Head First Networking. A Brain-Friendly Guide

Spis treści książki

• Head First Networking
• Dedication
• Advance Praise for Head First Networking
• Praise for other Head First books
• Authors of Head First Networking
• How to Use this Book: Intro
  • Who is this book for?
    • Who should probably back away from this book?
  • We know what youre thinking
  • We know what your brain is thinking
  • Metacognition: thinking about thinking
  • Heres what WE did:
  • Heres what YOU can do to bend your brain into submission
  • Read Me
  • The technical review team
  • Acknowledgments
  • Safari Books Online
• 1. Fixing Physical Networks: Walking on Wires
  • Coconut Airways has a network problem
    • The booking system network cable is busted
  • How do we fix the cable?
    • But how do we do this?
  • Introducing the CAT-5 cable
  • The CAT-5 cable dissected
    • So why are the pairs twisted?
  • So whats with all the colors?
  • Lets fix the broken CAT-5 cable
  • A closer look at the RJ-45 connector
    • So which wire goes where?
  • So what are the physical steps?
  • You fixed the CAT-5 cable
  • Coconut Airways has more than one network
  • Introducing the coaxial cable
  • Coaxial networks are bus networks
  • So can we fix the cable?
  • The networks still not working
  • So what goes on inside a coaxial cable?
    • But what if theres a break in the conductor?
  • What about connectors and terminators?
  • Use toner-tracer sets to listen to electrons
  • No sound means no electrons
    • So how do we find the continuity break?
  • Youve fixed the coaxial cable
  • Introducing fiber-optic cables
    • Fiber-optics have connectors too
  • The Coconut Airways cables over-bent
    • So whats a fusion splicer?
  • How to fix fiber-optics with a fusion splicer
  • A fiber-optic connector needs fitting too
  • Were nearly ready to fix the connector
  • There are two types of fiber
    • Single mode fiber
    • Multimode fiber
  • Which mode fiber should you use?
  • Lets fit the connector on the fiber-optic
    • So which technique should we use?
  • Coconut Airways is sky high
• 2. Planning Network Layouts: Networking in the Dark
  • Ghost Watch needs your help!
  • Every good network needs a good plan
  • So how does the device list help us plan a network?
  • How to plan a network layout
  • Lets plan the cabling with a floorplan
  • Ready to plot some network cables?
  • So where have we got to?
  • We need to decide on the cable management hardware
  • Uh oh! The cabling is a mess
  • Ghost Watch needs cable management hardware
  • Things that go bump...
  • Youve really cleaned up that noise and straightened out MOST of the cables!
    • Whats in the closet?
  • Lets start by labeling the cables
  • But there are still lots of cables
    • But what else can we do?
  • So whats a patch panel?
  • Behind the scenes of a patch panel
  • The wires go into a punch down block
  • Roll the cameras!
• 3. Tools and Troubleshooting: Into the Wire
  • Mighty Gumball won the Super Bowl contract
  • A toner and tracer can check for a signal...
  • ... but cant check for signal quality
  • Introducing the multimeter
    • Use a multimeter to measure resistance
  • So whats resistance?
    • When resistance is low
    • When resistance is high
  • So how well did the multimeter do?
  • An oscilloscope shows voltage changes
  • Voltage is really electrical pressure
    • So how does this help us troubleshoot problems?
  • Where does noise on network cables come from?
  • So how well did the oscilloscope perform for Mighty Gumball?
  • A logical analyzer uses voltage too
  • When is a logical analyzer useful?
  • So which tool is best?
  • The Mighty Gumball bonus went to Jill
  • A LAN analyzer combines the functions of all the other tools
  • A LAN analyzer understands the network traffic in the signal
  • So which tool is best?
  • The Mighty Gumball problems are fixed!
• 4. Packet Analysis: Youve Been Framed
  • Whats the secret message?
    • So how do we extract a message from a signal?
  • Network cards handle encoding
    • So how does the NIC encode the data?
  • To get the message, reverse the encoding
    • So how do we decode the signal?
  • The Ethernet standard tells hardware how to encode the data
  • A quick guide to binary
    • So how do we convert a binary to decimal?
  • Computers read numbers, humans read letters
    • But isnt there an easier way?
  • Hexadecimal to the rescue
    • So how do we convert a hexadecimal to decimal?
  • We can convert to ASCII using hex
  • Back at the spy agency...
  • Protocols define the structure of a message
  • Network frames have lots of layers
  • Your friendly packet field guide
    • UDP Packet - Protocol Type 17
    • ICMP Packet - Protocol Type 1
    • TCP Packet - Protocol Type 6
  • So can we decode the secret message?
  • Weve got all the right packets... but not necessarily in the right order
  • The packet tells you the correct order
• 5. Network Devices and Traffic: How Smart is Your Network?
  • Youve decoded the secret message...
    • ...but how do we know who sent it?
  • The packet information tells us where the packet came from
  • So whos the mole?
  • Theres more to networks than computers
  • Hubs dont change the MAC address
    • So which device sent the packet to the hub?
  • A hub sends signals, and sends them everywhere
    • Hubs think in terms of electricity
  • So what passed the signal to the hub?
  • A switch sends frames, and only sends them where they need to go
    • Switches think in terms of frames
  • Switches store MAC addresses in a lookup table to keep the frames flowing smoothly
  • The switch has the information...
  • We can use software to monitor packets
  • Lets hook Wireshark up to the switch
  • Wireshark gives us traffic information
  • Routers have MAC addresses too
  • Were closing in!
  • Youve found the mole!
• 6. Connecting Networks with Routers: Bringing Things Together
  • Networking Walking on the moon
  • We need to connect two networks together
  • The lights on, but nobodys home
    • What do you think the flashing LEDs have to do with traffic on the network?
  • Lets see what traffic is on our network!
  • MAC address versus IP address
  • IP addresses give our networks a sense of location, and network nodes a sense of belonging to that location
  • We retrieve IP addresses using the MAC address and the Address Resolution Protocol (ARP)
  • So whats the problem with the Moonbase?
  • How do we get network traffic to move between networks?
  • How the router moves data across networks
  • Back to the Moonbase problem
  • The secret of IP numbers is...
  • Routers connect networks by doing the math...
  • Back at the Moonbase...
  • Are you ready to program the router?
  • You just created this router config file!
  • Let the router tell us whats wrong...
• 7. Routing Protocols: Its a Matter of Protocol
  • Houston, we have a problem...
  • Routing tables tell routers where to send packets
    • We can see routes in the table using the show command
  • Each line represents a different route
  • So how do we enter routes?
  • Routes help routers figure out where to send network traffic
  • So are the moonbases now connected?
  • Back on the moon...
    • Moonbase 1 still has problems
  • So how do we troubleshoot bad routes?
    • We can start with the ping command
    • So how does the ping command work?
  • The traceroute command is useful too
  • So whats the problem with the network connection?
  • The network address changes keep on coming...
  • Use RIP to get routes to update themselves
    • So what does this mean for Moonbase 1?
  • So how do we set up RIP?
  • But theres still a problem...
  • There are too many hops
  • The routing protocol zoo
  • So how do we setup EIGRP?
  • We have lift off!
• 8. The Domain Name System: Names to Numbers
  • The Head First Health Club needs a website
  • Hello, my domain name is...
    • So how do we get a domain name?
  • Lets go buy a domain name
  • Uh-oh! Were in trouble
    • And shes not the only one
  • Introducing the DNS
  • The DNS relies on name servers
  • How the DNS sees your domain
  • So how does this affect the Health Club?
  • First install a DNS name server...
  • ...then configure the name server
  • The anatomy of a DNS zone file
  • Heres what the DNS zone file tells us about the Health Club servers
  • The Health Club cant send emails
  • So whats the problem?
  • Email servers use RDNS to fight SPAM
  • Check your sources with reverse DNS
  • The dig command can do a reverse DNS lookup
  • Your name server has another important zone file...
  • The emails are working!
• 9. Monitoring and Troubleshooting: Listen to Your Networks Troubles
  • Pajama Death are back on tour
    • So heres your challenge...
  • So where would you start troubleshooting a misfiring network?
  • Start troubleshooting your network problems by checking in with your network devices
  • Troubleshoot network connectivity with the ping command
    • If you can ping, you get timings
    • But what if you cant ping?
  • If the ping fails, check the cables
  • Get started with the show interface command
    • The interfaces network statistics are a gold mine of troubleshooting information
  • The ticket networks still not fixed
  • SNMP to the rescue!
  • SNMP is a network admininistrators communication tool
  • How to configure SNMP on a Cisco device
  • One hour to go...
  • Get devices to send you their problems
  • How to configure syslogd on a Cisco device
  • How do you tell whats in the logs?
    • syslogd lets you fix problems before theyre problems
  • Too much information can be just as bad as not enough
    • What you need is relevant information
  • How do you know which events are important?
  • Pajama Deaths a sell-out!
• 10. Wireless Networking: Working Without Wires
  • Your new gig at Starbuzz Coffee
    • Starbuzz Coffee needs a wireless hotspot
  • Wireless access points create networks using radio waves
  • Lets fit the wireless access point
  • What about the network configuration?
  • So whats DHCP?
    • DHCP allocates IP addresses
  • First make sure the client has DHCP turned on...
  • Second, make the wireless access point a DHCP server...
  • ...and then specify an acceptable range of IP addresses
  • So has setting up DHCP solved the problem?
  • This time its personal
  • Weve run out of IP addresses
  • NAT works by reallocating IP addresses
  • So how do we configure NAT?
  • So has this fixed the problem?
  • Theres more than one wireless protocol
    • Most newer access point support multiple protocols
    • So is the Starbuzz wireless access point sorted?
  • The central Starbuzz server needs to access the cash register
  • Port mapping to the rescue!
    • So port mapping is a bit like NAT in reverse
  • Lets set up port mapping on the Starbuzz access point
  • The wireless access point is a success!
• 11. Network Security: Get Defensive
  • The bad guys are everywhere
    • The evil impersonator
    • The evil attacker
  • And its not just the NETWORK that gets hurt...
    • The evil eavesdropper
  • The big four in network security
  • Defend your network against MAC address spoofing
  • So how do we defend against MAC address spoofing?
  • Defend your network against ARP poisoning attacks
  • So what can we do about ARP poisoning attacks?
  • Its all about the access, baby!
    • If an attacker can get past your router, then hes on your network!
  • Set up your routers Access Control Lists to keep attackers out
  • So how do we configure the Access Control List?
  • Firewalls filter packets between networks
  • Packet-filtering rules!
  • Master the static packet filter
  • Get smart with stateful packet-filters
  • Humans are the weakest link in your security chain
  • So how do social engineers operate?
  • Smash social engineering with a clear and concise security policy
  • Youve hardened your network
• 12. Designing Networks: You Gotta Have a Plan!
  • Now you have to plan a network from scratch!
  • You have to know what the needs are before you can plan
  • So youve developed your questions, now what?
  • Look at your action plan
  • So you have a physical layout, whats next?
  • Blueprints show everything in a buildings design
  • You may have to modify your network design based on what you see in the blueprints!
  • So youve got your physical network layout, whats next?
    • You have got several options to segment this into two networks
  • Finally, you need an implementation plan
  • Leaving town...
  • Its been great having you here in Networkville!
• A. Leftovers: The Top Ten Things (we didnt cover)
  • #1 Network topologies
    • Star topology
    • Bus topology
    • Token Ring topology
  • #2 Installing Wireshark
    • Windows Install
    • Mac OS X Install
    • Linux Install (Ubuntu)
  • #3 How to get to the console or terminal
    • Windows
    • Linux
    • Mac OS X
  • #4 The TCP Stack
  • #5 VLANS
  • #6 Cisco IOS Simulators
  • #7 BGP
  • #8 VPN
  • #9 Intrusion Detection Systems
  • #10 Cisco Certification
• B. Ascii Tables: Looking Things Up
  • ASCII tables 0-31
  • ASCII code tables 32-63
  • ASCII code tables 64-95
  • ASCII code tables 96-127
• C. Installing Bind: Getting a Server to talk DNS
  • #1 Installing BIND on Windows (XP, 2000, Vista)
  • #2 Installing BIND Mac OS X Server
  • #3 Installing BIND Mac OS X Client & Linux
• Index
• About the Authors
• Copyright

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