Network ProtocolsNetwork Protocols

Why Protocols?Why Protocols?

Rules and procedures to govern Rules and procedures to govern communicationcommunication Some for transferring dataSome for transferring data Some for route discoverySome for route discovery

TCP/IPTCP/IP

Suite of Protocols to define communicationSuite of Protocols to define communication Application – client functionalityApplication – client functionality Transport - moving dataTransport - moving data Network – tasks for moving dataNetwork – tasks for moving data

Steps –SendingSteps –Sending

Protocol responsible for breaking data into Protocol responsible for breaking data into smaller parts called packetssmaller parts called packets

Network address is attached to packetNetwork address is attached to packet Data prepared for transmission and sent Data prepared for transmission and sent

through NICthrough NIC

Steps - ReceivingSteps - Receiving

Data received, taken off network through Data received, taken off network through NICNIC

Address information strippedAddress information stripped Data packets are resemblesData packets are resembles Packets are then sent to application for Packets are then sent to application for

use.use.

Common ProtocolsCommon Protocols

TCPTCP FTPFTP UDPUDP TCP/IPTCP/IP DHCPDHCP TFTPTFTP DNSDNS HTTPHTTP ARPARP SIPSIP

RTPRTP SSHSSH POP3POP3 NTPNTP IMAP4IMAP4 TELNETTELNET SMTPSMTP SNMPSNMP ICMPICMP IGMPIGMP TLSTLS

TCPTCP

Transmission Control ProtocolTransmission Control Protocol Connection oriented – establishes a Connection oriented – establishes a

manually acknowledged session between manually acknowledged session between two hosts.two hosts.

Provides reliability to IP Provides reliability to IP Flow control, sequencing, and error Flow control, sequencing, and error

detection and correction.detection and correction. Transport layerTransport layer

TCP ConnectionTCP Connection

Sends SYN to target hostSends SYN to target host Target opens connection and sends ACKTarget opens connection and sends ACK Originated host sends ACK ready to Originated host sends ACK ready to

transfer datatransfer data Called three-way handshakeCalled three-way handshake

UDPUDP

User Datagram ProtocolUser Datagram Protocol No guarantee deliveryNo guarantee delivery ““fire and forget”fire and forget” Uses IPUses IP Transport layerTransport layer Lower overhead – low bandwidthLower overhead – low bandwidth

FTPFTP

File Transfer ProtocolFile Transfer Protocol Uploading and downloading of filesUploading and downloading of files Uses TCP as a transport protocolUses TCP as a transport protocol Used to transfer files over the LANUsed to transfer files over the LAN

Popular to distribute files over the internetPopular to distribute files over the internet Application layerApplication layer

Common FTP commandsCommon FTP commands

knowknow

SSHSSH

Secure ShellSecure Shell Alternative to telnetAlternative to telnet Provides security and encryptionProvides security and encryption Allows sessions to be opened on a remote Allows sessions to be opened on a remote

hosthost

SFTPSFTP

Secure File Transfer ProtocolSecure File Transfer Protocol Authentication between sender and receiverAuthentication between sender and receiver Encryption – if packets copied remain Encryption – if packets copied remain

hiddenhidden Implemented though client and server Implemented though client and server

softwaresoftware Allows for securely uploading and Allows for securely uploading and

downloading files to and from remote hostdownloading files to and from remote host

TFTPTFTP

Trivial File Transfer ProtocolTrivial File Transfer Protocol File transferFile transfer Not the same file security and functionality Not the same file security and functionality

as FTPas FTP Simple downloads – firmwareSimple downloads – firmware No directory navigationNo directory navigation Uses UDPUses UDP Application layerApplication layer

SMTPSMTP

Simple Mail Transfer ProtocolSimple Mail Transfer Protocol How mail is sent/transported through the How mail is sent/transported through the

networknetwork TCPTCP Can be used to send and receive mailCan be used to send and receive mail authenticationauthentication

HTTPHTTP

Hypertext Transfer ProtocolHypertext Transfer Protocol Uses TCPUses TCP Allows text, graphics, multimedia and Allows text, graphics, multimedia and

other material to be downloadedother material to be downloaded Requests sent in clear textRequests sent in clear text

HTTPSHTTPS

Hypertext Transfer Protocol SecureHypertext Transfer Protocol Secure SSL – encrypts SSL – encrypts Both the client and server must supportBoth the client and server must support

POP3/IMAP4POP3/IMAP4

Post Office Protocol 3/ Internet Message Post Office Protocol 3/ Internet Message Access ProtocolAccess Protocol

Can download email but not sendCan download email but not send Passwords transferred in clear textPasswords transferred in clear text

TelnetTelnet

Virtual terminal protocolVirtual terminal protocol Allows session to be opened and Allows session to be opened and

commands executedcommands executed Used to access routers and other network Used to access routers and other network

devicesdevices Not secureNot secure

ICMPICMP

Internet Control Message ProtocolInternet Control Message Protocol Works with the IP layer to provide error Works with the IP layer to provide error

checking and reportingchecking and reporting Tools to provide best-deliveryTools to provide best-delivery PINGPING Used for error reporting, flow control, and Used for error reporting, flow control, and

route testingroute testing

ARPARP

Address Resolution ProtocolAddress Resolution Protocol Resolving IP addresses to MAC Resolving IP addresses to MAC

addressesaddresses

RARPRARP

Reverse ARPReverse ARP Resolves MAC to IP addressesResolves MAC to IP addresses Reveres lookups in DNSReveres lookups in DNS

Network Time Protocol NTPNetwork Time Protocol NTP

Facilitates the communication of time Facilitates the communication of time between systemsbetween systems

Important for email and directory servicesImportant for email and directory services

Network News Transfer Protocol Network News Transfer Protocol NNTPNNTP

Posting and retrieval of messagesPosting and retrieval of messages Application layerApplication layer

Secure Copy Protocol SCPSecure Copy Protocol SCP

Secure means of copying filesSecure means of copying files Encrypts data Encrypts data More secure then RCPMore secure then RCP

Lightweight Directory Access Lightweight Directory Access Protocol LDAPProtocol LDAP

Access and query directory servicesAccess and query directory services NDS and ADSNDS and ADS

Internet Group Management Internet Group Management Protocol IGMPProtocol IGMP

Manages multicastManages multicast Used to register and discover devicesUsed to register and discover devices Routers and videoconferencing clientsRouters and videoconferencing clients

Domain Name Service DNSDomain Name Service DNS

Resolves host names to IP addressesResolves host names to IP addresses Used to use txt file hostsUsed to use txt file hosts

WINSWINS

On windows allows NetBIOS names to be On windows allows NetBIOS names to be resolved to IP addresses.resolved to IP addresses.

If no WINS server use LMHOSTS fileIf no WINS server use LMHOSTS file

Simple Network Management Simple Network Management Protocol SNMPProtocol SNMP

Network management of devicesNetwork management of devices

Dynamic Host Configuration Dynamic Host Configuration Protocol DHCPProtocol DHCP

Automatically assigns IP addressesAutomatically assigns IP addresses Allows a range of IP addresses to be Allows a range of IP addresses to be

defineddefined Clients ask the server for and addressClients ask the server for and address Lease - scopeLease - scope

Transport Layer Security TLSTransport Layer Security TLS

Ensure privacy between client/server appsEnsure privacy between client/server apps

Session Initiation Protocol SIPSession Initiation Protocol SIP

VOIP VOIP Establish and maintain multimedia Establish and maintain multimedia

sessionssessions Internet telephone callsInternet telephone calls

Uses TCP or UDPUses TCP or UDP Application layerApplication layer

Real Time Transport Protocol Real Time Transport Protocol RTPRTP

Transport of real-time dataTransport of real-time data Does not guarantee deliveryDoes not guarantee delivery Transport LayerTransport Layer

Ports Ports

Each protocol needs a port to access and Each protocol needs a port to access and leave the systemleave the system

PortsPorts

TCP/IP has 65,535 portsTCP/IP has 65,535 ports Well known – 0-1023Well known – 0-1023 Registered ports – 1024-49151 Registered ports – 1024-49151

Used by apps or servicesUsed by apps or services Dynamic or private – 49152 – 65353Dynamic or private – 49152 – 65353

Can be used for any service or appCan be used for any service or app

FTP – 20 – TCPFTP – 20 – TCP FTP – 21 TCPFTP – 21 TCP SSH – 22 TCPSSH – 22 TCP Telnet – 23 – TCPTelnet – 23 – TCP SMTP – 25 – TCPSMTP – 25 – TCP DNS – 53 – UDP/TCPDNS – 53 – UDP/TCP TFTP – 69 – UDPTFTP – 69 – UDP HTTP – 80 – TCP/UDPHTTP – 80 – TCP/UDP POP3 – 110 – TCP POP3 – 110 – TCP

NNTP – 119 – TCPNNTP – 119 – TCP NTP – 123 – TCPNTP – 123 – TCP IMAP4 – 143 – TCPIMAP4 – 143 – TCP SNMP – 161- UDPSNMP – 161- UDP HTTPS – 443 – TCPHTTPS – 443 – TCP DHCP – 67 - UDPDHCP – 67 - UDP

IP AddressIP Address

Consists of a series of 32 binary bits Consists of a series of 32 binary bits Grouped into four 8-bit bytes Grouped into four 8-bit bytes

Called and octetCalled and octet Presented in decimal valuePresented in decimal value

Composed of two parts Composed of two parts First part – networkFirst part – network Second part - hostSecond part - host

ExampleExample

192.168.18.57 192.168.18.57 First three octets are networkFirst three octets are network

• 192.168.18192.168.18 Last octet identifies the host Last octet identifies the host

• 5757

Address RangesAddress Ranges

ClassClass Address Range Address Range Default Subnet Default Subnet MaskMask

AA 10.0.0.0-10.255.255.25510.0.0.0-10.255.255.255 255.0.0.0 255.0.0.0

BB 172.16.0.0-172.31.255.255 255.255.0.0172.16.0.0-172.31.255.255 255.255.0.0

CC 192.168.0.0-192.168.255.255 192.168.0.0-192.168.255.255 255.255.255.0 255.255.255.0

Need to KnowNeed to Know

169.254.0.0- no DHCP server to give 169.254.0.0- no DHCP server to give addressaddress

127 loopback127 loopback

ClassClass

IP addresses are divided into 5 classesIP addresses are divided into 5 classes Class A – large networksClass A – large networks Class B – medium sized networks – Class B – medium sized networks –

universitiesuniversities Class C – small networks – ISP’s for Class C – small networks – ISP’s for

customerscustomers Class D – multicastingClass D – multicasting Class E - testingClass E - testing

Subnet MaskSubnet Mask

Network portion of the addressNetwork portion of the address Hosts on a LAN use the same subnet Hosts on a LAN use the same subnet

maskmask

Subnet Mask contSubnet Mask cont

Class A – 255.0.0.0Class A – 255.0.0.0 Class B – 255.255.0.0Class B – 255.255.0.0 Class C – 255.255.255.0Class C – 255.255.255.0