IP Networking, Web, & Network Security 101
“Building Your Foundation”
Overall Agenda



Introduction
Internet & Web basics
IP addressing




Classes & CIDR Blocks
AS Numbers
DHCP, BGP, NAT
Network Security


Encryption
Firewalls
January, 2005
GTCC
2
Internet & Web Overview
The Internet & Web: Revolution Or Hype!!!

Is it:


Tulip mania?
Or is it:

A new revolution & scaling of economies (not
unlike the railroads in 1835)
 Going from local to national to global
January, 2005
GTCC
4
Changing Business Environments


Moving to a digital, information-based economy
More complex & faster-paced


“virtual offices”, “Internet time”, “coopetition”, “disintermediation”
Issues of primary concern to businesses

Improve the supply chain - tighten integration with suppliers




No matter their size - increases efficiency and barriers to competition
Strengthen the demand chain - deepen relationships with
customers and creating new distribution channels
Accelerate time-to-market - extend geographic reach without
bricks and mortar
Focus on core competencies - reduce costs while increasing
levels of service
January, 2005
GTCC
5
What’s Driving All The Excitement








Virtual Private Networks (VPN)
Audio and video conferencing
Business Applications
Entertainment
Collaboration
Commerce
E-mail
Virtual marketing
January, 2005
GTCC
6
Benefits to the Corporation





Increase revenues
Boost sales force productivity
Reduce marketing expense and increase
exposure
Increase customer satisfaction, but reduce
support costs
Boost overall corporate productivity everyone on-line
January, 2005
GTCC
7
Internet & Web Basics
January, 2005
GTCC
8
The Internet Past and Present (Great ROI For $25M)












1969 - ARPANET networking research - the start of the Internet ( first Man on Moon, Nixon Inaugurated,
Woodstock in NY and Sesame Street debuts)
1972 - E-mail( Nixon visits China, Dow hits 1,000, Watergate Scandal unfolds, FedEx and Nike founded)
1973 - International connections & Ethernet (Godfather II released,Foreman defeats Frazier, Agnew resigns,
Ford is new VP, World Trade Center is opened, and Roe V Wade)
1983- All computers on Arpanet must use TCP/IP. (cell phones make first appearance in Chicago,Australia wins
Americas Cup, Michael Jackson releases Thriller)
1984 DNS introduced (Mac PC introduced, Olympic games in L.A., Reagan reelected, McEnroe wins U.S.open
and Wimbledon)
1986 - NSFNET created (Platoon is Best Picture, Chernobyl explodes, Ivan Boesky pleads guilty to insider
trading)
1990 - Commercialization of the Internet( East and West Germany Unite, Dances with wolves wins best picture,
Hubbell telescope placed in Orbit)
1992 - World Wide Web is introduced ( 1,000,000 computers on Net. John Gotti Convicted, Euro Disney opens,
Clinton elected, L.A. Riots).
1993-INTERNIC formed to register IP and Domain Names (Elvis stamps Debut, Trade center bombed,
Schindlers list wins best picture, 51 day standoff in Waco)
1995-NSFNET turns internet over to private sector & starts Internet II.. The revolution begins (Oklahoma City
bombing, O.J. Bronco Chase, Dow hits 5,000. Dean Martin dies. Silence of the Lambs wins Oscar)
Today, growing faster than any sector

In two years Internet access audience greater than number of households with Televisions after 40 years
Future: E-everything
January, 2005
GTCC
9
ARPANet Circa 1977
January, 2005
GTCC
10
How The Internet Works


Data is passed from one network to another by ISP’s

Traffic is passed by “peering” (cross-connecting) the networks at defined
locations - Internet Exchange Points (IXPs)
 IXP locations
 Network Access Points (NAPs)
 Original jump-on points from old NSFNet
 PB NAP - San Francisco Bay Area, Ameritech NAP Chicago, Sprint NAP - New York City (Pensauken, NJ)
 Metropolitan Area Exchange (MAE)
 Developed by MFS
 MAE East - Washington D.C., MAE West - San Francisco
Bay Area, MAE-LA, MAE-Dallas, MAE-Chicago
 Palo Alto Internet Exchange (PAIX) & NASA
Of the 7,000 plus ISP’s just in North America, only a select handful are large
enough to peer, the rest buy transit
January, 2005
GTCC
11
Also, The Internet Is Packet Switched Not
Circuit Switched
•
•
•
Circuit Switched Networks:
• 23 or 24 simultaneous connections
•
56/64 kbps of bandwidth per connection, bandwidth reserved whether used or not
Packet Switched Networks
• 200 simultaneous connections possible
•
7.7 kbps average per user, total bandwidth shared amongst “n” users
So, a single T-1 with packet data handles 8x the users, costs far less than equivalent circuit
switched facilities
Packet Switched
Circuit Switched
January, 2005
GTCC
12
So, The Internet Is A Collection Of Large
ISP Infrastructures
UUNet
Public Peering Point
MCI
XO
Sprint
AOL
January, 2005
GTCC
13
Public NAP’s Are Located Around The Country
(Network Access Point)
Chicago NAP (AADS)
MAE Chicago
Palo Alto IX
Pacific Bell NAP
NASA
Sprint NAP
MAE West
MAE East
MAE LA
Public Peering Point
January, 2005
MAE Dallas
GTCC
14
This Peering Allows Customers Of ISP “A” To
Communicate With Customers Of ISP “B”
IXP
ISP “A”
Network
ISP “B”
Network
ISP “C”
Network
January, 2005
GTCC
15
But Not All Is Right In Mayberry!!!

Public Peering Locations Are Severely
Congested

NAPs - given to the private sector from the
government

So bad that NSF (National Science Foundation) officially
cut ties to the Internet May 13th, 1995


Government since has developed Internet II
 Only select government agencies and research
institutions may jump-on
Not all IXPs are telco hardened data centers

MAE-East is in an underground parking garage

January, 2005
Supposedly, 70% of Internet traffic goes through MAE-East
GTCC
16
To Solve The Problem, ISPs Privately Peer!
UUnet
AOL
Private Peering Point
Exodus
XO
NTT
PSI
HKT
GX
January, 2005
GTCC
17
Private Peering Has To Be Mutually Advantageous!
(Both Parties Have Large Amounts Of Data That Need To Be
Transferred Between Each Other)
UUnet
January, 2005
XO
GTCC
18
AT&T Asia
Sprint
Digex
IDC
Above
C&W
PSI
PAIX
UUnet
San Francisco
California
Exodus
Teleglobe
Qwest
NYIIX
AADS
NAP
AUCS
New York
New York
AMS-IX
Amsterdam
Holland
MAE
Frankfurt
Mountain View
California
Santa Clara
California
deCIX
SFINX
MAE
Paris
Paris
France
PARIX
Exodus
C&W
Sprint
Frankfurt
Germany
BIG
ISP.com
AGIS
PB
NAP
KTHNOC
Stockholm
Sweden
Netscape
MAE
West
LINX
London
England
Palo Alto
California
AT&T
SwissCom
Level3
UUnet
NASA
AMES
Teleglobe
Exodus
Sprint
Chicago
Illinois
UUnet
AT&T
San Jose
California
Qwest
Pennsauken
New Jersey
MAE ATM
West
Dallas
Texas
Level3
Ashburn
Virginia
UUnet
Los Angeles
California
MAE
LA
AOL
MAE ATM
Central
Teleglobe
Exodus
Qwest
Level3
January,
LA PB
NAP
2005
LAIIX
PSI
Exodus
MAE ATM
East
Sprint
NAP
Washington
DC
AOL
MAE
East
Level3
Qwest
Sprint
PSI
C&W
GTCC
UUnet
19
Vixie
Genuity
Singtel
Telstra
ConXioN
Netcom
4200
UOI
France
Telecom
IBM.IL
NAPnet
Net
NetCO
Inter
Acces
DRAnet
OAR
Scruz
Verio
KDD
Stanford
Teleglobe
ESnet
Alpha
Dot
Digex
@Home
Verio
OneCall
IGN
Genuity
NetRail
Global
Center
IIJ
Cerfnet
IGN
DEC
CAIS
I1
Argonne
AT&T
Disc
CERN
MIX
IconNet
GoodNet
CRL
AT&T
ELI
IconNet
ELI
Quza
Epoch
IDT
CET
Global
Center
Nuri
Road
Runner
Exodus
FiberNet
ISBEnet
Above
NWU
Globix
Road
Runner
Data
Place
HK Tel
N
IDC
Above
Exodus
CP
AT&T Asia
Sprint
Digex
NYIIX
Palo Alto
California
AT&T
UUnet
AUCS
Exodus
New York
New York
Chicago
Illinois
UUnet
NASA
AMES
AADS
NAP
Sprint
San Francisco
California
PAIX
Teleglobe
A
C&W
PSI
Qwest
UUnet
AGIS
LINX
London
England
KTHNOC
Stockholm
Sweden
AMS-IX
Globix
Road
Runner
TW
HE.net
San Jose
California
MAE ATM
West
Dallas
Texas
Level3
Ashburn
Virginia
UUnet
NetRail
MAE
LA
Los Angeles
California
AOL
MAE ATM
Central
Teleglobe
@home
Qwest
LA PB
NAP
Level3
Interpath
Exodus
LAIIX
Exodus
MAE ATM
East
Pennsauken
New Jersey
J
deCIX
MAE
Paris
I
H
AT&T
Sprint
NAP
Washington
DC
G
F
AOL
MAE
East
Level3
Sprint
Qwest
PSI
Megs
Inet
E
C&W
Data
Place
Voicenet
Above
AT&T
Disc
Road
Runner
@Home
Cable
Inet
Erols
Globix
KDD
IDT
DTAG
IGN
UUnet
PSI
D
Voicenet
Global
Center
Road
Runner
Los
Netos
Genuity
Epoch
Above
Cerfnet
January,
2005
BBN
Globix
Road
Runner
Oleane
TW
Gridnet
CAIS
Above
Digex
AT&T
Disc
Voicenet
Global
Center
GTCC
TW
K
PARIX
Qwest
BBN
Paris
France
L
MAE
Frankfurt
SFINX
Exodus
C&W
Sprint
Frankfurt
Germany
BIG ISP.com
Santa Clara
California
PB
NAP
C
M
Amsterdam
Holland
Mountain View
California
MAE
West
SwissCom
Level3
Netscape
B
Teleglobe
IIJ
Digex 20 ESnet
CRL
NAPnet
Netcom
Scruz
EUnet
Lighting
Net
Access
IGN
ICONnet ConXioN
EUnet
FiberNet
Wirehub
TTSG
Zocalo
Colt
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
LINX
Above
Well
Planet
Online
GoodNet
ESnet
NASA
AT&T
Disc
DPnet
IDT
CERFnet
Digex
LINX
LINX
LINX
LINX
Linkage
Erols
ELI
LINX
LINX
LINX
LINX
Brainstorm Nacamar
Verio
CAIS
IDC
Verio
A
M
B
dGIX
dGIX
dGIX
dGIX
dGIX
dGIX
dGIX
dGIX
dGIX
dGIX
dGIX
dGIX
dGIX
dGIX
dGIX
dGIX
InTouch
Surfnet
Support
Net
BBN
IGN
Euronet
UUnet
NL
Wirehub
Telanor
Eunet
Belnet
Sprint
Intl’
Cistron
Media
ways
L
C
BIG ISP.com
K
D
J
E
Compu
Serve
I
F
H
G
Netcom
MIBX
NetAsset
Well
PBI
Net
Konect
ServInt
AIN
IIJ
OneCall
Getnet
DTAG
Gridnet
GoodNet
EUnet
AGIS
Genuity
AGIS
Global
Center
ConXioN
Erols
FiberNet
CERFnet
CRL
Verio
@Home
NAPnet
CRL
Singtel
NetRail
TEN
Teleglobe
MAI
IGN
France
Telecom
Digex
Above
Epoch
ConXioN
IDT
Erols
Genuity
2005
WireHub
CAIS
ELI
dGIX
N
Data
Exchange
AT&T
dGIX
ScruzJanuary,
Vixie
Netnews Nacamar
NASA
Cabletel
GTCC
Data
NetRail
Exchange
FCI
Interpath
EuroNet
ELI
ConXion
Netcom
ESnet
A200021
INS
Smaller ISPs Must Rely On Severely Congested
“Public Peering” Locations, Or Transit From A
Larger ISP
NAP
NAP
ISP
ISP
ISP
January, 2005
GTCC
22
AS Numbers:
An ISP’s Social Security Number
January, 2005
GTCC
23
AS Numbers - Networks on the Internet


Every network on the Internet has a unique identifier or AS number.

AS = Autonomous System

Without an AS number you cannot tell the world about your content, you
cannot announce your routes, you cannot have BGP

Managed and controlled by ARIN
XO is ASN 2828, XO Europe is ASN 5413

ASN 5413 announces all of AS 2828…

UUNET is ASN 701

Genuity (BBN) is ASN 1 (they were the first)

etc...
January, 2005
GTCC
24
Where ISP’s are on the Internet.
January, 2005
GTCC
25
San Jose
Public Peering
- MAE-West
- PB-NAP
- PAIX
Private Peering
- UUnet
- Cable & Wireless
- Sprint
- Level (3)
- Exodus
- Abovenet
- PSInet
- Qwest
- Genuity
- @Home
- Global Center
- KDD
- IDC
- Hong Kong Tel
- etc.
Los Angeles
Public Peering
- MAE LA
- LA PB-NAP
Private Peering
- UUnet
- Sprint
- Level (3)
- Exodus
- Abovenet
- PSInet
- Qwest
- Global Center
- Teleglobe
January,
- etc... 2005
Example of US Internet Peering Infrastructure
New York
Public Peering
- Sprint-NAP
Private Peering
- UUnet
- Cable & Wireless
- Sprint
- Level (3)
- Exodus
- Abovenet
- PSInet
- Teleglobe
- Bell Canada
- etc...
Chicago
Public Peering
- AADS
Private Peering
- UUnet
- Cable & Wireless
- Sprint
- Level (3)
- Abovenet
- PSInet
- Qwest
- Genuity
- @Home
- Global Center
- etc.
Dallas
Public Peering
- MAE ATM
Private Peering
- UUnet
- Level (3)
- Genuity
- @Home
GTCC
Washington, DC
Public Peering
- MAE-East
- Equinix
Private Peering
- UUnet
- Cable & Wireless
- Sprint
- Level (3)
- AOL
- Exodus
- Abovenet
- PSInet
- Qwest
- Genuity
- @Home
- Global Center
- etc...
To Europe
26
Example Of European Internet Peering Infrastructure
London
Stockholm
Public Peering
Public Peering
- LINX
- KTHNOC
Private Peering
To USA
- Infonet Europe
Amsterdam
- Abovenet
Public Peering
- Ebone
- AMS-IX
Paris
Public Peering
Public Peering
- PARIX
- deCIX
- SFINX
January, 2005
Frankfurt
GTCC
27
So, You Want To Be An ISP

You will need:

An AS Number (BGP requires it)
 Without you can’t be identified
 Get it from ARIN

Public/Private peering or transit relationships
 Almost impossible to get peering now days (usually
done through acquisition)

DNS, email, web servers, etc.

IP address blocks from ARIN

24x7 technical & support staff

Solid infrastructure of routers, switches, servers, etc.

And last……….LOTS OF MONEY
January, 2005
GTCC
28
The Internet Is Truly A “Network Of Networks”
January, 2005
GTCC
29
Some Of The Nuts & Bolts
January, 2005
GTCC
30
OSI vs. TCP/IP

Both have been around since the 70’s
OSI
Application (Layer 7)
TCP/IP
Presentation (Layer 6)
Application
Session (Layer 5)
Transport (Layer 4) Transmission Control
Network (Layer 3)
Internet
Data Link (Layer 2)
Physical (Layer 1)
January, 2005
Subnet
GTCC
31
What Is TCP/IP??


IP: connectionless protocol
 Responsible for the sending/routing of IP
Datagrams
 Analogy: sending a letter
TCP: connection-oriented protocol
 Responsible for reliable transport of IP Datagrams
 Analogy: placing a phone call
January, 2005
GTCC
32
The IP Protocol





Performs packetization of user data
IP is the hatchet man of the protocol stack- it
segments and packets data in Datagrams, but IP
has not intelligence
Puts header on datagram and shoots it out.
Datagrams can take various paths/ no assurance
of arrival or arriving uncorrupted
Allows nodes to read header and route to next
downstream connection. If anything on Network
path gets corrupted the Datagram is discarded.No
return message saying Datagram did not arrive .
This simplicity improves Network efficiency
January, 2005
GTCC
33
The TCP Protocol



Transmission Control Protocol provides the
brains to overcome IP
At receiving end it puts data back into its
proper sequence and ensures accuracy
At sending end
 Puts a byte count header in the Datagram
for comparison at receiving end. If Data is
corrupted or does not arrive a message is
sent back requesting the data again.
January, 2005
GTCC
34
TCP Continued!



TCP also holds all Datagrams (buffers them) until all
lost packets are re-sent and able to be assembled in
their proper order.
This makes data reception and accuracy the
responsibility of the end user and not the Network.
TCP orchestrates the connection
The network is only a transport system not a
computer processing function
January, 2005
GTCC
35
IP Addressing
January, 2005
GTCC
36
Binary Math: The Foundation of IP Addressing

Computers use the binary numbering system (on/off)

1’s and 0’s or the power of 2

Number of 1’s/0’s determines number of unique combinations
 The longer the string the more unique combinations

But who can remember all those 1’s and 0’s, so here’s an easy way to
convert
7
2
6
2
1
0
128 64 32 16 8
4
2
1
1
0
0
1
0 16 8
0
0
1
0
2
3
2
0
2
4
2
128 0
January, 2005
5
2
1
2
1
GTCC
2
= 153
37
IP Addressing



An IP address is a software-based numeric identifier
assigned to each machine on an IP network.
Each Computer is distinguished by this unique IP
address.
Combination of 32 ones and zeros
 eg. 11100011.00010100.11111001.1010101
identifies one unique computer host
January, 2005
GTCC
38
IP Addressing Continued

Two methods of IP Addressing
 Class based
 An IP address is organized into 4 groups of 8bit
numbers such as:199.232.255.113
 Classless based
 An IP address is organized into one block of 32 bits,
counting right to left in decreasing order
-------- /24 /25 /26 /27 /28 /29 /30 /31
=
-------- 256128 64 32 16 8
January, 2005
GTCC
4
2
39
IP Addresses



IP addresses are made up of network and host addressesin 199.232.255.113 the 199.232.255 is the Network address shared by
every machine on that network. The .113 is the host address assigned
to a particular machine.
IP addresses are difficult to remember so domain names are mapped
to each IP address
January, 2005
GTCC
40
IP Addresses Can Be Broken Into Classes

Class A’s, B’s, C’s, D’s, & E’s
 But only Class A’s through C’s have really been
used.
January, 2005
GTCC
41
Class A addresses


Class A networks- the El grande of IP
networks
Only 126 class A addresses are possible. Each
Class A network can have in excess of 16
million computers in its individual networks
January, 2005
GTCC
42
Class B addresses

Class B Networks- Can have 65,000
workstations on the network. There are
approximately. 65,000 Class B networks
January, 2005
GTCC
43
Class C addresses

Class C Networks- can have 254 workstations
on the network. There are several million
Class C Networks.
January, 2005
GTCC
44
CIDR Blocks



CIDR- Classless Internet Domain Routing.
With a New Network being connected to internet every 30
minutes the Internet faced two problems : Running out of IP
addresses. Running out of capacity in the global routing tables
Because Addresses were only assigned in three classes there
was a lot of wasted addresses… IE. If you needed 100
addresses you would be assigned a Class C. But that meant 154
addresses were unused. CIDR solutions- replaces old wasteful
practice of assigning class B&C addresses. ALLOWS FOR
ARBITRARY SIZED NETWORKS
January, 2005
GTCC
45
MORE CIDR


An ISP can carve out a block of registered IP addresses to
specifically meet the needs of each client
CIDR allows a single routing table entry to specify how to route
traffic to many individual network addresses. This route
aggregation helps control the amount of routing information on
the Internets backbone routers.
January, 2005
GTCC
46
CIDR



A CIDR address includes the standard 32-bit IP
address and also information on how many bits are
used for the network prefix.
In the CIDR address 206.13.01.48/24, the "/24"
indicates the first 24 bits are used to identify the
unique network leaving the remaining 8 bits to
identify the specific hosts… or 256
5
So if someone
asks for a / 27 they are telling you in
geek speak they need 25 or 32 IP addresses
January, 2005
GTCC
47
IP Address & Domain Name Registration


Responsibility for management/distribution of IP addresses handled
by 3 Regional Internet Registries (RIR)
 ARIN - American Registry for Internet Numbers
 RIPE - Reseaux IP Europeens
 APNIC - Asia Pacific Network Information Center
ARIN requirements
 Must use 50% of IP address allocation immediately
 Must use 80% of IP address allocation within 6 months
 Must use 100% of IP address allocation by year end
 If not, and ISP is audited, customer may have to turn-in all
addresses
January, 2005
GTCC
48
North America - Domain Names Are
Registered With Network Solutions
(And Others)


Used to be called InterNIC
 Cooperative effort between the U.S. Government and a private
company, Network Solutions (Now Verisign)
(www.networksolutions.com) (www.netsol.com)
 Currently, about 15 other companies compete with Network
Solutions for domain name registration
 Management & distribution of domain names
Once the domain name is registered, Network Solutions propagates
the name to all the domain name system (DNS) servers on the
Internet
January, 2005
GTCC
49
An IP Example!!!


The Internet is divided into addressing Domains
Within a domain detailed information is available about all networks that reside in
that domain. Outside the domain, only the network prefix is advertised. This allows a
single routing table entry to specify a route to many network addresses
200.25.0.0/16
one routing table for all
these networks and hosts
200.25.46.0/20
Internet
ISP
200.25.16.0/21
Organization A
January, 2005
200.25.16.0/24
200.25.17.0/24
200.25.18.0/24
200.25.19.0/24
200.25.20.0/24
Organization B
200.25.24.0/22
200.25.24.0/24
200.25.25.0/24
200.25.26.0/24
GTCC
200.25.30.0/23
Organization C
200.25.30.0/24
200.25.31.0/24
50
How Do You Know How Many IP
Addresses You Need?




Three IP’s are always “non” usable
 In, Out, and CPE (Network, Gateway, and Broadcast)
How many hosts/computers/PCs, etc. does the customer have
Does the customer own their own IP address block?
What is the future growth of the customer?
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But These Decimal Based IP Addresses
Are Hard To Remember!!!
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Enter Domain Names!!!
Enter Domain Names?

What is a Domain Name?

A company’s Internet Identity

A company’s online brand

Something easy to remember

Totally unique

Addressing construct used for identifying & locating computers on
the Internet.


xo.com Represents the Company XO Communications.


www.xo.com = 38.195.90.87
When you type xo.com in a web browser or send e-mail to
someone at xo.com, the Domain Name System (DNS) translates
xo.com into the IP numbers used by the Internet.
Resides on a computer called a the Domain Name Server
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What is the Domain Name System?





Method for computers to contact each other to exchange email and
display Web pages using IP address information
Distributed database used to translate domain names into IP
addresses.
Maintains specific portion of that global database for a company
Specific company data held in each portion of the database and is
made available to all computers and users on the Internet.
Comprised of computers, data files, software, and people working
together so interoperable communications are possible.
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What are Domain Name Servers?


Connected Internet with special software to translate Domain Names into
numerical addresses or IP Addresses
Two types of Domain Name Servers : Local and Global

Local Name Servers


House all the names and IP addresses for your local network
devices

Maintain the local DNS database information

Usually a Primary and Secondary Local Domain Name Server Exist
Global Name Servers


House the names and IP addresses for all of the Local Name
Servers connected to the Internet.
Public Registries (like Network Solutions, a.k.a. InterNIC) maintain
the global DNS database information.
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How the Domain Stuff Works….
1. You request IP address info for www.XO.com (an “A” record)
2. The Local Name Server has no idea who
www.xo.com is….so the request is
forwarded to a Global Name Server
www.xo.com
Local Name Server
Browser Joe
www.xo.com
206.129.70.23
6. Your Web browser now
uses the IP address to
contact the proper site
www.xo.com
206.129.70.23
The
Internet
Global Name Server
(Public Registry)
www.xo.com
206.129.70.23
3. The Global Name Server
knows of a Primary
Local Name Server that
might know the info and
forwards…..
Web Site
January, 2005
Primary
Local Name Server
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5. The info is forwarded
back to the Global
Name Server
4. The Primary Local Name
Server didn’t know but
the Secondary Local
Name Server did
Secondary
Local Name Server
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How does e.mail work ?
1. Mail Server A requests IP address info for the MX of xo.com
2. The Local Name Server has no idea what
MX address for xo.com is….so the request is
forwarded to a Global Name Server
MX for XO.com
Mail Server A
Local Name Server
Mail Hosting Provider
MX for xo.com
206.129.70.22
To: Sue@xo.com
Subject: Party!
The Internet
Global Name Server
(Public Registry)
6. Mail Server A now
uses the IP address to
forward the mail to Mail
Server B
Mail Server B
Mail Hosting Provider
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MX for xo.com
206.129.70.22
3. The Global Name Server
knows of a Primary
Local Name Server that
might know the info and
forwards…..
Primary
Local Name Server
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5. The info is forwarded
back to the Global
Name Server
4. The Primary Local Name
Server didn’t know but
Secondary
the Secondary Local
Local Name Server Name Server did
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So what if more than one internet
connection is required?
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You Need Border Gateway Protocol (BGP)!!!



Border Gateway Protocol :
Addresses what path a packet will
take to get to its destination
BGP maintains routing tables that
list all feasible paths to a particular
network
The Primary function of a BGP
system is to exchange Network
Reachability information, including
information about the list of
autonomous system paths, with
other BGP systems…BGP is the
way a system says I know how to
deliver packets to this destination
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BGP Continued


So Who needs this stuff
ISPs that have more than one peering point (US)

A company that wants to be multihomed to
different ISPs (Two connections Via different
service providers)
 With One upstream provider you only have one
path out of your network and you are on their
CIDR block anyway.
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Additional Internet Routing Stuff!!!
Routing Vs. Bridging
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What’s the difference between bridging and
routing?
Bridging
Basic access to the Internet.
No IP associated with the actual bridge.
Think of a Bridge like a piece of wire connected directly to your
workstation.
Routing
More secure than a Bridge.
Has a WAN and LAN IP.
Think of a Router like a box with side A and B. Each side had an IP.
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Bridging
No, but I’ll ask the
No, but let me
I just found this guy reading the book. ask the guy that’s
next to me.
wallet on the
floor. Are you
Naw, it’s not mine.
John Doe?
Hey, you in the red tie,
are you John Doe?
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Yes, I’m John Doe
and that’s my wallet
-- thanks a million!
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Routing
I have a wallet for a
John Doe at 555-1234.
Yes, I’m John Doe. I’m so glad
you found me right away -- I’ll
take it!
Can’t miss
my plane!
Blah, blah,
blah...
January, 2005
Blah, blah...
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Network Address Translation (NAT)
LAN
Internet
NAT Device



Uses a translation protocol to turn private, non
Internet routable addresses into addresses that
can be routed over the public Internet.
Hides internal IP addresses to the Internet (a
basic firewall)
Can not Telenet/Can not host multiple servers of
the same protocol
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
NAT Continued
 Allows an organization to present itself to the internet with
one IP address
 XO Customer Network private numbering allows LAN’s to
utilize fewer public IP addresses.
 Standard Protocol - helps preserve unlimited use of IP
addresses. Allows customer independence by being in
control and managing their own internal IP addressing
scheme.
 Enables a company to use as many internal IP’s as
needed without having to renumber machines if ISP’s
change
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NAT in Action
Network Address Translation Hotel
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Network Address Translation



A list at the front desk of each client registered to
what room.
 Configured client list within the router
 Customer is responsible for completing the
configuration
The bell boy checks the list
 Router reads the list
Bell Boy delivers mail the to the correct room.
 Router delivers internet traffic to requested
MAC address
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Benefits of NAT


Hotel Security
 Basic level of security on a private network
 Protects users anonymity
Cheaper than purchasing IP addresses for each individual user
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IP Addresses - Public and Non Public
Private Network
Public IP Address
10.10.10.1
130.5.0.1
10.10.10.2
10.10.10.3
10.10.10.4
Internet
10.10.10.5
Router
10.10.10.6
…
10.10.10.253
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So, Define NAT
Network Address Translation: An Internet standard that enables a
local area network (LAN) to use one set of IP addresses for
internal traffic and a second set of addresses for external use.
How much does NAT cost?
NO ADDED COST!!!
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Dynamic Host Configuration Protocol (DHCP)

What is it???
 Allows IP addressing information to be dynamically
assigned by a server to clients on an as-needed
basis.
 IP addresses are stored in a pool
 Allocated to computers on a network as they log on
 IP addresses are returned to the pool when the
client or computer logs off
 Automatic assignment frees IT staff to deal with
other pressing company needs
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CONFIGURATION OF DHCP


In order to configure routers for DHCP the following information
is necessary:
 Does the customer want NAT also? Yes or no
 Does the customer want public or private addressing
 DHCP server IP address pool
 Customer Domain Name
ISP will provide to the customer:
 IP address of the DNS (Domain Name Service) Server
 IP address block (pool)
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DHCP Review
Define DHCP
Dynamic Host Configuration Protocol. DHCP is a TCP/IP protocol that
enables PC’s and workstations to get temporary or private IP addresses
from a pool in a centrally administered server.
Name a benefit of DHCP
DHCP frees up time for customer IT employees in order to take care of
other company needs. Saves $$
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The World Wide Web
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World Wide Web = Vast Collection of
Internet-Accessible Information (Web Sites)
We
b
Sit
e
We
b
Sit
e
We
b
Sit
e
Internet
We
b
Sit
e
We
b
Sit
e
We
b
Sit
e
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We
b
Sit
e
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Web Browsers Enable Computers To Access
The Web & view Web sites


Web browsers reside on the user’s computer
 Based on the particular operating system used by the
user
 MAC OS, Windows, NT, UNIX
Major Web browsers
 Netscape Navigator
 Microsoft Internet Explorer
 AOL (which is based on Microsoft Internet Explorer)
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Web Sites Are Collections Of Individual
Web Pages
Web Site
January, 2005
Page
A
Page
B
Page
C
Page
D
Page
E
Page
F
Page
G
Page
H
Page
I
Page
G
Page
K
Page
K
Page
M
Page
N
Page
O
Page
P
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Web Site have Unique Addresses Called Domain Names or
URLs (Uniform Resource Locator)
Corvette Mike Web Page
Index
Home
Red
Corvette
Blue
Corvette
White
Corvette
Silver
Corvette
Black
Corvette
Green
Corvette
Prices
Order
Info
Parts
Stores
Corvette
History
Hot Rod
Tips
Compan
y
History
About
Mike
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http://www.corvettemike.com
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Each page within the Web site has its
own unique URL
For Sale
Mint
New Paint
Restored
357 V-8
4-Speed
$25,000
http://www.corvettemike.com/red_corvette.html
Call Corvette Mike today!
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Each Web Page Consists Of An HTML File &
Related Photo & Graphic Files
For Sale
Mint
New Paint
Restored
For Sale
357 V-8
4-Speed
$25,000
Call Corvette Mike today!
HTML Text and Page Layout
Mint
New Paint
Restored
Background
357 V-8
4-Speed
$25,000
Call Corvette Mike today!
Pictures
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Graphics
82
When Users Request A Web page - Web
Server Copies & Sends the files
For Sale
Mint
New Paint
Restored
357 V-8
4-Speed
$25,000
Call Corvette Mike today!
User
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http://www.corvettemike.com/red_vette.html
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Web Server
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User’s Web Browser Reads The HTML File &
Assembles The Page
For Sale
For Sale
Mint
New Paint
Restored
357 V-8
4-Speed
$25,000
Mint
New Paint
Restored
Call Corvette Mike today!
357 V-8
4-Speed
$25,000
Call Corvette Mike today!
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How Are Web Sites Built?
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Three Basic Methods Of Building A Web Site
1) Build the site yourself using a browser-based site builder provided by a Web host
2) Build the site yourself using a popular Web development software program
3) Hire a professional Web Developer
4) Program the Web site in HTML
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Regardless of the method used, all Web pages are written
in HTML (Hypertext Markup Language)
HTML can be read by any computer -- regardless of the type of computer operating system
Mac OS
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Windows
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UNIX
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Once complete, the Web site files are uploaded
to the Web Server.
1) The user can transfer the files from the PC to the Web Server using the File Manager function
/web
Upload File
2) If the site is built with Microsoft FrontPage, the user can use the Microsoft FrontPage “publish”
feature, which transfers files to the Web server automatically
3) The user can also use FTP (File Transport Protocol) software
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Advanced Web Site Features!
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SSL (Secure Socket Layer) Security
SSL: SSL is a technology that provides security for Web site
transactions. SSL handles authentication and data encryption between
a Web browser and a Web server. Most electronic commerce
applications on the Web use SSL.
Secure
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Not Secure
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CGI (Common Gateway Interface) scripts
CGI Scripts: A standard way for a Web server to pass a user's request
to an application program and to receive data back to forward to a user.
CGI scripts are small programs that are written into HTML.
Examples
Description
Counters
Counts and displays hits to a Web page
Form2file
Takes user form data and writes it to a file
Form2mail
Collect, e-mail, and save form data based on templates
Gen-form
Collect and e-mail form data to one or more addresses.
Go There
A replacement for hyperlinks
Image Maps
Create click-able areas on any image
Nph-pusher
Create animations from separate image files
Simple-search
Search a text file for a key word and return records that contain that key word
Survey
Collect, tabulate, and display survey data via the Web
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In Summary





Internet is the infrastructure that WWW rides on
It is truly ubiquitous
It drives the cost of doing business down
It levels the playing field for all companies
It is NOT Hype, it is a revolution
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