Introduction 1
About This Book 1
Conventions Used in This Book 2
Foolish Assumptions 2
How This Book Is Organized 3
Part I: TCP/IP from Names to Addresses 3
Part II: Getting Connected 3
Part III: Configuring Clients and Servers: Web, E-Mail, and Chat 4
Part IV: Even More TCP/IP Applications and Services 4
Part V: Network Troubleshooting and Security 4
Part VI: The Part of Tens 5
Icons Used in This Book 5
Where to Go from Here 6
Part I: TCP/IP from Names to Addresses 7
Chapter 1: Understanding TCP/IP Basics 9
Following Rules for the Internet: TCP/IP Protocols 10
Who’s in charge of the Internet and TCP/IP? 10
Checking out RFCs: The written rules 12
Examining Other Standards Organizations That Add to the Rules 13
Distinguishing Between the Internet, an Internet, and an Intranet 13
Extending Intranets to Extranets 14
Introducing Virtual Private Networks 15
Exploring Geographically Based Networks 16
Networks connected by wires and cables 16
Wireless networks 17
The geography of TCP/IP 17
Chapter 2: Layering TCP/IP Protocols 19
Taking a Timeout for Hardware 19
Starting with network connection media 20
Colliding with Ethernet 20
Stacking the TCP/IP Layers 22
Layer 1: The physical layer 23
Layer 2: The data link layer 24
Layer 3: The internet layer 24
Layer 4: The transport layer 24
Layer 5: The application layer 25
TCP/IP For Dummies, 6th Edition viii
Chewing through Network Layers: A Packet’s Journey 25
Understanding TCP/IP: More than just protocols 27
Determining whether your network has a protocol, an application, or a service 27
Plowing through the Protocol List (In Case You Thought Only Two Existed) 28
Physical layer protocols 29
Data link layer protocols 29
Internet layer protocols 29
Transport layer protocols 31
Application layer protocols 36
Chapter 3: Serving Up Clients and Servers 43
Understanding the Server Side 43
Examining the server’s job 44
Identifying types of servers 44
Using dedicated servers 45
Understanding the Client Side 45
Defining a client 45
Clients, clients everywhere 46
Answering the Question “Are You Being Served?” 46
Supporting TCP/IP with Client/Server and Vice Versa 47
Recognizing Other Internetworking Styles: Peer-to-Peer Computing 47
Determining whether peer-to-peer workgroups are still handy 48
P2P applications — P2P across the Internet 48
Chapter 4: Nice Names and Appetizing Addresses 51
What Did You Say Your Host’s Name Is? 52
Playing the numbers game 52
Identifying a computer as uniquely yours 53
Translating names into numbers 54
Taking a Closer Look at IP Addresses 54
Savoring Classful Addressing 55
Recognizing the Parts of an IP Address 56
Class A is for a few enormous networks 57
Class B is for lots of big networks 57
Class C is for millions of small networks 57
Class D is for multicasting 57
Biting Down on Bits and Bytes 58
Obtaining an IP Address 60
Choosing whether to go public or stay private 60
Obeying the network police 61
Obtaining a globally unique IP address 61
Acquiring a static address 62
Getting dynamic addresses with DHCP 62
Finding out your IP address 62
Table of Contents ix
Resolving Names and Addresses with DNS 64
Understanding the minimum amount of information about DNS 64
Using DNS to “Do Nifty Searches” 65
Describing Fully Qualified Domain Names (FQDNs) 65
Branching out into domains 66
Stalking new domains 68
Determining Whether the Internet Will Ever Fill Up 68
Choking on bandwidth 68
Panicking about not having enough addresses 69
Dishing Up More Kinds of Addresses 69
MAC: Media Access Control 69
Port numbers 70
Chapter 5: Need More Addresses? Try Subnetting and NAT 73
Working with Subnets and Subnet Masks 74
Defining subnet masks 76
Why a network has a mask when it has no subnets 76
Subnetting 101 77
Letting the DHCP Protocol Do the Work for You 79
One administrator’s nightmare is another’s fantasy 80
Understanding how the DHCP protocol works —it’s client/server again 81
Being evicted after your lease expires 82
Sharing Addresses with Network Address Translation (NAT) 83
Understanding how NAT works 83
Securing NAT 84
Using NAT and DHCP to work together 84
Swallowing NAT incompatibilities 86
Digesting NAT-PT (Network Address Translation-Protocol Translation) 87
Part II: Getting Connected 89
Chapter 6: Configuring a TCP/IP Network — the Software Side 91
Installing TCP/IP? Probably Not 91
Detecting whether TCP/IP is installed 92
Determining whether it’s IPv4, IPv6, or both 92
Savoring TCP/IP right out of the box 93
Six Steps to a Complete TCP/IP Configuration 94
Step 1: Determining whether your computer is a client or server or both 95
Step 2: Gathering client information 95
Step 3: Setting up your NIC(s) 95
TCP/IP For Dummies, 6th Edition x
Step 4: Deciding on a static IP address or a DHCP leased address 96
Step 5: Choosing how your host will translate names into IP addresses 97
Step 6: Gathering server information 97
Setting TCP/IP Client Properties 97
Configuring TCP/IP on a Mac OS X client 98
Configuring TCP/IP on a Linux or Unix client 100
Configuring a TCP/IP client on Windows Vista 102
Configuring a TCP/IP client on Windows XP 103
Setting TCP/IP Server Properties 104
Installing TCP/IP from Scratch 105
Feasting on Network Files 107
The local hosts file 107
The trusted hosts file, hostsequiv 109
Freddie’s nightmare: Your personal trust file 110
The services file 111
Daemons Aren’t Devils 113
Relishing your daemons113
Finding the daemons on your computer 113
Chapter 7: Networking SOHO with Wireless 115
Gulping the Minimum Hardware Details 116
NICs 116
Routers 117
Setting Up a Home Wireless Network in Four Steps 118
Step 1: Choose your wireless hardware 118
Step 2: Connect your wireless router 120
Step 3: Set up your wireless router 121
Step 4: Connect your computers 124
Securing Your Network 124
Securing the wired side 125
Securing the wireless side 125
Broadband for Everyone? We Hope 128
Level 1: Using wireless hotspots 128
Level 2: Paying for broadband wireless service 129
Level 3: Going anywhere you want to connect to the Internet with WiMAX 129
Chapter 8: Advancing into Routing Protocols 131
Understanding Routing Lingo 132
Routing Through the Layers — the Journey of a Packet 135
A new message heads out across the Net 135
The message visits the router 137
Into an Internet router and out again 139
Reaching the destination 140
Table of Contents xi
Getting a Handle on How Routers Work 143
Getting Started with Routers 146
Swallowing Routing Protocols 148
Nibbling on IGP protocols 149
Exterior Gateway Protocols (EGP) 152
Understanding How BGP Routers Work 154
Juicing Up Routing with CIDR 154
C Is for Classless 156
CIDR pressing the routing tables 157
You say “subnet,” aggregating.net says “aggregate” 159
Securing Your Router 159
Coring the apple with Denial of Service (DoS) Attacks 160
Hijacking routers 160
Eavesdropping on BGP 161
It’s so sad 161
S-BGP (Secure BGP): Proposals to make BGP routing secure 161
Chapter 9: IPv6: IP on Steroids 163
Say Hello to IPv6 163
Digesting IPv4 limitations 164
Absorbing IPv6 advantages 164
If It Ain’t Broke, Don’t Fix It — Unless It Can Be Improved 165
Wow! Eight Sections in an IPv6 Address? 165
Why use hexadecimal? 166
There’s good news and there’s bad news 166
Take advantage of IPv6 address shortcuts 167
Special IPv6 Addresses 169
IPv6 — and the Using Is Easy 169
Checking out the network with autodiscovery 170
Ensuring that your address is unique 171
Automatically assigning addresses 172
Realizing that autoregistration says “Let us serve you” 172
IPv6 Installation 173
Configuring IPv6 on Windows XP and Windows Server 2003 173
Welcoming IPv6 to Mac OS X175
Getting started with IPv6 in Unix and Linux 175
Other Delicious IPv6 Morsels 176
Security for all 176
Faster, better multimedia 178
Support for real-time applications 178
Improved support for mobile computing 178
Share the Planet — IPv6 and IPv4 Can Coexist 179
Stacking IPv4 and Iv6 179
Tunneling IPv6 through IPv4 180
Whew — You Made It! 180
TCP/IP For Dummies, 6th Edition xii
Chapter 10: Serving Up DNS (The Domain Name System) 181
Taking a Look at the DNS Components 182
Going Back to DNS Basics 183
Revisiting Client/Server with DNS 184
Dishing up DNS client/server definitions 184
Snacking on resolvers and name servers 184
Who’s in charge here? 186
Serving a DNS client’s needs 186
Oops! Can’t help you 187
Who’s Responsible for Name and Address Information? 187
Understanding Servers and Authority 189
Primary name server: Master of your domain 189
Secondary name servers 190
Caching servers 192
Understanding Domains and Zones 193
Problem Solving with Dynamic DNS (DYNDNS) 195
Diving into DNSSEC (DNS Security Extensions) 195
Why does DNS need DNSSEC? 196
Glimpsing behind the scenes of DNSSEC 197
Part III: Configuring Clients and Servers: Web, E-Mail, and Chat 199
Chapter 11: Digesting Web Clients and Servers 201
Standardizing Web Services 201
Deciphering the Languages of the Web 202
HTML 202
HTML 4 204
XML 205
XHTML 205
HTML + MIME = MHTML 205
Java and other Web dialects 205
Hypertext and hypermedia 206
Understanding How Web Browsing Works 207
Serving up a Web page 207
Storing user information as cookies 209
Managing cookies with your browser 210
Dishing up multimedia over the Internet 212
Feeding Web Pages with Atom and RSS 214
Reducing the Web’s Wide Waistline to Increase Speed 215
Proxy Serving for Speed and Security 218
Caching pages 219
Improving security with filtering 220
Setting up a proxy client 220
Finishing touches 223
Table of Contents xiii
Setting Up a Caching Proxy Server 223
Outlining the general steps for installing and configuring squid 223
Configuring squid for Microsoft Windows Server 2008 224
Browsing Securely 228
Ensuring that a site is secure 228
Using your browser’s security features 229
Setting Up a Web Server 230
Setting up the Apache HTTP Server 231
Speeding up Apache 234
Making Apache more secure 234
Adding Security to HTTP 235
Taking a look at HTTPS 236
Getting up to speed on SSL 236
Stepping through an SSL Transaction 237
Using Digital Certificates for Secure Web Browsing 238
Chapter 12: Minimum Security Facilities 239
What’s the Worst That Could Happen? 239
Jump-Starting Security with the Big Three 240
Installing a personal firewall 241
Vaccinating your system with the anti-s 242
Encrypting data so snoopers can’t read it 243
Adding a Few More Basic Protections 243
Chapter 13: Eating Up E-Mail 245
Getting the Big Picture about How E-Mail Works 245
Feasting on E-Mail’s Client-Server Delights 246
E-mail clients 246
E-mail clients versus Web mail clients 247
E-mail servers 247
Postfix: Configuring the fastest-growing MTA 249
Sharpening the Finer Points of Mail Servers 252
Transferring e-mail by way of store-and-forward 253
Transferring e-mail by way of DNS MX records 254
Understanding How SMTP Works with MTAs 255
Defining E-Mail Protocols 255
Adding More Protocols to the Mix 256
POP3 256
IMAP4 257
HTTP 258
LDAP 258
DNS and its MX records 258
TCP/IP For Dummies, 6th Edition xiv
Chapter 14: Securing E-Mail 261
Common Sense: The Most Important Tool in Your Security Arsenal 261
Being Aware of Possible Attacks 262
Phishing 263
Popping up and under 263
Getting spied on 263
Meeting malware 265
Bombing 265
Have you got anything without spam? Spam, spam, spam! 266
Spoofing 267
Finding Out Whether You’re a Victim 267
Playing Hide-and-Seek with Your E-Mail Address 268
Layering Security 269
Layer 1: Letting your ISP protect your network 269
Layer 2: Building your own walls 270
Layer 3: Securing e-mail on the server side 271
Layer 4: Securing e-mail on the client side 274
Layer 5: Suitely extending e-mail security 278
Using Secure Mail Clients and Servers 278
Setting up a secure IMAP or POP client 279
Setting up a secure mail server 281
Encrypting e-mail 281
Chapter 15: Beyond E-Mail: Social Networking and Online Communities 285
Thumbing to Talk About 286
Choosing a Communication Method 287
Getting together with IRC 288
Jabbering with XMPP 288
Feeding Your Craving for News 289
Getting Even More Social 290
Part IV: Even More TCP/IP
Applications and Services 291
Chapter 16: Mobile IP — The Moveable Feast 293
Going Mobile 294
Understanding How Mobile IP Works 294
Sailing into the Future: Potential Mobile IPv6 Enhancements 296
Mobilizing Security 297
Understanding the risks 297
Using basic techniques to protect your mobile devices 298
Table of Contents xv
Chapter 17: Saving Money with VoIP (Voice Over Internet Protocol) 299
Getting the Scoop on VoIP 299
Getting Started Using VoIP 300
Step 1: Get broadband 300
Step 2: Decide how to call 301
Step 3: Make the call 302
Step 4: Convert the bits back into voice (with VoIP software) 303
Step 5: Converse 303
Yo-Yo Dieting: Understanding How VoIP Packets Move through the Layers 304
Trekking the Protocols from RTP to H323 304
Talking the talk with the TCP/IP stack and more 305
Ingesting VoIP standards from the ITU 306
Vomiting and Other Vicious VoIP Vices 306
Securing Your Calls from VoIP Violation 306
You, too, can be a secret agent 307
Authenticating VoIP-ers 307
Keeping voice attacks separate from data 308
Defending with firewalls 308
Testing Your VoIP Security 308
Chapter 18: File and Print Sharing Services 309
Defining Basic File Sharing Terms 309
Using FTP to Copy Files 310
Understanding how FTP works 310
Using anonymous FTP to get good stuff 311
Choosing your FTP client 312
Transferring the files 312
Securing FTP file transfers 315
Using rcp or scp to Copy Files 316
Sharing Network File Systems 317
Nifty file sharing with NFS (Network File System) 317
Solving the buried file update problem with NFSv4 318
Examining the mount Protocol 319
Automounting 320
Configuring an NFS Server 320
Step 1: Edit the exports file 321
Step 2: Update the netgroup file 321
Step 3: Start the daemons 322
Configuring an NFS Client 323
TCP/IP For Dummies, 6th Edition xvi
Picking Up Some NFS Performance Tips 324
Hardware tips 324
Server tips 325
Client tips 325
Weighing performance against security 325
Getting NFS Security Tips 325
Sharing Files Off the Stack 326
Using Windows network shares 326
Using Samba to share file and print services 327
Working with Network Print Services 328
Valuing IPP features 329
Setting up Windows Server 2008 print servers over IPP 330
Printing with the Common Unix Print System (CUPS) 331
Chapter 19: Sharing Compute Power 333
Sharing Network Resources 333
Accessing Remote Computers 334
Using a telnet client 334
“R” you ready for more remote access? 335
Executing commands with rsh and rexec 335
Securing Remote Access Sessions 336
Taking Control of Remote Desktops 337
Sharing Clustered Resources 338
Clustering for high availability 338
Clustering for load balancing 338
Clustering for supercomputing 339
Sharing Compute Power with Grid and Volunteer Computing 339
Part V: Network Troubleshooting and Security 341
Chapter 20: Staying with Security Protocols 343
Determining Who Is Responsible for Network Security 344
Following the Forensic Trail: Examining the Steps for Securing Your Network 344
Step 1: Prescribing Preventive Medicine for Security 345
Step 2: Observing Symptoms of Malware Infection 347
Uncovering more contagions 348
Step 3: Diagnosing Security Ailments with netstat, ps, and Logging 355
Monitoring network use with ps 355
Nosing around with netstat 357
Examining logs for symptoms of disease 362
Syslog-ing into the next generation 363
Microsoft proprietary event logging 370
Table of Contents xvii
Chapter 21: Relishing More Meaty Security 373
Defining Encryption 374
Advancing Encryption with Advanced Encryption Standard (AES) 375
Peering into Authentication 376
Do you have any ID? A digital certificate will do 377
Getting digital certificates 377
Using digital certificates378
Checking your certificates 379
Coping with certificate problems 380
IPSec (IP Security Protocol): More Authentication 381
Kerberos — Guardian or Fiend? 382
Understanding Kerberos concepts 382
Playing at Casino Kerberos 383
Training the dog — one step per head 384
Setting up a Kerberos server step by step 385
Setting up a Kerberos client step by step 387
Chapter 22: Troubleshooting Connectivity and Performance Problems 389
Chasing Network Problems from End to End 390
Getting Started with Ping 390
Pinging away with lots of options 391
And now, for “some-ping” completely different: Running ping graphically 393
Death by ping 395
Diagnosing Problems Step by Step 396
Pinging yourself and others 396
Using nslookup to query a name server 401
Using traceroute (tracert) to fi nd network problems 403
Simplifying SNMP, the Simple Network Management Protocol 406
Just barely describing how SNMP works 406
Using SMNP programming free 407
Part VI: The Part of Tens 411
Chapter 23: Ten More Uses for TCP/IP 413
Chapter 24: Ten More Resources for Information about TCP/IP Security 417
Index 421
