Head First Networking: A Brain-Friendly Guide

Authors of Head First Networking....10

Table of Contents (Summary)....11

Table of Contents (the real thing)....11

Intro....27

Who is this book for?....28

We know what you’re thinking....29

We know what your brain is thinking....29

Metacognition: thinking about thinking....31

Here’s what WE did:....32

Here’s what YOU can do to bendyour brain into submission....33

Read Me....34

The technical review team....36

Acknowledgments....37

Safari® Books Online....38

Chapter 1. Walking on Wires....39

Coconut Airways has a network problem....40

The booking system network cable is busted....42

How do we fix the cable?....43

But how do we do this?....43

Introducing the CAT-5 cable....44

The CAT-5 cable dissected....45

So why are the pairs twisted?....45

So what’s with all the colors?....46

Test Drive....47

Let’s fix the broken CAT-5 cable....49

Where you put each wire is important.....49

A closer look at the RJ-45 connector....50

So which wire goes where?....50

So what are the physical steps?....55

You fixed the CAT-5 cable....57

Coconut Airways has more than one network....58

Introducing the coaxial cable....61

Coaxial networks are bus networks....62

So can we fix the cable?....63

The network’s still not working....64

So what goes on inside a coaxial cable?....66

But what if there’s a break in the conductor?....66

What about connectors and terminators?....67

Use toner-tracer sets to listen to electrons....68

No sound means no electrons....69

So how do we find the continuity break?....69

Cablecross....74

You’ve fixed the coaxial cable....75

Introducing fiber-optic cables....76

Fiber-optics have connectors too....76

The Coconut Airways cable’s over-bent....77

So what’s a fusion splicer?....77

How to fix fiber-optics with afusion splicer....78

A fiber-optic connector needs fitting too....80

We’re nearly ready to fix the connector....82

There are two types of fiber....83

Single mode fiber....83

Multimode fiber....83

Which mode fiber should you use?....84

Let’s fit the connector on the fiber-optic....85

Coconut Airways is sky high....87

Chapter 2. Networking in the Dark....89

Ghost Watch needs your help!....90

Every good network needs a good plan....91

So how does the device list help usplan a network?....92

How to plan a network layout....93

Let’s plan the cabling with a floorplan....94

Ready to plot some network cables?....98

So where have we got to?....101

We need to decide on the cable management hardware....102

Uh oh! The cabling is a mess....103

Ghost Watch needs cable management hardware....104

Things that go bump.......106

You’ve really cleaned up that noise and straightened out MOST of the cables!....111

Let’s start by labeling the cables....112

But there are still lots of cables....113

So what’s a patch panel?....114

Behind the scenes of a patch panel....115

The wires go into a punch down block....116

Roll the cameras!....121

Chapter 3. Into the Wire....123

Mighty Gumball won the Super Bowl contract....124

A toner and tracer can check for a signal.......126

...but can’t check for signal quality....126

Introducing the multimeter....130

Use a multimeter to measure resistance....130

So what’s resistance?....131

When resistance is low....131

When resistance is high....131

So how well did the multimeter do?....137

An oscilloscope shows voltage changes....139

Voltage is really electrical pressure....140

Where does noise on network cables come from?....141

So how well did the oscilloscope perform for Mighty Gumball?....146

A logical analyzer uses voltage too....148

When is a logical analyzer useful?....153

So which tool is best?....153

The Mighty Gumball bonus went to Jill....155

A LAN analyzer combines the functions of all the other tools....156

A LAN analyzer understands thenetwork traffic in the signal....157

So which tool is best?....158

The Mighty Gumball problems are fixed!....161

Chapter 4. You’ve Been Framed....163

What’s the secret message?....164

So how do we extract a message from a signal?....164

Network cards handle encoding....168

So how does the NIC encode the data?....168

To get the message, reverse the encoding....169

So how do we decode the signal?....169

The Ethernet standard tells hardwarehow to encode the data....170

A quick guide to binary....174

So how do we convert a binary to decimal?....174

Computers read numbers, humans read letters....180

But isn’t there an easier way?....180

Hexadecimal to the rescue....182

So how do we convert a hexadecimal to decimal?....182

We can convert to ASCII using hex....183

Back at the spy agency.......190

Protocols define the structure of a message....191

Frames and Packets Up Close....192

Network frames have lots of layers....199

Your friendly packet field guide....200

UDP Packet - Protocol Type 17....200

ICMP Packet - Protocol Type 1....200

TCP Packet - Protocol Type 6....201

So can we decode the secret message?....206

We’ve got all the right packets...but not necessarily in the right order....207

The packet tells you the correct order....208

Networkcross....211

Chapter 5. How Smart is Your Network?....213

You’ve decoded the secret message.......214

...but how do we know who sent it?....214

The packet information tells us where the packet came from....217

So who’s the mole?....218

There’s more to networks than computers....219

Hubs are dumb....220

Hubs don’t change the MAC address....221

So which device sent the packet to the hub?....221

A hub sends signals, and sends them everywhere....222

Hubs think in terms of electricity....222

So what passed the signal to the hub?....223

A switch sends frames, and only sends them where they need to go....224

Switches think in terms of frames....224

Switches are smart....225

Switches store MAC addresses in a lookup table to keep the frames flowing smoothly....226

The switch has the information.......230

We can use software to monitor packets....232

Let’s hook Wireshark up to the switch....233

Wireshark gives us traffic information....234

Routers have MAC addresses too....237

Network ports Routers are really smart....238

We’re closing in!....239

You’ve found the mole!....241

Chapter 6. Bringing Things Together....243

Networking on the moon....244

We need to connect two networks together....247

The light’s on, but nobody’s home....248

What do you think the flashing LEDs have to do with traffic on the network?....248

Let’s see what traffic is on our network!....250

MAC address versus IP address....252

IP addresses give our networks a sense of location, and network nodes a sense of belonging to that location....253

We retrieve IP addresses using the MAC address and the Address Resolution Protocol (ARP)....254

So what’s the problem with the Moonbase?....259

How do we get network traffic to move between networks?....260

How the router moves data across networks....262

Back to the Moonbase problem....264

The secret of IP numbers is.......265

Routers connect networks by doing the math.......266

The Router Exposed....269

Back at the Moonbase.......273

Are you ready to program the router?....274

You just created this router config file!....276

Let the router tell us what’s wrong.......278

Chapter 7. It’s a Matter of Protocol....281

Houston, we have a problem.......282

Routing tables tell routers where to send packets....283

We can see routes in the table using the show command....283

Each line represents a different route....284

So how do we enter routes?....286

Routes help routers figure out where to send network traffic....287

So are the moonbases now connected?....291

Back on the moon.......293

So how do we troubleshoot bad routes?....294

We can start with the ping command....294

The traceroute command is useful too....295

So what’s the problem with the network connection?....299

The network address changes keepon coming.......300

Use RIP to get routes to update themselves....302

So what does this mean for Moonbase 1?....303

So how do we set up RIP?....308

But there’s still a problem.......309

There are too many hops....310

RIP can only use the hop count to find the best route.....310

There are other routing protocols.....313

The routing protocol zoo....314

EIGRP Up Close....318

EIGRP uses the Diffusing Update Algorithm....319

EIGRP uses the Reliable Transport Protocol to send its information....319

EIGRP only sends route updates when there are changes....319

So how do we setup EIGRP?....320

We have lift off!....326

Chapter 8. Names to Numbers....329

The Head First Health Club needs a website....330

Hello, my domain name is.......331

So how do we get a domain name?....331

Let’s go buy a domain name....332

Uh-oh! We’re in trouble....334

And she’s not the only one....334

Introducing the DNS....336

The DNS relies on name servers....336

How the DNS sees your domain....337

So how does this affect the Health Club?....342

First install a DNS name server.......344

...then configure the name server....345

The Nameserver Exposed....351

The anatomy of a DNS zone file....352

Here’s what the DNS zone file tells us about the Health Club servers....353

Name Servers....353

Mail Server....353

Other Servers....353

The Health Club can’t send emails....355

So what’s the problem?....356

Email servers use RDNS to fight SPAM....356

Check your sources with reverse DNS....357

The dig command can do a reverse DNS lookup....358

Your name server has another important zone file.......360

The emails are working!....365

Chapter 9. Listen to Your Network's Troubles....367

Pajama Death are back on tour....368

So here’s your challenge.......368

So where would you start troubleshooting a misfiring network?....369

Start troubleshooting your network problems by checking in with your network devices....371

Troubleshoot network connectivity with the ping command....372

If you can ping, you get timings....372

But what if you can’t ping?....372

If the ping fails, check the cables....373

Get started with the show interface command....379

The interface’s network statistics are a goldmine of troubleshooting information....379

Cisco Show Command Exposed....380

The ticket network’s still not fixed....383

How can we quickly troubleshoot networks without SSH or telnet?....383

SNMP to the rescue!....384

SNMP is a network admininistrator’s communication tool....385

SNMP does allow some access control....385

How to configure SNMP on a Cisco device....386

One hour to go.......391

SNMP gets most of the information, but not all of it.....391

Get devices to send you their problems....392

How to configure syslogd on a Cisco device....393

How do you tell what’s in the logs?....394

syslogd lets you fix problems before they’re problems....394

Too much information can be just as bad as not enough....397

What you need is relevant information....397

How do you know which events are important?....398

Pajama Death’s a sell-out!....399

Chapter 10. Working Without Wires....401

Your new gig at Starbuzz Coffee....402

Starbuzz Coffee needs a wireless hotspot....402

Wireless access points create networks using radio waves....403

Let’s fit the wireless access point....404

What about the network configuration?....411

Maybe she has a point.....411

So what’s DHCP?....412

DHCP allocates IP addresses....413

First make sure the client has DHCP turned on.......414

Second, make the wireless access point a DHCP server.......414

...and then specify an acceptable range of IP addresses....415

The DHCP Server Exposed....416

So has setting up DHCP solved the problem?....416

This time it’s personal....417

We’ve run out of IP addresses....418

We can get around the IP address problem by implementing NAT.....418

NAT works by reallocating IP addresses....419

So how do we configure NAT?....420

So has this fixed the problem?....423

There’s more than one wireless protocol....424

Most newer access point support multiple protocols....424

The central Starbuzz server needs to access the cash register....428

Port mapping to the rescue!....430

So port mapping is a bit like NAT in reverse....431

Let’s set up port mapping on the Starbuzz access point....432

Wireless Security Up Close....435

The wireless access point is a success!....436

Chapter 11. Get Defensive....437

The bad guys are everywhere....438

And it’s not just the NETWORK that gets hurt.......439

The big four in network security....440

Defend your network against MAC address spoofing....443

So how do we defend against MAC address spoofing?....448

Defend your network against ARP poisoning attacks....449

So what can we do about ARP poisoning attacks?....450

It’s all about the access, baby!....452

If an attacker can get past your router, then he’s on your network!....452

Set up your router’s Access Control Lists to keep attackers out....453

So how do we configure the Access Control List?....455

Firewalls filter packets between networks....458

Packet-filtering rules!....459

Get smart with stateful packet-filters....464

Master the static packet filter....460

Humans are the weakest link in your security chain....467

So how do social engineers operate?....468

Smash social engineering with a clear and concise security policy....470

You’ve hardened your network....473

Chapter 12. You Gotta Have a Plan!....475

Now you have to plan a network from scratch!....476

You have to know what the needs are before you can plan....479

So you’ve developed your questions, now what?....481

Look at your action plan....482

So you have a physical layout, what’s next?....485

Blueprints show everything in a building’s design....486

You may have to modify your network design based on what you see in the blueprints!....487

So you’ve got your physical network layout, what’s next?....494

You have got several options to segment this into two networks....497

Finally, you need an implementation plan....502

Congratulations, you’ve designed an awesome network from scratch.....505

It’s been great having you here in Networkville!....506

appendix i: leftovers....507

#1 Network topologies....508

Star topology....508

Bus topology....509

Token Ring topology....509

#2 Installing Wireshark....510

Windows Install....510

Mac OS X Install....511

Linux Install (Ubuntu)....511

#3 How to get to the console or terminal....512

Windows....512

Linux....512

Mac OS X....512

#4 The TCP Stack....513

#5 VLANS....514

#6 Cisco IOS Simulators....514

#7 BGP....515

#8 VPN....515

#9 Intrusion Detection Systems....516

#10 Cisco Certification....516

appendix ii: ascii tables....517

ASCII tables 0-31....518

ASCII code tables 32-63....519

ASCII code tables 64-95....520

ASCII code tables 96-127....521

appendix iii: installing bind....523

#1 Installing BIND on Windows (XP, 2000, Vista)....524

#2 Installing BIND Mac OS X Server....525

#3 Installing BIND Mac OS X Client & Linux....525

Index....527

Numbers....527

A....527

B....527

C....527

D....528

E....529

F....529

G....530

H....530

I....531

J....531

L....531

M....531

N....532

O....533

P....533

R....534

S....535

T....536

U....537

V....537

W....537

Frustrated with networking books so chock-full of acronyms that your brain goes into sleep mode? Head First Networking's unique, visually rich format provides a task-based approach to computer networking that makes it easy to get your brain engaged. You'll learn the concepts by tying them to on-the-job tasks, blending practice and theory in a way that only Head First can.With this book, you'll learn skills through a variety of genuine scenarios, from fixing a malfunctioning office network to planning a network for a high-technology haunted house. You'll learn exactly what you need to know, rather than a laundry list of acronyms and diagrams. 

This book will help you:

• Master the functionality, protocols, and packets that make up real-world networking
• Learn networking concepts through examples in the field
• Tackle tasks such as planning and diagramming networks, running cables, and configuring network devices such as routers and switches
• Monitor networks for performance and problems, and learn troubleshooting techniques
• Practice what you've learned with nearly one hundred exercises, questions, sample problems, and projects

Head First's popular format is proven to stimulate learning and retention by engaging you with images, puzzles, stories, and more. Whether you're a network professional with a CCNA/CCNP or a student taking your first college networking course, Head First Networking will help you become a network guru.