Linux Networking-Concepts HOWTO
Rusty Russell
$ Revision: 1.13 $ $ DATE: 2001/07/29 04:45:11 $
This Document Describes What a network (Such as the Internet) IS, AND
The Very Basics Of How IT Works.
___________________________________________________________
Table of contents
INTRODUCTION
2. What is a `computer network '?
3. What is the `Internet '?
3.1 How does The Internet Work?
4. This IP Thing
4.1 Groups of IP Addresses: Network Masks
5. Machine Names and IP Addresses
6. Different Services: Email, Web, FTP, Name Serving
7. Dialup Interfaces: PPP
8. What Packets Look Like
9. Summary
10. THANKS
11. INDEX
___________________________________________________________
[1M1. Introduction [0M
Welcome, Gentle Reader.
I Have Written a Number of Networking HOWTOS in the Past, And IT
Occurred to me That there's a hell of pile of jargon in each one. i
Had Three Choices: My Other Two Were Ignoring The Problem and
EXPLAINING The Terms Evewhere. Neither Was Attractive.
The [1 Mpoint [22Mof Free Software Is this you shop "freedom to
Explore and play with the software systems you use. I believe That
ENABLING People to Experience this freedom is a NobLes Goal; Not ONLY
Do People Feel Empowered by The Pursuit (Such As Rebuilding A Car
Engine) But The Nature of the Modern Internet and Free Software Allows
You to Share the experience with millions.
But you have to start somewhere, so here we are.
(C) 2000 Paul `Rusty 'Russell. Licenced Under The GNU GPL.
[1M2. What is a `computer network '? [0M
A Computer Network Is Just A Set of Stuff for Nodes To Talk to Each
Other (by `Nodes' I Mean Computers, Printers, Coke Machines)
Whatver else you want). It doesn't really matter [1MHOW [22Mthey Areconnected: The Could Use Fiber-Optic Cables Or Carrier Pigens.
Obviously, Some Choices Are Better Than Others (especially if you have
a cat).
USUALLY INTER, IT'S NOT CALLED A
NetWork; you really nesed three or more to become a network. this is a
Bit Like the Word `Group ': Two people is just a couple of guys, but
Three Can Be An `Group '. Also, Networks Are Offen Hooked Together, TO
Make Bigger NetWorks; Each Little Network (Usually Called A `Sub-
Network ') Can Be Part of a Larger Network.
The Actual Connection Between Two Computers Is Offen Called A `Network
Link '. if There's a bit of cable running out of the background of your your
Machine to the Other Machines, That's your network link.
There Are Four Things Which We Usually Care About When We Talk About A
Computer Network:
[1MSIZE [0M
IF you simply connect your four computers at home together, you
Have What Is Called A LAN (Local Area Network). if everything
Is With Walking Distance, It's Usually Called A LAN, HOWEVER
Many Machines Are Connected to It, And Whatever You'VE Built The BUILT THE
NetWork out of.
The Other End of The Spectrum IS A WAN (Wide Area Network). If
You Have ONE COMPUTER in Lahore, Pakistan, One in Birmingham, UK
And One in Santiago, Chile, And You Manage to Connect Them, It's
A WAN.
[1Mtopology: The Shape [0M
Draw a Map of the Network: LINES Are T
`` network links '', And each node is a dot. Maybe each line
Leads Into a Central Node Like A Big Star, Meaning That Everyone
Talks Through One Point (a `Star Topology '):
O O O
/ _ | _ /
/ | /
o ----- O ----- O_ / | / _
/ | /
O O O
Maybe Eveyone Talks in a line, Like SO:
o ------ O ------ O ------- O -------- O
| | |
| | |
| o
| | |
O |
o
Or Maybe You Have Three SubnetWorks Connected THROUGH ONE NODE:
o
O | O - O - O
| | | | |
O - O - O O O
/ |
o ------ O
/ |
O - O - O O O
| | | | |
o | o - o
o
You'll See Many Topologies Like There in Real Life, And Many Far
More complicated.
[1 Mphysical: What It's Made of [0M
The Second Thing to Care About Is What You've Built The Network
Out of. The cheapest is `sneakernet ', where badly-dressed
People Carry Floppy Disks from One Machine to The Others.
Sneakernet is Almost Always A `` Lan ''. Floppies Cost Less Than
$ 1, And A Solid Pair of Sneakers Can Be Got for Around $ 20.
The Most Common System Used to Connect Home Networks To FAR
Bigger Networks Is Called A `MODEM '(for modulator / demodulator),
Which Turns A Normal Phone Connection Into a Network Link. IT
Turns The Stuff The Computer Sends Into Sounds, And Listens To
Sounds coming from the other other end to turn the back Into stuff
For the Computer. as you can images, this isn't Very
Efficient, And Phone Lines beceple Designed for this use, but BUT
IT's Popular Because Phone Lines Are So Common and Cheap: MODEMS
Sell for Less Than $ 50, And Phone Lines Usually Cost A Couple of
Hundred Dollars a year.
The Most Common Way to Connect Machines Into a Lan Is To Use
Ethernet. Ethernet comes in these main flavors (listed from
Oldest to newest): Thinwire / COAX / 10BASE2, UTP (unshieldTwisted Pair) / 10Baset and Utp / 100Baset. Gigabit Ethernet (The
Name 1000Baset Is Starting to Get Silly) Is Starting To BE
Deployed, Too. 10Base2 Wire Is Usually Black Coaxial Cable,
WITH TWIT-ON T-PIECES To Connect Them To Things: Everyone Gets
Connected in a big line, with special `Terminator 'Pieces on The
Two ends. UTP is Usually Blue Wire, with clear `click-in '
Phone-Style Connectors Which Plug Into Sockets to Connect: EACH
Wire Connects One Node to a Central `Hub '. The Cable IS A
Couple of Dollars a meter, and the 10baset / 10Base2 Cards (Many
Cards Have Plugs for Both) Are Hard To Get Brand New. 100BaseT
Cards, Which Can Also Speak 10baset As Well, Are Ten Times
Faster, And About $ 30.
ON The Other End of The Spectrum is Fiber; a Continuous Tiny
Glass Filament Wrapped in Protective Coating Which Can Be Used
To Run Between Continents. General, Fiber Costs Thousands.
WE USUALLY CALL EACH Connection to a node a `network interface ',
OR `Interface 'for short. Linux gives these names like` eth0'
For The First Ethernet Interface, and `fddi0 'for the first
Fiber Interface. The `/ sbin / ifconfig 'Command Lists Them.
[1MPROTOCOL: What It's Speaking [0M
The Final Thing to Care About Is The Language The TWO ARE
Speaking. When Two `` Modems '' Are Talking to Each Other Down A
Phone Line, They Need To Agree What The Different Sounds Mean,
OtherWise IT Simply Won't work. This Convention is Called A
`protocol '. as people discovered new ways of encoding what
Computer Says Into Smaller Sounds, New Protocols Were Invented
There Are AT Least A Dozen Different Modem Protocols, And Mostmodems Will Try A Number of Them Until The Find One The Other
End Understands.
Another Example Is The `` 100baset '' NetWork Mentioned Above: IT
Uses the Same Physical `` NetWork Links' '(`` uTP') AS
`` 10baset '' Above, But Talks Ten Times as fast.
There Two Protocols Are What Are Called `Link-Level 'Protocols;
How stuff is handed over the individual network links, or `one
Hop '. The word `protocol' Also Refers To Other Conventions
Which is Followed, As We Will See Next.
[1M3. What is the `Internet '? [0M
The Internet is a `` wan '' Which Spans The Entire Globe: It is the
Largest Computer Network in Existence. The Phrase `Internetworking '
Refers to Connecting Separate Networks to build a larder one, hence
`The Internet 'is The Connection of A Whole Pile of SubnetWs.
SO NOW WE LOOK AT THE LIST ABOVE and Ask Ourslves: What is the
Internet's Size, Physical Details and protocolls?
The size is already Established Above: It's global.
The Physical Details Are Varied However: Each Little Sub-Network IS
Connected DiffERENTLY, WITH A DIFFERENT LAYOUT AND Physical Nature.
Attempts to map it in a useful way home generally met with Abject
Failure.
The Protocols Spokeen by Each Link Are Also Offerent: All of the
`` link-level protocoll '' 'listed above area.ed, and man more.
[1M3.1. How does the internet work? [0M
The Question Then Arises: How Come Every Node on The Internet Can Talk
To the Others, if The All Use Different Link-Level Protocols To Talk
TO Each other?
THE ANSWER IS FAIRLY SIMPLE: WE NEED Another Protocol Which ControlShow Stuff Flows Through The Network. The link-level protocol
Describes How To Get from One Node To Another If They're Connected
Directly: The `network protocol 'tells us how to get from One Point in
The network to any other, going through other links if Necessary.
For the Internet, The Network Protocol Is The Internet Protocol
(Version 4), OR `IP '. It's not the only protocol out there (Apple's
AppleTalk, Novell's IPX, Digital's Decnet and Microsoft's NetBeui
Being Others) But it's the MOST WIDELY Adopted. There's A NEWER
Version of IP Called IPv6, But It's Still Not Common.
So to send a message from one side of the globe to another, your
Computer Writes A Bit of Internet Protocol, Sends It To your Modem,
Which Uses Some Modem Link-Level Protocol To send it to the modem it's
Daialed Up to, Which is probably plugged Into a Terminal Server
(Basically a big box of modems), Which Sends it to a node inside
ISP's NetWork, Which Sends It out USUALLY TO A BIGGER Node, Which
Sends it to the next node ... and so on. a Node Which Connects Two OR
More networks is caled a `Router ': it will have one` `interface'?
Each network.
We call this Array of Protocols a `protocol stack ', Usually Drawn Like
SO:
[Application: Handles Porn] [Application Layer: SERVES PORN]
| ^
V |
[TCP: Handles Retransmission] [TCP: HANDLES RETRANSMISSION]
| ^
V |
[IP: Handles Routing] [IP: HANDLES ROUTING] | ^
V |
[Link: handles a single hop] [link: handles a single hop]
| | |
----------------------------------------
So in the diagram, We See Netscape (The Application On TOP LEFT)
Retrieving a Web Page from A Web Server (The Application On TOP
Right). To do this it will use `Transmission Control Protocol 'OR
`TCP ': Over 90% of The Internet Traffic Today IS TCP, AS IS Used
For web and email.
SO Netscape Makes The Request for a TCP Connection To The Remote Web
Server: this is handed to the TCP LAYER, Which Hands it to the ip
Layer, Which Figures Out Which Direction It Has To Go in, Hands IT
Onto the appropriate Link Layer, Which Transmits It to the Other End
Of the link.
At the other end, the link layer hands it up to the ip layer, which
SEES IT IS Destined for this Host (if not, IT Might Hand It Down TO A
Different Link Layer To Go Out to the next node, Hands it up to the
TCP Layer, Which Hands It To The Server.
So We since the Following Breakdown:
1. The Application (Netscape, or the Web Server At the Other End)
Decides Who It Wants To Talk To, and what it wants to send.
2. The TCP LAYER Sends Special Packets To Start The Conversation with
The other end, and then packs the data into a tcp `packet ': a
Packet Is Just A Term for a Chunk of Data Which Passes Through A
Network. The TCP Layer Hands this Packet To
THE IP LAYER: IT THEN Keeps Sending It to the ip Layer Until The
TCP Layer At The Other End Replies To Say That It Has Received IT.
This Is Called `Retransmission ', And Has A Whole Heap of ComplexRules Which Control When To Retransmit, How long To Wait, ETC. IT
Also Gives Each Packet A Set of Numbers, Which Mean That The other
End can Sort The Into The Right ORDER.
3. The IP Layer Looks At the Destination of the Packet, and Figure
Out the next node to send the packet to. this Simple Act Is Called
`routing ', and Ranges from really simple (if you only", i i 中
Modem, And no Other Network Interfaces, All Packets Should Go Out
That interface) to Extremely Complex (if you have 15 Major Networks
Connected Directly to you).
[1M4. This ip thing [0M
So the role of the ip layer is to Figure outhow to `route 'packets to
THEIR Final Destination. To make this Possible, Every Interface ON
The Network Needs An `ip address'. An IP Address Consists of Four
Numbers Separated by Periods, Like `167.216.245.249 '. Each Number IS
Between Zero and 255.
Interfaces in The Same Network Tend to Have Neighboring IP Addresses.
For example, `167.216.245.250 'Sits Right Next to the machine with the
IP Address `167.216.245.249 '. Remember Also That A Router is a node
With interfaces on more Than One Network, So The Router Will Have ONE
IP Address for Each Interface.
SO The Linux Kernel's IP Layer Keeps a Table of Different `routes',
Describing How To Get To Various Groups of IP Addresses. The SimpleSt
Of these is caled a `default route ': if The ip layer doesn't know
Better, this is where it will send a packet onwards to. You can see a
List of routes use `/ sbin / route '.
Routes Can Either Point To a Link, or a Particular Node Which IS
Connected to Another Network. for Example, When You Dial Up to Theisp, Your Default Route Will Point To The Modem Link, Because That's
WHERE The entire world is.
Rusty's ISP's ~~~~~~~~~~~~
Modem modem {}
o ------------------ o {the internet}
{}
~~~~~~~~~~~~
But if you have a permanent machine on your network Which connection
The outside world, it's a bit more complicated. in the diagram below,
My Machine Can Talk Directly to Tridge and Paul's Machines, and to the
Firewall, But it Needs to know That Packets Heading the rest of the
World need to go to the firewall, Which Will Pass Them on. This means
That you have two routes: One Which Says `IF It's on My Network, JUST
Send it straight there 'and then a default route Which Says
`OtherWise, Send it to firewall '.
o Tridge's
| Work Machine ~~~~~~~~~~~~
Rusty's | {}
Work Machine O -------- ----------------- O - {the Internet}
| Firewall {}
| ~~~~~~~~~~~~
o Paul's
Work Machine
[1M4.1. Groups of IP Addresses: Network masks [0M
There is one last detail: There Is A Standard Notation for Groups of GROUPS OF
IP Addresses, Sometimes Called A `Network Address'. Just Like A Phone
Number Can Be Broken Up Into An Area Prefix and The Rest, We CAN
Divide an ip address INTO A NetWork Prefix and The REST.
IT Used to Be That People Would Talk About `The 1.2.3 network ',
Meaning All 256 Addresses from 1.2.3.0 to 1.2.3.255. Or if That
Wasn't a big enough network, They might talk about the `1.2 network '
Which Meant All Addresses from 1.2.0.0 to 1.2.255.255.we us usually don't write `1.2.0.0 - 1.2.255.255 '. INSTEAD, We Shorten
IT TO `1.2.0.0/16 '. THIS Weird` / 16' Notation (It's Called A
`Netmask ') Requires a little explanation.
Each Number Between The Dots in An IP Address Is Actually 8 Binary
Digits (00000000 to 1111111): WE WRITE THEM in Decimal Form To Make
IT More Readable for Humans. THE `/ 16 'Means That The First 16 Binary
Digits is the network address, in other words, the `1.2. 'part is the
The NetWork (Remember: Each Digit Repensents 8 Binary Digits). THIS
Means Any IP Address Beginning with `1.2. 'Is Part of The Network:
`1.2.3.4 'and` 1.2.3.50' Are, and `1.3.1.1 'is not.
To make life easier, we usually use networks ending in `/ 8 ',` / 16' and
`/ 24 '. For example,` 10.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.00 #
Address from 10.0.0.0 to 10.255.255.255 (Over 16 Million Addresses!).
10.0.0.0/16 Is Smaller, Containing Only IP Addresses from 10.0.0.0 TO
10.0.255.255. 10.0.0.0/24 Is Smaller Still, Containing Addresses
10.0.0.0 to 10.0.0.0.255.
To make things confusing, There is another warfusing.
We can Write Them Like IP Addresses:
10.0.0.0/255.0.0.0
Finally, It's Worth Noting That The Very Highest IP Address in Any
Network is reserved as the `Broadcast Address', Which Can Be Used To
Send a message to everyone on the network at.
Here is a Table of Network Masks:
Short Full Maximum Comment
Form form # machines
/ 8 / 255.0.0.0 16,777,215 used to be called an `a-class'
/ 16 / 255.255.0.0 65,535 Used to be caled an `b-class' / 17 / 255.255.128.0 32,767
/ 18 / 255.255.192.0 16,383
/ 19 / 255.255.224.0 8,191
/ 20 / 255.255.240.0 4,095
/ 21 / 255.255.248.0 2,047
/ 22 / 255.255.252.0 1,023
/ 23 / 255.255.254.0 511
/ 24 / 255.255.255.0 255 used to be caled a `c-class'
/ 25 / 255.255.255.128 127
/ 26 / 255.255.255.192 63
/ 27 / 255.255.255.224 31
/ 28 / 255.255.255.240 15
/ 29 / 255.255.255.248 7
/ 30 / 255.255.255.252 3
[1M5. Machine Names and IP Addresses [0M
So Every Interface On Every Node Has An IP Address. It was realized. IT WAS REALIZED
Quite Quickly That Humans Are Pretty Bad At Remembering Numbers, SO IT
WAS Decid (Just Like Phone Numbers) to have a directory of name.
But Since We're Using Computers Anyway, It's Nic To Have The
Computer Look Up The Names for US AutomaticL.
Hence We Have The Domain Name System (DNS). There Are Nodes with Well
KNown IP Addresses Which Program Can Ask to Look Up Names, And Return
IP Addresses. Almost All Programs You Will Use Are Capable Of Doing
This, Which is why you can put `www.linuxcare.com 'Into Netscape,
Instead of `167.216.245.249 '.
Of Course, You NEED The IP Address of At Least One of these `Name
Servers ': USUALLY THESE CEPT IN The `/etc/resolv.conf' file.
Since DNS Queries and Responses Are Fairly Small (1 Packet Each), THE
TCP Protocol Is Not Usually Used: It Provides Automatic
Retransmission, Ordering and General Reliability, But at a cost
Sending Extra Packets Through The Network. Instead We Use The Verysimple `User DataGram Protocol ', Which Doesn't Offer Any of The Fancy
TCP Features We don't need.
[1M6. Different Services: Email, Web, FTP, Name Serving [0M
In the earlier example, we showed netscape sending a TCP Request to a
Web Server Running On Another Node. But Imagine That The Node with
The Web Server IS Also Running An Email Server, An FTP Server and A
Name Server: How does it know Which Server The TCP Connection Is for?
This Is Where TCP AND UDP HAVE A Concept of `Ports'. Every Packet HAS
Space for a `Destination Port ', Which Says What Service the Packet IS
For example, tcp port 25 is the mail server, and tcp port 80 IS
The Web Server (Although Sometimes You Find Web Servers on Different
Ports). A List of ports can be found in `/ etc / services'.
Also, IF TWO Netscape Windows Are Both Accessing Different Parts of
The Same Web Site, How Does The Linux Box Running Netscape Sort Out
The TCP Packets COMING Back from the web server?
This is where the `source port 'comes in: Every New TCP Connection
Gets a Different Source Port, So Everyone Can Tell The Apart, Even IF
THEY Are Going to the Same Destination IP Address and The Same
Destination Port. Usually the First Source Port Given Will BE 1024,
And will increase over time.
[1M7. Dialup Interfaces: PPP [0M
When You Dial your model to an an isp, and it connects to their modem,
The Kernel Doesn't Just Shove IP Packets THROUGH It. There Is A
Protocol Called `Point-to-point protocol ', or` ppp', Which is buy
Negotiate with the Other End Before Any Packets Are Allowed THROUGH.
THIS Used by the ISP to Identify Who is Dailed Up: On Your Linuxbox, a Program Called The `PPP Daemon 'Handles your end of the
Negotiation.
Because there is so many dialup users in the world, they usually
Don't have their own ip address: Most Isps Will Assign you ONE OF
THEIRS TEMPORARILY WHEN You Dial Up (The Ppp Daemon Will Negotiate
this). this is offen called a `Dynamic IP Address', as Separate from
A `Static IP Address' Which is The Normal Case Where You Have Your Own
Address Permanently. Usually They Are Assigned by ModeM: The Next
Time You Dial Up, You Will Probably Get a Different Modem in the MODEM
Pool, And Hence A Different IP Address.
[1M8. What Packets Look Like [0M
For the Exceptionally Curious (and the curiously exception), Here IS
a description of what a packet activity looks like. There Are SEveral
Tools Which Watch What Packets Are Passing In and out of Your Linux
Box: The Most Common One IS `Tcpdump '(Which Understands More TCP
These Days, But a nice one is `Ethereal '. Such Programs Are Known
AS `packet sniffers'.
The Start of Each Packet Says Where It's Going, WHERE IT CAME FROM,
The Type of the Packet, And Other Administrative Details. This Part
IS Called The `packet header '. The rest of the packet, containing the
Actual Data Being Transmitted, IS Usually Called The `Packet Body '.
SO Any IP Packet Begins with An `IP Header ': at Least 20 Bytes long.
IT Looks Like (This Diagram RFC 791):
. ------- ------- ------------------------------- --------------.
| Version | IHL | TYPE OF Service | Total Length |
| ------- ------- ------------------------------- -------------- || Identification | Flags | FRAGMENT OFFSET |
| --------------- ------------------------------- -------------- |
| TIME TO LIVE | Protocol | Header CHECKSUM |
| --------------- ------------------------------- -------------- |
Source Address |
| ----------------------------------------------------------------------------- -------------- |
| Destination Address |
`------------------------------------- -------------- '
The Important Fields Are The Protocol, Which Indicates WHETHER this IS
A TCP Packet (Number 6), A UDP Packet (Number 17) OR Something Else,
The Source IP Address, And The Destination IP Address.
Now, IF The Protocol Fields Says this is a tcp packet, THEN A TCP
Header Will Immediely Follow this IP Header: The TCP Header IS Also
AT Least 20 Bytes Long:
. ------------------------------------- --------------.
Source Port | Destination Port |
| --------------------------------------------------------------------------------------------- -------------- |
| Sequence Number |
| ----------------------------------------------------------------------------- -------------- |
| ACKNOWLEDGMENT NUMBER |
| ------------------ - - ----------------- -------------- |
| Data | | U | A | P | r | s | f | |
| Offset | Reserved | R | C | S | S | Y | i | Window |
| | | G | K | H | T | N | N | |
| ------- ---------- - - - --------------- -------------- || CHECKSUM | Urgent Pointer |
`------------------------------------- -------------- '
The Most Important Fields Here Are The Source Port, And Destination
Port, Which Says Which Service The Packet Is Going To (or Coming from,
In The Case of Reply Packets. The Sequence and AcknowledgementGEment
Numbers Are Used to Keep Packets in Order, And Tell The Other End What
Packets have been received. The Ack, SYN, RST and FIN FLAGS (Written
Downwards) Are Single Bits Which Are Used to Negotiate THE OPENING
(SYN) And Closing (RST or FIN) of connections.
FOLLOWING THIS Header Comes The Actual Message Which the Application
Sent (The Packet Body). A Normal Packet IS Up To 1500 Bytes: This
Means That The Most Space The Data Can Take Up IS 1460 BYTES (20 BYtes
For the ip header, and 20 for the tcp header: Over 97%.
[1M9. Summary [0M
So the modeln internet uss ip packets to communicate, and most
THESE IP Packets Use TCP Inside. Special Nodes Called `Routers'
Connect All The Little Networks Together Into Larger Networks, And
Pass these packets through to their destination. Most Normal Machines
Are ONLY Attached to One Network (IE. Have Only One Interface), Ando
Are Not Routers.
Every Interface Has A Unique IP Address, Which Look Like `1.2.3.4 ':
Interfaces in the Same Network Will Have Related IP Addresses, with
The Same Start, The Same That That Phone Connections in The Same Area
Have The Same Prefix. The Same Prefix. The Same Network Addresses Look Like IP Addresses,
With a `/ 'to say how much of itm is the prefix, eg` 1.2.0.0/16'
Means The First Two Digits Is The Network Address: Each DigitRepresents 8 Bits.
Machines Are Given Names by The Domain Name Service: Programs Ask Name
Servers to Give The THE IP Address, Given a Name Like
`www.linuxcare.com '. this ip address is the name sale as the destination
IP address to talk to That node.
Rusty Is Really Bad At Writing Documentation, Especially For
Beginners.
Enjoy!
Rusty.
[1M10. Thanks [0M
Thanks to Alison, for Sitting THROUGH THE ORIGINAL TERRIBLE DRAGH, AND
Telling Me How Shit It Was, In The Nicest Possible Way.
[1M11. INDEX [0M
O `` 100baset ''
o `` 10Base2 ''
O `` 10baset ''
O `` Broadcast Address ''
O `` Coax, Coaxial Cable ''
o `` Computer network ''
o `` Default Route ''
O `` destination port ''
O `` DNS, Domain name service ''
O `` Dynamic IP Address ''
o `` ethernet ''
O `` fiber ''
O `` Gigabit Ethernet ''
O `` hop ''
o `` hub ''
o `` Internet ''
O `` ip, internet protocol ''
O `` ip address ''
O `` ip header ''
O `` IPv4, IP Version 4 ''
O `` IPv6, IP version 6 ''
O `` Lan, Local Area Network ''
O `` link-level protocol ''
o `` Modem ''
O `` Name Server ''
O `` Netmask ''
O `` network address, network mask ''
O `` network interface, interface ''
O `` network link ''
O `` network protocol, protocol ''
o `` node ''
o `` packet body ''
O `` packet header ''
O `` packet sniffer ''
o `` packet ''
O `` Port, TCP port, udp port ''
O `` PPP, Point-to-Point Protocol ''
o `` PPP daem ''
o `` protocol stack ''
o `` Retransmission ''
o `` Route ''
o `` Router ''
o `` routing ''
o `` sneakernet ''
o `` Source Port ''
o `` star-topology ''
O `` static ip address ''
O `` sub-network ''
O `` TCP, Transmission Control Protocol ''
o `` tcp header ''
o `` Terminator ''
O `` Topology ''
O `` UDP, User DataGram protocol ''
O `` Utp, unshielded twisted pair ''
O `` Wan, Wide Area Network ''
