Practical firewalls

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Title:

Practical firewalls

Personal Author:

Ogletree, Terry William

Publication Information:

Indianapolis : QUE, 2000

ISBN:

9780789724168

Subject Term:

Computers -- Access control

Firewalls (Computer security)

Available:*

Library	Item Barcode	Call Number	Material Type	Item Category 1	Status
Searching... PSZ JB	30000010053525	QA76.9.A25 O35 2000	Open Access Book	Book	Searching... Unknown

Summary

A firewall's purpose is to keep hackers out of networks. This book is aimed at network adminstrators charged with building and maintaining a firewall.

Author Notes

Terry Ogletree is a consultant. He has worked with computers since 1980. Terry has worked with UNIX and TCP/IP since 1985 and has been involved with Windows NT since it first appeared. He is the lead author for Upgrading and Repairing Networks, 2nd Edition (Que), and has contributed chapters to Special Edition Using UNIX, Third Edition (Que) and Windows NT Server Unleashed (SAMS).

Introduction	p. 1
I Understanding Firewalls and Internet Security	p. 7
1 Firewall Basics	p. 9
Why You Need a Firewall	p. 10
What Is a Firewall?	p. 10
It's a Jungle Out There!	p. 12
Use Your Site's Security Policy to Design the Firewall	p. 12
New Security Threats to Consider	p. 13
Decide Which Services You Will Provide for Your Users	p. 14
Firewall Policy	p. 16
Firewall Technologies	p. 16
The First Firewalls: Packet Filtering	p. 17
Using Application Gateways	p. 17
Other Firewall Components	p. 18
Hardware or Software Firewalls? Build or Buy?	p. 18
Operating System Concerns	p. 19
What a Firewall Can Do	p. 21
What a Firewall Cannot Protect You From	p. 21
Maintaining a Firewall	p. 23
Summary	p. 24
2 Introduction to the TCP/IP Protocol Suite	p. 25
The OSI Networking Model	p. 26
Physical Layer	p. 28
Data Link Layer	p. 28
Network Layer	p. 28
Transport Layer	p. 29
Session Layer	p. 29
Presentation Layer	p. 30
Application Layer	p. 30
How Does TCP/IP Fit into the OSI Model?	p. 30
TCP/IP Protocols	p. 31
The Internet Protocol (IP)	p. 31
The Transmission Control Protocol (TCP)	p. 32
Other Related Protocols	p. 33
IP Addressing	p. 36
IP Address Classes	p. 36
Class A Addresses	p. 38
Class B Addresses	p. 39
Class C Addresses	p. 39
Broadcast and Multicast Addresses	p. 40
What Are Subnets?	p. 41
Examining the Contents of an IP Datagram	p. 45
Important Packet Header Information	p. 47
What Are TCP and UDP Ports?	p. 49
Well-Known Ports	p. 49
Registered Ports	p. 50
Common TCP/IP Services	p. 50
Telnet	p. 50
The File Transfer Protocol (FTP)	p. 51
The Trivial File Transfer Protocol (TFTP)	p. 52
The Domain Name Service (DNS)	p. 52
Primary, Secondary, and Caching-Only Name Servers	p. 54
The Simple Mail Transport Protocol (SMTP)	p. 60
The r Utilities	p. 60
Other Network Services	p. 62
Summary	p. 62
3 Security and the Internet	p. 63
LANS and WANS	p. 64
Security in the Local Area Network	p. 64
User Authentication	p. 64
Resource Protections	p. 66
Physical Safeguards	p. 67
Security in Wide Area Networks	p. 67
Network Protocol Backdoors and Holes	p. 68
What Is Source Routing and Why Is It Not a Good Idea?	p. 69
Denial-of-Service Attacks	p. 69
SYN Flooding	p. 70
ICMP Redirects and Other ICMP Problems	p. 72
Ping of Death	p. 74
Distributed Denial-of-Service Attacks	p. 74
Packet Fragmentation	p. 76
Viruses and Trojan Horses	p. 78
Forged Email	p. 78
Break-Ins	p. 79
Password Theft	p. 80
Friendly Customer Service (Social Engineering)	p. 80
Backdoors	p. 81
Snooping: Monitoring Network Traffic	p. 81
IP Spoofing and Impersonation	p. 82
Summary	p. 83
4 Firewall Security Policy and Firewall Design Strategies	p. 85
The Design Comes Before the Firewall	p. 86
Your Company's Security Policy	p. 86
The Firewall Policy	p. 91
Firewall Strategies	p. 93
Using a Packet Filter	p. 94
Using an Application Proxy Gateway	p. 96
Combinations	p. 97
Using a Screened Subnet to Create a Demilitarized Zone (DMZ)	p. 101
Using Bastion Hosts and Sacrificial Hosts	p. 104
Incident Reporting and Response	p. 105
Keeping Up-to-date on Security Advisories	p. 106
Summary	p. 107
5 Packet Filtering	p. 109
The First Line of Defense	p. 110
Where to Use Packet Filters	p. 110
Creating Packet Filtering Rules	p. 113
Dangerous Services	p. 115
IP Header Information That Can Be Used to Filter Packets	p. 116
TCP and UDP Header Information	p. 117
Ports and Sockets	p. 120
The SYN Bit	p. 123
The ACK Bit	p. 123
ICMP Packets	p. 124
Stateless Operation Versus Stateful Inspection	p. 125
Hardware and Software Packet Filters	p. 126
Using a Router to Restrict Access	p. 126
Using a Dual-Homed Host to Restrict Access	p. 127
Advantages and Disadvantages of Packet Filters	p. 128
Summary	p. 129
6 Using a Bastion Host	p. 131
Configuring a Bastion Host	p. 132
Installing a Secure Operating System from Scratch	p. 133
Eliminating Unnecessary Services and Applications	p. 134
UNIX	p. 135
Other UNIX Network Files to Review	p. 138
Windows NT	p. 139
Removing Unnecessary Applications and Files	p. 141
Resource Protections and Access Control	p. 142
UNIX Resource Permissions	p. 142
Windows NT	p. 147
Configuring Auditing and Logging	p. 152
Running Proxy Software on the Bastion Host	p. 153
When the Bastion Host Is Compromised	p. 154
Summary	p. 155
7 Application Gateways and Proxy Servers	p. 157
Disable Routing on the Proxy Server	p. 160
Advantages and Disadvantages of Proxy Servers	p. 161
Classical and Transparent Proxies	p. 162
Classical Proxies	p. 162
Transparent Proxies	p. 163
Classical Proxies Can Hide DNS Information About Your Network	p. 165
Creating a Custom Proxy Application	p. 166
Network Address Translators (NATs)	p. 166
Basic NAT	p. 167
Network Address Port Translation (NAPT)	p. 168
Using NAT to Hide Information About the LAN	p. 169
Using NAT to Increase the LAN Address Space	p. 170
What Is Address Vectoring?	p. 170
Content Screening and Blocking	p. 171
Logging and Alerting Facilities	p. 173
Client Considerations	p. 174
Summary	p. 175
8 Operating System Monitoring and Auditing Techniques	p. 177
What Is Auditing?	p. 178
Reviewing Those Log Files!	p. 178
The Front End of Auditing: Resource Protections	p. 181
UNIX	p. 181
Using the syslog Utility	p. 181
Miscellaneous UNIX Log Files	p. 185
Windows NT	p. 188
Setting Up Auditing Events	p. 189
Using the Event Viewer to Review Log Files	p. 193
Managing Event Log Files	p. 195
Application-Specific Log Files	p. 196
Other Considerations	p. 196
Summary	p. 196
II Encryption and Secure Communications on the Internet	p. 197
9 Encryption Technology	p. 199
Protecting Sensitive Information	p. 200
What Is Encryption?	p. 201
Single Key Encryption	p. 201
Public Key Encryption	p. 202
Hybrids	p. 203
Practical Applications for Cryptography on the Internet	p. 204
What Are Digital Signatures?	p. 204
Digital Certificates	p. 206
The Secure Sockets Layer (SSL) Protocol	p. 207
Is That Web Page Using Encryption?	p. 209
Summary	p. 210
10 Virtual Private Networks (VPNs) and Tunneling	p. 211
Secure Communications on the Internet	p. 212
What Is a Virtual Private Network (VPN)?	p. 212
What Can a VPN Do?	p. 214
Disadvantages of VPNs	p. 215
The IPSec Protocol Suite	p. 216
Internet Key Exchange (IKE)	p. 217
The Authentication Header (AH)	p. 219
Encapsulation Security Payload (ESP)	p. 221
AH and ESP	p. 221
The Point-to-Point Tunneling Protocol (PPTP)	p. 222
The PPTP Control Connection	p. 223
Data Transmission Using PPTP Tunnel	p. 224
Layer Two Tunneling Protocol (L2TP)	p. 225
Summary	p. 225
11 Using Pretty Good Privacy (PGP) for Encryption	p. 227
Securing Information Transfers on the Internet	p. 228
Installing PGP	p. 229
Installing PGP on UNIX Systems	p. 229
Installing PGP on Windows NT	p. 233
Summary	p. 238
III Firewall Installation and Configuration	p. 239
12 Firewall Tools Available on the Internet	p. 241
Using Freeware and Shareware Products	p. 242
TCP Wrappers	p. 242
The TIS Firewall Toolkit	p. 244
SOCKS	p. 246
SQUID	p. 247
Drawbridge	p. 248
SATAN	p. 250
Other Handy Security Software	p. 252
Summary	p. 252
13 Using TCP Wrappers	p. 253
Introduction to TCP Wrappers	p. 254
How TCP Wrappers Works	p. 255
Logging via syslogd	p. 255
Obtaining TCP Wrappers	p. 256
Configuring TCP Wrappers	p. 256
Configuring the inetd.conf File	p. 257
The hosts.allow and hosts.deny Files	p. 258
Limitations of TCP Wrappers	p. 261
Summary	p. 262
14 Using the TIS Firewall Toolkit (FWTK)	p. 263
Building a Firewall Using the Toolkit	p. 264
A Short History of the Toolkit	p. 264
Obtaining FWTK	p. 264
How Does Gauntlet Firewall Differ from FWTK?	p. 265
FWTK Components	p. 266
netacl	p. 267
The Configuration File: /usr/local/etc/netperm-table	p. 272
Configuring Proxy Services	p. 275
FTP: ftp-gw	p. 275
Remote Logins and Telnet: tn-gw and rlogin-gw	p. 279
SMTP: smap	p. 282
Configuring Other Services: plug-gw	p. 285
Other FWTK Components	p. 289
Installing the Toolkit on a Bastion Host	p. 289
Summary	p. 290
15 SOCKS	p. 291
SOCKS V4 and SOCKS V5	p. 292
Version 4	p. 292
Version 5	p. 296
SOCKSified Applications	p. 298
SocksCap	p. 298
How to Get SOCKS	p. 299
SOCKS Support	p. 299
Summary	p. 300
16 SQUID	p. 301
What Is SQUID?	p. 302
Where to Get SQUID	p. 303
Installing and Configuring SQUID	p. 303
Choosing a SQUID Server	p. 303
Installing the Software	p. 304
Managing SQUID	p. 305
The squid.conf file	p. 305
The squid Command	p. 306
SQUID Log Files	p. 308
What Is the SQUID Cache Hierarchy?	p. 309
Configuring Clients to Use SQUID	p. 310
Summary	p. 311
17 Using ipfwadm and ipchains on Linux	p. 313
What Are ipfwadm and ipchains?	p. 314
Installing and Configuring ipfwadm	p. 315
Obtaining ipfwadm	p. 315
Installing ipfwadm	p. 316
Using ipfwadm Commands	p. 316
Place ipfwadm Rules in a Startup File	p. 321
Installing and Configuring ipchains	p. 321
Obtaining ipchains	p. 322
How ipchains Differs from ipfwadm	p. 322
Creating and Deleting Chains	p. 323
Summary	p. 331
18 Microsoft Proxy Server	p. 333
Overview of Microsoft Proxy Server	p. 334
Installing and Configuring Microsoft Proxy Server 2.0	p. 335
Running Setup	p. 336
Using the Internet Service Manager	p. 340
Packet Filter Properties	p. 341
Web Proxy Service Properties	p. 343
Configuration Management on the
Service Property Page	p. 346
Managing Permissions For the Web Proxy Services	p. 346
Managing the Caching Properties of the Service	p. 347
Routing Within Proxy Arrays	p. 350
Using the Publishing Property	p. 350
Setting Real Time Alerts and Logging Options	p. 351
Client Software Configuration Issues	p. 353
Summary	p. 355
19 The Elron CammandView Firewall	p. 357
Overview	p. 358
Installing CommandView Firewall	p. 358
Running the Setup Program	p. 360
The Command View Firewall Manager Application	p. 364
File Menu and View Menu	p. 365
Firewall Menu Options	p. 367
Logs Menu Options	p. 368
Managing User Services	p. 368
Where to Go from Here	p. 369
Summary	p. 370
20 Firewall Appliances	p. 371
What Is a Firewall Appliance?	p. 372
Quick, Easy Installation	p. 373
Simple Management Interface	p. 373
Self-Contained Device	p. 374
Multiple Network Interfaces	p. 374
Default Security Policies	p. 375
Packet Filtering and Application Proxies	p. 376
Network Address Translation (NAT)	p. 376
Reporting and Alerting	p. 377
Virtual Private Networking (VPN)	p. 378
Pricing a Firewall Appliance	p. 378
Summary	p. 379
21 Firewalls and Beyond	p. 381
New Functionality	p. 382
Firewall Integration	p. 383
Firewall Testing	p. 384
Home Computers	p. 384
Virtual Private Network Clients	p. 385
IPv6: The Next Generation IP Protocol	p. 386
The IPv6 Header	p. 386
Extension Headers	p. 389
IPv6 Addressing	p. 391
The Transition to IPv6	p. 391
Summary	p. 392
IV Appendixes	p. 393
A TCP and UDP Common Ports	p. 395
B Other Security Tools You Can Use	p. 445
C Additional Resources	p. 455

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Summary

Author Notes

Table of Contents