Network Security

480 Pages·2006·7.75 MB·English

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NETWORK
SECURITY
HACKS
TM
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SECOND EDITION
NETWORK
SECURITY
HACKS
TM
Andrew Lockhart
Beijing • Cambridge • Farnham • Köln • Paris • Sebastopol • Taipei • Tokyo
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Network Security Hacks™, Second Edition
by Andrew Lockhart
Copyright © 2007, 2004 O’Reilly Media, Inc. All rights reserved.
Printed in the United States of America.
Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North,
Sebastopol, CA 95472.
O’Reilly books may be purchased for educational, business, or sales promotional use. Online
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corporate/institutional sales department: [phone] [email protected].
Editor: Brian Sawyer Cover Designer: Karen Montgomery
Production Editor: Philip Dangler Interior Designer: David Futato
Copyeditor: Rachel Wheeler Illustrators: Robert Romano
Indexer: Ellen Troutman-Zaig and Jessamyn Read
Printing History:
April 2004: First Edition.
November 2006: Second Edition.
NutshellHandbook,theNutshellHandbooklogo,andtheO’Reillylogoareregisteredtrademarks
ofO’ReillyMedia,Inc.TheHacksseriesdesignations,NetworkSecurityHacks,theimageofbarbed
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While every precaution has been taken in the preparation of this book, the publisher and author
assume no responsibility for errors or omissions, or for damages resulting from the use of the
information contained herein.
Small print:The technologies discussed in this publication, the limitations on these technologies
thattechnologyandcontentownersseektoimpose,andthelawsactuallylimitingtheuseofthese
technologies are constantly changing. Thus, some of the hacks described in this publication may
notwork,maycauseunintendedharmtosystemsonwhichtheyareused,ormaynotbeconsistent
withapplicableuseragreements.Youruseofthesehacksisatyourownrisk,andO’ReillyMedia,
Inc.disclaimsresponsibilityforanydamageorexpenseresultingfromtheiruse.Inanyevent,you
should take care that your use of these hacks does not violate any applicable laws, including
copyright laws.
This book uses RepKover™, a durable and flexible lay-flat binding.
ISBN 10: 0-596-52763-2
ISBN 13: 978-0-596-52763-1
[C]
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Contents
Credits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Chapter1. Unix Host Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.Secure Mount Points 2
2.Scan for SUID and SGID Programs 3
3.Scan for World- and Group-Writable Directories 5
4.Create Flexible Permissions Hierarchies with POSIX ACLs 5
5.Protect Your Logs from Tampering 9
6.Delegate Administrative Roles 11
7.Automate Cryptographic Signature Verification 13
8.Check for Listening Services 15
9.Prevent Services from Binding to an Interface 17
10.Restrict Services with Sandboxed Environments 19
11.Use proftpd with a MySQL Authentication Source 23
12.Prevent Stack-Smashing Attacks 26
13.Lock Down Your Kernel with grsecurity 28
14.Restrict Applications with grsecurity 33
15.Restrict System Calls with systrace 36
16.Create systrace Policies Automatically 39
17.Control Login Access with PAM 41
18.Restrict Users to SCP and SFTP 46
19.Use Single-Use Passwords for Authentication 49
20.Restrict Shell Environments 52
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21.Enforce User and Group Resource Limits 54
22.Automate System Updates 55
Chapter2. Windows Host Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
23.Check Servers for Applied Patches 59
24.Use Group Policy to Configure Automatic Updates 63
25.List Open Files and Their Owning Processes 66
26.List Running Services and Open Ports 68
27.Enable Auditing 69
28.Enumerate Automatically Executed Programs 71
29.Secure Your Event Logs 73
30.Change Your Maximum Log File Sizes 73
31.Back Up and Clear the Event Logs 75
32.Disable Default Shares 78
33.Encrypt Your Temp Folder 79
34.Back Up EFS 80
35.Clear the Paging File at Shutdown 86
36.Check for Passwords That Never Expire 88
Chapter3. Privacy and Anonymity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
37.Evade Traffic Analysis 91
38.Tunnel SSH Through Tor 95
39.Encrypt Your Files Seamlessly 96
40.Guard Against Phishing 100
41.Use the Web with Fewer Passwords 105
42.Encrypt Your Email with Thunderbird 107
43.Encrypt Your Email in Mac OS X 112
Chapter4. Firewalling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
44.Firewall with Netfilter 117
45.Firewall with OpenBSD’s PacketFilter 122
46.Protect Your Computer with the Windows Firewall 128
47.Close Down Open Ports and Block Protocols 137
48.Replace the Windows Firewall 139
49.Create an Authenticated Gateway 147
50.Keep Your Network Self-Contained 149
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51.Test Your Firewall 151
52.MAC Filter with Netfilter 154
53.Block Tor 156
Chapter5. Encrypting and Securing Services . . . . . . . . . . . . . . . . . . . . . . . 158
54.Encrypt IMAP and POP with SSL 158
55.Use TLS-Enabled SMTP with Sendmail 161
56.Use TLS-Enabled SMTP with Qmail 163
57.Install Apache with SSL and suEXEC 164
58.Secure BIND 169
59.Set Up a Minimal and Secure DNS Server 172
60.Secure MySQL 176
61.Share Files Securely in Unix 178
Chapter6. Network Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
62.Detect ARP Spoofing 184
63.Create a Static ARP Table 186
64.Protect Against SSH Brute-Force Attacks 188
65.Fool Remote Operating System Detection Software 190
66.Keep an Inventory of Your Network 194
67.Scan Your Network for Vulnerabilities 197
68.Keep Server Clocks Synchronized 207
69.Create Your Own Certificate Authority 209
70.Distribute Your CA to Clients 213
71.Back Up and Restore a Certificate Authority with Certificate
Services 214
72.Detect Ethernet Sniffers Remotely 221
73.Help Track Attackers 227
74.Scan for Viruses on Your Unix Servers 229
75.Track Vulnerabilities 233
Chapter7. Wireless Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
76.Turn Your Commodity Wireless Routers into a Sophisticated
Security Platform 236
77.Use Fine-Grained Authentication for Your Wireless Network 240
78.Deploy a Captive Portal 244
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Chapter8. Logging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
79.Run a Central Syslog Server 251
80.Steer Syslog 252
81.Integrate Windows into Your Syslog Infrastructure 254
82.Summarize Your Logs Automatically 262
83.Monitor Your Logs Automatically 263
84.Aggregate Logs from Remote Sites 266
85.Log User Activity with Process Accounting 272
86.Centrally Monitor the Security Posture of Your Servers 273
Chapter9. Monitoring and Trending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
87.Monitor Availability 283
88.Graph Trends 291
89.Get Real-Time Network Stats 293
90.Collect Statistics with Firewall Rules 295
91.Sniff the Ether Remotely 297
Chapter10. Secure Tunnels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
92.Set Up IPsec Under Linux 301
93.Set Up IPsec Under FreeBSD 306
94.Set Up IPsec in OpenBSD 309
95.Encrypt Traffic Automatically with Openswan 314
96.Forward and Encrypt Traffic with SSH 316
97.Automate Logins with SSH Client Keys 318
98.Use a Squid Proxy over SSH 320
99.Use SSH As a SOCKS Proxy 322
100.Encrypt and Tunnel Traffic with SSL 324
101.Tunnel Connections Inside HTTP 327
102.Tunnel with VTun and SSH 329
103.Generate VTun Configurations Automatically 334
104.Create a Cross-Platform VPN 339
105.Tunnel PPP 345
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