TCP / IP For Dummies

Candace Leiden consults on systems and database performance and instructional design for international courseware. Marshall Wilensky was a consultant and network manager for multiprotocol networks at Harvard University's Graduate School of Business Administration. Both are internationally known speakers.

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