Table of Contents

Introduction......................................................................................................................................... v

1. Document Conventions......................................................................................................... v

2. More to Come ....................................................................................................................viii

2.1. Send in Your Feedback .......................................................................................viii

I. A General Introduction to Security .............................................................................................. ix

1. Security Overview............................................................................................................... 11

1.1. What is Computer Security? ................................................................................ 11

1.2. Security Controls ................................................................................................. 15

1.3. Conclusion ........................................................................................................... 16

2. Attackers and Risks............................................................................................................. 17

2.1. Hackers and Crackers .......................................................................................... 17

2.2. Threats To Network Security ............................................................................... 17

2.3. Threats To Server Security................................................................................... 19

2.4. Threats To Workstation and Home PC Security .................................................. 21

II. Configuring Red Hat Linux for Security ................................................................................... 23

3. Security Updates ................................................................................................................. 25

3.1. Using Red Hat Network....................................................................................... 25

3.2. Using the Errata Website ..................................................................................... 25

4. Workstation Security........................................................................................................... 27

4.1. Evaluating Workstation Security ......................................................................... 27

4.2. BIOS and Boot Loader Security .......................................................................... 27

4.3. Password Security ................................................................................................ 30

4.4. Administrative Controls....................................................................................... 35

4.5. Available Network Services................................................................................. 40

4.6. Personal Firewalls ................................................................................................ 42

4.7. Security Enhanced Communication Tools........................................................... 43

5. Server Security.................................................................................................................... 45

5.1. Securing Services With TCP Wrappers and

xinetd

.......................................... 45

5.2. Securing Portmap................................................................................................. 47

5.3. Securing NIS........................................................................................................ 48

5.4. Securing NFS ....................................................................................................... 50

5.5. Securing Apache HTTP Server............................................................................ 51

5.6. Securing FTP ....................................................................................................... 52

5.7. Securing Sendmail ............................................................................................... 55

5.8. Verifying Which Ports Are Listening .................................................................. 56

6. Virtual Private Networks..................................................................................................... 59

6.1. VPNs and Red Hat Linux .................................................................................... 59

6.2. Crypto IP Encapsulation (CIPE).......................................................................... 59

7. Firewalls.............................................................................................................................. 67

7.1. Netfilter and

iptables

....................................................................................... 68

7.2.

ip6tables

.......................................................................................................... 72

7.3. Additional Resources ........................................................................................... 73

8. Hardware and Network Protection...................................................................................... 75

8.1. Secure Network Topologies ................................................................................. 75

8.2. Hardware Security ............................................................................................... 78

III. Assessing Your Security ............................................................................................................. 79

9. Vulnerability Assessment.................................................................................................... 81

9.1. Thinking Like the Enemy .................................................................................... 81

9.2. Defining Assessment and Testing ........................................................................ 81

9.3. Evaluating the Tools............................................................................................. 83