Network Protocols
Why Protocols?
 Rules
and procedures to govern
communication


Some for transferring data
Some for route discovery
TCP/IP
 Suite
of Protocols to define communication
 Application – client functionality
 Transport - moving data
 Network – tasks for moving data
Steps –Sending
 Protocol
responsible for breaking data into
smaller parts called packets
 Network address is attached to packet
 Data prepared for transmission and sent
through NIC
Steps - Receiving
 Data
received, taken off network through
NIC
 Address information stripped
 Data packets are resembles
 Packets are then sent to application for
use.
Common Protocols
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TCP
FTP
UDP
TCP/IP
DHCP
TFTP
DNS
HTTP
ARP
SIP


RTP
SSH
 POP3
 NTP
 IMAP4
 TELNET
 SMTP
 SNMP
 ICMP
 IGMP
 TLS
TCP
 Transmission
Control Protocol
 Connection oriented – establishes a
manually acknowledged session between
two hosts.
 Provides reliability to IP
 Flow control, sequencing, and error
detection and correction.
 Transport layer
TCP Connection
 Sends
SYN to target host
 Target opens connection and sends ACK
 Originated host sends ACK ready to
transfer data
 Called three-way handshake
UDP
 User
Datagram Protocol
 No guarantee delivery
 “fire and forget”
 Uses IP
 Transport layer
 Lower overhead – low bandwidth
FTP
 File
Transfer Protocol
 Uploading and downloading of files
 Uses TCP as a transport protocol
 Used to transfer files over the LAN

Popular to distribute files over the internet
 Application
layer
Common FTP commands
 know
SSH
 Secure
Shell
 Alternative to telnet
 Provides security and encryption
 Allows sessions to be opened on a remote
host
SFTP
 Secure
File Transfer Protocol
 Authentication between sender and
receiver
 Encryption – if packets copied remain
hidden
 Implemented though client and server
software
 Allows for securely uploading and
downloading files to and from remote host
TFTP
 Trivial
File Transfer Protocol
 File transfer
 Not the same file security and functionality
as FTP
 Simple downloads – firmware
 No directory navigation
 Uses UDP
 Application layer
SMTP
 Simple
Mail Transfer Protocol
 How mail is sent/transported through the
network
 TCP
 Can be used to send and receive mail
 authentication
HTTP
 Hypertext
Transfer Protocol
 Uses TCP
 Allows text, graphics, multimedia and
other material to be downloaded
 Requests sent in clear text
HTTPS
 Hypertext
Transfer Protocol Secure
 SSL – encrypts
 Both the client and server must support
POP3/IMAP4
 Post
Office Protocol 3/ Internet Message
Access Protocol
 Can download email but not send
 Passwords transferred in clear text
Telnet
 Virtual
terminal protocol
 Allows session to be opened and
commands executed
 Used to access routers and other network
devices
 Not secure
ICMP
 Internet
Control Message Protocol
 Works with the IP layer to provide error
checking and reporting
 Tools to provide best-delivery
 PING
 Used for error reporting, flow control, and
route testing
ARP
 Address
Resolution Protocol
 Resolving IP addresses to MAC
addresses
RARP
 Reverse ARP
 Resolves
MAC to IP addresses
 Reveres lookups in DNS
Network Time Protocol NTP
 Facilitates
the communication of time
between systems
 Important for email and directory services
Network News Transfer Protocol
NNTP
 Posting
and retrieval of messages
 Application layer
Secure Copy Protocol SCP
 Secure
means of copying files
 Encrypts data
 More secure then RCP
Lightweight Directory Access
Protocol LDAP
 Access
and query directory services
 NDS and ADS
Internet Group Management
Protocol IGMP
 Manages
multicast
 Used to register and discover devices
 Routers and videoconferencing clients
Domain Name Service DNS
 Resolves
host names to IP addresses
 Used to use txt file hosts
WINS
 On
windows allows NetBIOS names to be
resolved to IP addresses.
 If no WINS server use LMHOSTS file
Simple Network Management
Protocol SNMP
 Network
management of devices
Dynamic Host Configuration
Protocol DHCP
 Automatically
assigns IP addresses
 Allows a range of IP addresses to be
defined
 Clients ask the server for and address
 Lease - scope
Transport Layer Security TLS
 Ensure
privacy between client/server apps
Session Initiation Protocol SIP
 VOIP
 Establish
and maintain multimedia
sessions

Internet telephone calls
 Uses
TCP or UDP
 Application layer
Real Time Transport Protocol
RTP
 Transport
of real-time data
 Does not guarantee delivery
 Transport Layer
Ports
 Each
protocol needs a port to access and
leave the system
Ports
 TCP/IP
has 65,535 ports
 Well known – 0-1023
 Registered ports – 1024-49151

Used by apps or services
 Dynamic

or private – 49152 – 65353
Can be used for any service or app
– 20 – TCP
 FTP – 21 TCP
 SSH – 22 TCP
 Telnet – 23 – TCP
 SMTP – 25 – TCP
 DNS – 53 – UDP/TCP
 TFTP – 69 – UDP
 HTTP – 80 – TCP/UDP
 POP3 – 110 – TCP
 FTP
– 119 – TCP
 NTP – 123 – TCP
 IMAP4 – 143 – TCP
 SNMP – 161- UDP
 HTTPS – 443 – TCP
 DHCP – 67 - UDP
 NNTP
IP Address
 Consists
of a series of 32 binary bits
 Grouped into four 8-bit bytes


Called and octet
Presented in decimal value
 Composed


of two parts
First part – network
Second part - host
Example
 192.168.18.57

First three octets are network
• 192.168.18

Last octet identifies the host
• 57
Address Ranges

Class
Address Range

A
10.0.0.0-10.255.255.255
255.0.0.0

B
172.16.0.0-172.31.255.255
255.255.0.0

C
192.168.0.0-192.168.255.255 255.255.255.0
Default Subnet
Mask
Need to Know
 169.254.0.0-
no DHCP server to give
address
 127 loopback
Class
 IP

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


addresses are divided into 5 classes
Class A – large networks
Class B – medium sized networks –
universities
Class C – small networks – ISP’s for
customers
Class D – multicasting
Class E - testing
Subnet Mask
 Network
portion of the address
 Hosts on a LAN use the same subnet
mask
Subnet Mask cont
 Class A –
255.0.0.0
 Class B – 255.255.0.0
 Class C – 255.255.255.0