Transcript Chapter 6

Chapter 6: Introduction to the IP
Protocol
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Chapter 6 Objectives
The Following CompTIA Network+ Exam Objectives Are
Covered in This Chapter:
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5.2 Explain the basics of network theory and concepts
• TCP/IP suite
o ICMP
o UDP
o TCP
5.9 Compare and contrast the following ports and protocols
• 80 HTTP
• 443 HTTPS
• 137-139 Netbios
• 110 POP
• 143 IMAP
• 25 SMTP
• 5060/5061 SIP
• 2427/2727 MGCP
• 5004/5005 RTP
• 1720 H.323
• TCP
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o Connection-oriented
Chapter 6 Objectives (cont.)
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5.10 Given a scenario, configure and apply the appropriate ports and
protocols
• 20,21 FTP
• 161 SNMP
• 22 SSH
• 23 Telnet
• 53 DNS
• 67,68 DHCP
• 69 TFTP
• 445 SMB
• 3389 RDP
3.0 Network security
3.2 Compare and contrast common network vulnerabilities and
threats
Vulnerabilities
o Unsecure protocols
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TELNET
HTTP
SLIP
FTP
TFTP
SNMPv1 and SNMPv2
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Chapter 6 Objectives (cont.)
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3.3 Given a scenario, implement network hardening techniques
• Use secure protocols
o SSH
o SNMPv3
o TLS/SSL
o SFTP
o HTTPS
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What is TCP/IP?
• Because TCP/IP is so central to working with the
Internet and intranets, it’s essential for you to
understand it in detail.
• TCP/IP first came on the scene in 1973. Later, in 1978,
it was divided into two distinct protocols: TCP and IP.
• Then, back in 1983, TCP/IP replaced the Network
Control Protocol (NCP) and was authorized as the
official means of data transport for anything connecting
to ARPAnet, the Internet’s ancestor that was created
by ARPA, the DoD’s Advanced Research Projects
Agency way back in 1957 in reaction to the Soviet’s
launching of Sputnik.
• ARPA was soon re-dubbed DARPA, and it was divided
into ARPAnet and MILNET (also in 1983); both were
finally dissolved in 1990.
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TCP/IP History
• Most of the development work on TCP/IP happened at
UC Berkeley in Northern California, where a group of
scientists were simultaneously working on the Berkeley
version of UNIX, which soon became known as the
BSD, or Berkeley Software Distribution series of UNIX
versions.
• Of course, because TCP/IP worked so well, it was
packaged into subsequent releases of BSD UNIX and
offered to other universities and institutions if they
bought the distribution tape.
• All of this led to the DoD model….
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DoD Model
The DoD model is basically a condensed version of the
OSI model—it’s composed of four, instead of seven,
layers:
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Process/Application layer
Host-to-Host layer
Internet layer
Network Access layer
• The figure on the next slide shows a comparison of the
DoD model and the OSI reference model. As you can
see, the two are similar in concept, but each has a
different number of layers with different names.
• However, the DoD and OSI are so similar that the layer
names are actually interchangeable.
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DoD Model
DoD Model
Process/
Application
OSI Model
Application
Presentation
Session
Host-to-Host
Transport
Internet
Network
Network
Access
Data Link
Physical
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TCP/IP Protocol Suite
DoD Model
Process/
Application
Telnet
TFTP
Network
Access
LPD
NFS
TCP
Host-to-Host
Internet
FTP
SMTP
UDP
ARP
IP
ICMP
Ethernet
SNMP
X Window
Fast
Ethernet
Gigabit
Ethernet
RARP
Wireless
/802.11
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TCP/IP Protocols (cont)
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Telnet - 23
FTP - 20,21
SFTP - 22
TFTP - 69
SMTP - 25
POP - 110
IMAP4 - 143
RDP – 3389
TLS/SSL – 995/465
SIP (VOIP) – 5060/5061
RTP – 5004/5005
SNMP - 161
SSH - 22
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TCP/IP Protocols
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HTTP - 80
HTTPS - 443
NTP - 123
LDAP - 389
IGMP - network layer (no port number)
NetBIOS - 137-139
SMB - 445
DNS - 53
DHCP – 67/68
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DHCP Client four-step process
Client Broadcast
DHCPDiscover
Server Unicast
DHCPOffer
Client Broadcast
DHCPRequest
Server Unicast
DHCPACK
“DORA”
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Host-to-Host Layer Protocol
• Two protocols at this layer
– Transmission Control Protocol (TCP)
– User Datagram Protocol (UDP)
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TCP Segment
Bit 15 Bit 16
Bit 0
Source Port (16)
Bit 31
Destination Port (16)
Sequence Number (32)
Acknowledgement Number (32)
Reserved (6)
Code
bits (6)
Checksum (16)
24 bytes
Header
Length (4)
Window (16)
Urgent (16)
Options (0 or 32 if any)
Data (varies)
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UDP Segment
Bit 15 Bit 16
Bit 0
Bit 31
Destination Port (16)
Length (16)
Checksum (16)
6 Bytes
Source Port (16)
Data
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TCP and UDP
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Chapter 6
Port numbers for TCP and UDP
Figure 6.6
Application
layer
Port numbers
Transport
layer
FTP
Telnet
Doom
DNS
TFTP
POP3
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23
666
53
69
110
TCP
UDP
News
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Port Number Examples
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IP Header
Bit 0
Version
(4)
Header
Length (4)
Bit 15 Bit 16
Priority and
Type of Service (8)
Total length (16)
Flags
(3)
Identification (16)
Protocol (8)
Fragmented offset (13)
Header Checksum (16)
20 bytes
Time to Live (8)
Bit 31
Source IP Address (32)
Destination IP address (32)
Options (0 or 32 if any)
Data (varies if any)
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ICMP Example
e0 on Lab_B is down. Host A is trying to communicate to Host B. What happens?
Lab_A
Lab_B
e0
e0
icmp
X
Host A
Host B
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ARP Example
I heard that broadcast.
The message is for me.
Here is my Ethernet address.
I need the Ethernet
address of 10.1.1.2
10.1.1.1
10.1.1.2
IP: 10.1.1.2 = ???
IP: 10.1.1.2
Ethernet: 45:23:79:85:77:34
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RARP Example
What’s my IP
address?
I heard that broadcast.
Your IP address
is 192.168.10.3
Ethernet: 45:23:79:85:77:34 IP = ??
Ethernet: 45:23:79:85:77:34
IP: 192.168.10.3
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Data Encapsulation
PDU
Application
Presentation
Upper layer data
Session
TCP Header
Upper layer data
IP Header
Segment
LLC Header
Packet
FCS
MAC Header
Packet
FCS
0101110101001000010
Segment
Transport
Packet
Network
Frame
Data Link
Bits
Physical
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Protocol Data Units
Segment
Source
Port
Destination
Port
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Data
Packet
Source IP
Destination
IP
Protocol
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Segment
Frame
Destination
MAC
Source
MAC
Ether-Field
Packet
FCS
Bits
1011011100011110000
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Port Numbers at the Transport
Layer
Source
Port
Destination
Port
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Host Z
Host A
SP
DP
1028
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Defines Virtual Circuit
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Defines upper layer
process or application
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Summary
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Summary
Exam Essentials Section
Written Labs
Review Questions
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