a login name, a password, and a home directory in which all its files are stored Users also have several... Types 412 Viewing and Editing Table Contents 412 Deleting Tables and Databases 416 Executing SQL Commands 417 Backing Up and Restoring a Database 417 Managing MySQL Users 419 Managing Database, Host, Table, and Field Permissions 421 Module Access Control 423 Configuring the MySQL Database Server Module 424 Summary 427 428 Introduction to PostgreSQL 428 The PostgreSQL Database Server Module 429 Creating... access to the Internet • Creating and configuring virtual web sites for the Apache Web server • Managing databases, tables, and fields in a MySQL or PostgreSQL database server • Sharing files with Windows systems by configuring Samba These are just a few of the available functions Webmin lets you configure almost all of the common services and popular servers on UNIX systems using a simple web interface... most Linux distributions as standard, or can be freely downloaded and installed 1.2 Who Should Use Webmin? Webmin was written for use by people who have some Linux experience but are not familiar with the intricacies of system administration Even though it makes the process of creating UNIX users or managing the Squid proxy server easy, you must first have some idea of what a UNIX account is and what... The Procmail Mail Filter Module 606 Setting Up Sendmail 606 Creating and Editing Actions 608 Creating and Editing Variable Assignments 611 Conditional Blocks and Include Files 612 Filtering Spam with SpamAssassin 613 Configuring the Procmail Mail Filter Module 614 Summary 614 46 Creating SSL Tunnels 615 Introduction to SSL and STunnel 615 The SSL Tunnels Module 616 Creating and Editing SSL Tunnels 617 . Linux ® Systems with Webmin ™ System Administration and Module Development Jamie Cameron Library of Congress Cataloging-in-Publication Data Cameron, Jamie. Managing. Commands 34 Module Access Control 34 Other Operating Systems 37 Summary 38 5 Disk and Network Filesystems 39 Introduction to Filesystems 39 The Disk and Network