Novell LINUX ENTERPRISE DESKTOP 11 Manuale utente

SUSE Linux Enterprise

Server

www.novell.com11

March17,2009 Security Guide

Security Guide

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Contents

About This Guide xi

1Security and Condentiality 1

1.1 Local Security and Network Security . . . . . . . . . . . . . . . . . 2

1.2 Some General Security Tips and Tricks . . . . . . . . . . . . . . . . 11

1.3 Using the Central Security Reporting Address . . . . . . . . . . . . . 14

Part I Authentication 15

2Authentication with PAM 17

2.1 Structure of a PAM Conguration File . . . . . . . . . . . . . . . . 18

2.2 The PAM Conguration of sshd . . . . . . . . . . . . . . . . . . . 20

2.3 Conguration of PAM Modules . . . . . . . . . . . . . . . . . . . 22

2.4 Conguring PAM Using pam-cong . . . . . . . . . . . . . . . . . 24

2.5 For More Information . . . . . . . . . . . . . . . . . . . . . . . 26

3Using NIS 27

3.1 Conguring NIS Servers . . . . . . . . . . . . . . . . . . . . . . 27

3.2 Conguring NIS Clients . . . . . . . . . . . . . . . . . . . . . . 33

4LDAP—A Directory Service 35

4.1 LDAPversusNIS......................... 36

4.2 Structure of an LDAP Directory Tree . . . . . . . . . . . . . . . . . 37

4.3 Conguring an LDAP Server with YaST . . . . . . . . . . . . . . . . 40

4.4 Conguring an LDAP Client with YaST . . . . . . . . . . . . . . . . 49

4.5 Conguring LDAP Users and Groups in YaST . . . . . . . . . . . . . . 57

4.6 Browsing the LDAP Directory Tree . . . . . . . . . . . . . . . . . . 59

4.7 Manually Conguring an LDAP Server . . . . . . . . . . . . . . . . 60

4.8 Manually Administering LDAP Data . . . . . . . . . . . . . . . . . 61

4.9 For More Information . . . . . . . . . . . . . . . . . . . . . . . 65

5Active Directory Support 67

5.1 Integrating Linux and AD Environments . . . . . . . . . . . . . . . . 67

5.2 Background Information for Linux AD Support . . . . . . . . . . . . 68

5.3 Conguring a Linux Client for Active Directory . . . . . . . . . . . . 74

5.4 Logging In to an AD Domain . . . . . . . . . . . . . . . . . . . . 77

5.5 Changing Passwords . . . . . . . . . . . . . . . . . . . . . . . . 79

6Network Authentication with Kerberos 81

6.1 Kerberos Terminology . . . . . . . . . . . . . . . . . . . . . . . 82

6.2 How Kerberos Works . . . . . . . . . . . . . . . . . . . . . . . 83

6.3 Users' View of Kerberos . . . . . . . . . . . . . . . . . . . . . . 86

6.4 Installing and Administering Kerberos . . . . . . . . . . . . . . . . 87

6.5 For More Information . . . . . . . . . . . . . . . . . . . . . . 108

7Using the Fingerprint Reader 109

7.1 Supported Applications and Actions . . . . . . . . . . . . . . . . 109

7.2 Managing Fingerprints with YaST . . . . . . . . . . . . . . . . . . 110

Part II Local Security 113

8Conguring Security Settings with YaST 115

8.1 Security Overview . . . . . . . . . . . . . . . . . . . . . . . . 115

8.2 Predened Security Congurations . . . . . . . . . . . . . . . . . 116

8.3 Password Settings . . . . . . . . . . . . . . . . . . . . . . . . 117

8.4 BootSettings.......................... 118

8.5 LoginSettings.......................... 118

8.6 UserAddition.......................... 119

8.7 Miscellaneous Settings . . . . . . . . . . . . . . . . . . . . . . 119

9PolicyKit 121

9.1 Available Policies and Supported Applications . . . . . . . . . . . . 121

9.2 Authorization Types . . . . . . . . . . . . . . . . . . . . . . . 122

9.3 Modifying and Setting Privileges . . . . . . . . . . . . . . . . . . 123

10 Access Control Lists in Linux 131

10.1 Traditional File Permissions . . . . . . . . . . . . . . . . . . . . 131

10.2 Advantages of ACLs . . . . . . . . . . . . . . . . . . . . . . . 133

10.3 Denitions........................... 133

10.4 HandlingACLs.......................... 134

10.5 ACL Support in Applications . . . . . . . . . . . . . . . . . . . . 142

10.6 For More Information . . . . . . . . . . . . . . . . . . . . . . 143

11 Encrypting Partitions and Files 145

11.1 Setting Up an Encrypted File System with YaST . . . . . . . . . . . . 146

11.2 Using Encrypted Home Directories . . . . . . . . . . . . . . . . . 149

11.3 Using vi to Encrypt Single ASCII Text Files . . . . . . . . . . . . . . 150

12 Certicate Store 151

12.1 Activating Certicate Store . . . . . . . . . . . . . . . . . . . . 151

12.2 Importing Certicates . . . . . . . . . . . . . . . . . . . . . . 152

13 Intrusion Detection with AIDE 153

13.1 Setting Up a AIDE Database . . . . . . . . . . . . . . . . . . . . 153

13.2 Local AIDE Checks . . . . . . . . . . . . . . . . . . . . . . . . 156

13.3 System Independent Checking . . . . . . . . . . . . . . . . . . . 157

13.4 For More Information . . . . . . . . . . . . . . . . . . . . . . 158

Part III Network Security 159

14 SSH: Secure Network Operations 161

14.1 The OpenSSH Package . . . . . . . . . . . . . . . . . . . . . . 161

14.2 ThesshProgram......................... 162

14.3 scp—SecureCopy........................ 162

14.4 sftp—Secure File Transfer . . . . . . . . . . . . . . . . . . . . . 163

14.5 The SSH Daemon (sshd)—Server-Side . . . . . . . . . . . . . . . . 163

14.6 SSH Authentication Mechanisms . . . . . . . . . . . . . . . . . . 164

14.7 X, Authentication, and Forwarding Mechanisms . . . . . . . . . . . . 166

14.8 Conguring An SSH Daemon with YaST . . . . . . . . . . . . . . . 167

15 Masquerading and Firewalls 169

15.1 Packet Filtering with iptables . . . . . . . . . . . . . . . . . . . . 169

15.2 Masquerading Basics . . . . . . . . . . . . . . . . . . . . . . . 172

15.3 Firewalling Basics . . . . . . . . . . . . . . . . . . . . . . . . 173

15.4 SuSErewall2.......................... 174

15.5 For More Information . . . . . . . . . . . . . . . . . . . . . . 179

16 Conguring VPN Server 181

16.1 Overview............................ 181

16.2 Creating the Simplest VPN Example . . . . . . . . . . . . . . . . . 185

16.3 Setting Up Your VPN Server Using Certicate Authority . . . . . . . . 187

16.4 KDE- and GNOME Applets For Clients . . . . . . . . . . . . . . . . 193

16.5 For More Information . . . . . . . . . . . . . . . . . . . . . . 195

17 Managing X.509 Certication 197

17.1 The Principles of Digital Certication . . . . . . . . . . . . . . . . 197

17.2 YaST Modules for CA Management . . . . . . . . . . . . . . . . . 202

Part IV Conning Privileges with Novell AppArmor 215

18 Introducing AppArmor 217

18.1 Background Information on AppArmor Proling . . . . . . . . . . . 218

19 Getting Started 219

19.1 Installing Novell AppArmor . . . . . . . . . . . . . . . . . . . . 220

19.2 Enabling and Disabling Novell AppArmor . . . . . . . . . . . . . . 220

19.3 Choosing the Applications to Prole . . . . . . . . . . . . . . . . 221

19.4 Building and Modifying Proles . . . . . . . . . . . . . . . . . . 222

19.5 Conguring Novell AppArmor Event Notication and Reports . . . . . 224

19.6 Updating Your Proles . . . . . . . . . . . . . . . . . . . . . . 226

20 Immunizing Programs 227

20.1 Introducing the AppArmor Framework . . . . . . . . . . . . . . . 228

20.2 Determining Programs to Immunize . . . . . . . . . . . . . . . . 230

20.3 Immunizing cron Jobs . . . . . . . . . . . . . . . . . . . . . . . 231

20.4 Immunizing Network Applications . . . . . . . . . . . . . . . . . 232

21 Prole Components and Syntax 237

21.1 Breaking a Novell AppArmor Prole into Its Parts . . . . . . . . . . . 238

21.2 ProleTypes.......................... 241

21.3 #include Statements . . . . . . . . . . . . . . . . . . . . . . . 244

21.4 Capability Entries (POSIX.1e) . . . . . . . . . . . . . . . . . . . . 245

21.5 Network Access Control . . . . . . . . . . . . . . . . . . . . . 245

21.6 Paths and Globbing . . . . . . . . . . . . . . . . . . . . . . . 246

21.7 File Permission Access Modes . . . . . . . . . . . . . . . . . . . 249

21.8 ExecuteModes......................... 252

21.9 Resource Limit Control . . . . . . . . . . . . . . . . . . . . . . 257

21.10AuditingRules.......................... 258

21.11 Setting Capabilities per Prole . . . . . . . . . . . . . . . . . . . 259

22 AppArmor Prole Repositories 261

22.1 Using the Local Repository . . . . . . . . . . . . . . . . . . . . 261

22.2 Using the External Repository . . . . . . . . . . . . . . . . . . . 262

23 Building and Managing Proles with YaST 265

23.1 Adding a Prole Using the Wizard . . . . . . . . . . . . . . . . . 267

23.2 Manually Adding a Prole . . . . . . . . . . . . . . . . . . . . . 275

23.3 EditingProles ......................... 275

23.4 Deleting a Prole . . . . . . . . . . . . . . . . . . . . . . . . 281

23.5 Updating Proles from Log Entries . . . . . . . . . . . . . . . . . 281

23.6 Managing Novell AppArmor and Security Event Status . . . . . . . . . 283

24 Building Proles from the Command Line 287

24.1 Checking the AppArmor Module Status . . . . . . . . . . . . . . . 287

24.2 Building AppArmor Proles . . . . . . . . . . . . . . . . . . . . 289

24.3 Adding or Creating an AppArmor Prole . . . . . . . . . . . . . . 290

24.4 Editing an AppArmor Prole . . . . . . . . . . . . . . . . . . . . 290

24.5 Deleting an AppArmor Prole . . . . . . . . . . . . . . . . . . . 290

24.6 Two Methods of Proling . . . . . . . . . . . . . . . . . . . . . 291

24.7 Important Filenames and Directories . . . . . . . . . . . . . . . . 312

25 Proling Your Web Applications Using ChangeHat 315

25.1 Apache ChangeHat . . . . . . . . . . . . . . . . . . . . . . . . 316

25.2 Conguring Apache for mod_apparmor . . . . . . . . . . . . . . . 322

26 Conning Users with pam_apparmor 327

27 Managing Proled Applications 329

27.1 Monitoring Your Secured Applications . . . . . . . . . . . . . . . 329

27.2 Conguring Security Event Notication . . . . . . . . . . . . . . . 330

27.3 Conguring Reports . . . . . . . . . . . . . . . . . . . . . . . 333

27.4 Conguring and Using the AppArmor Desktop Monitor Applet . . . . . 353

27.5 Reacting to Security Event Rejections . . . . . . . . . . . . . . . . 354

27.6 Maintaining Your Security Proles . . . . . . . . . . . . . . . . . 354

28 Support 357

28.1 Updating Novell AppArmor Online . . . . . . . . . . . . . . . . . 357

28.2 Using the Man Pages . . . . . . . . . . . . . . . . . . . . . . . 357

28.3 For More Information . . . . . . . . . . . . . . . . . . . . . . 359

28.4 Troubleshooting......................... 360

28.5 Reporting Bugs for AppArmor . . . . . . . . . . . . . . . . . . . 367

29 AppArmor Glossary 369

Part V The Linux Audit Framework 373

30 Understanding Linux Audit 375

30.1 Introducing the Components of Linux Audit . . . . . . . . . . . . . 378

30.2 Conguring the Audit Daemon . . . . . . . . . . . . . . . . . . . 379

30.3 Controlling the Audit System Using auditctl . . . . . . . . . . . . . 385

30.4 Passing Parameters to the Audit System . . . . . . . . . . . . . . . 387

30.5 Understanding the Audit Logs and Generating Reports . . . . . . . . . 391

30.6 Querying the Audit Daemon Logs with ausearch . . . . . . . . . . . 403

30.7 Analyzing Processes with autrace . . . . . . . . . . . . . . . . . . 407

30.8 Visualizing Audit Data . . . . . . . . . . . . . . . . . . . . . . 408

31 Setting Up the Linux Audit Framework 411

31.1 Determining the Components to Audit . . . . . . . . . . . . . . . 412

31.2 Conguring the Audit Daemon . . . . . . . . . . . . . . . . . . . 413

31.3 Enabling Audit for System Calls . . . . . . . . . . . . . . . . . . 414

31.4 Setting Up Audit Rules . . . . . . . . . . . . . . . . . . . . . . 415

31.5 Conguring Audit Reports . . . . . . . . . . . . . . . . . . . . . 417

31.6 Conguring Log Visualization . . . . . . . . . . . . . . . . . . . 420

32 Introducing an Audit Rule Set 423

32.1 Adding Basic Audit Conguration Parameters . . . . . . . . . . . . 424

32.2 Adding Watches on Audit Log Files and Conguration Files . . . . . . . 425

32.3 Monitoring File System Objects . . . . . . . . . . . . . . . . . . 426

32.4 Monitoring Security Conguration Files and Databases . . . . . . . . . 427

32.5 Monitoring Miscellaneous System Calls . . . . . . . . . . . . . . . 430

32.6 Filtering System Call Arguments . . . . . . . . . . . . . . . . . . 430

32.7 Managing Audit Event Records Using Keys . . . . . . . . . . . . . . 433

33 Useful Resources 435

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