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CIS 1140 Network Fundamentals

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1 CIS 1140 Network Fundamentals
Chapter Four: Introduction to TCP/IP Protocols Collected and Compiled By JD Willard MCSE, MCSA, Network+, Microsoft IT Academy Administrator Computer Information Systems Instructor Albany Technical College

2 Attention: Accessing Demos
This course presents many demos. The Demos require that you be logged in to the Virtual Technical College web site when you click on them to run. To access and log in to the Virtual Technical College web site: To access the site type in the url window Log in using the username: CIS 1140 or ATCStudent1 Enter the password: student (case sensitive) If you should click on the demo link and you get an Access Denied it is because you have not logged in to or you need to log out and log back in. If you should click on the demo link and you are taken to the web site page you should do a search in the search box for the CompTIA Network+ (2009 Objectives) Course and run the video from within that page.

3 Objectives Identify and explain the functions of the core TCP/IP protocols Explain the TCP/IP model and how it corresponds to the OSI model Discuss addressing schemes for TCP/IP in IPv4 and IPv6 protocols Discuss addressing schemes for TCP/IP in IPv4 and IPv6 and explain how addresses are assigned automatically using DHCP (Dynamic Host Configuration Protocol) Describe the purpose and implementation of DNS (Domain Name System) Identify the well-known ports for key TCP/IP services Describe how common Application layer TCP/IP protocols are used

4 Network Protocols A Protocol is a set of standards or rules that governs how networks communicate Protocols often provide services, such as or file transfer. Most protocols are not intended to be used alone, but instead rely on and interact with other dependent or complimentary protocols Protocols vary according to their purpose, speed, transmission efficiency, utilization of resources, ease of setup, compatibility, and ability to travel between different LANs. Multiprotocol networks: networks running more than one protocol A group of protocols that is intended to be used together is called a protocol suite Most popular protocol suite is TCP/IP Others: IPX/SPX, NetBIOS, and AppleTalk Network Protocols Defined Demo Understanding Network Protocols Demo Transport Protocols Demo

5 Characteristics of TCP/IP (Transmission Control Protocol/Internet Protocol)
TCP/IP is not one protocol but a suite of specialized protocols called subprotocols. Subprotocols include TCP, IP, UDP, ARP, ICMP, IGMP etc. Developed by US Department of Defense ARPANET (1960s) Internet precursor Advantages of TCP/IP Open nature Costs nothing to use Flexible Runs on virtually any platform Connects dissimilar operating systems and devices Routable Transmissions carry Network layer addressing information Suitable for large networks Introduction Demo Overview Demo TCP IP Basics Demo

6 TCP/IP Compared to the OSI Model
The TCP/IP suite of protocols can be divided into four layers that roughly correspond to the seven layers of the OSI Model. ■ Application layer — The Application layer corresponds to the Session, Presentation, and Application layers of the OSI model. Applications gain access to the network through this layer, via protocols such as the File Transfer Protocol (FTP), Trivial File Transfer Protocol (TFTP), Hypertext Transfer Protocol (HTTP), Simple Mail Transfer Protocol (SMTP), and Dynamic Host Configuration Protocol (DHCP). ■ Transport layer — This layer comparable to the Transport layer of the OSI model and contains the Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), which provide flow control, error checking, and sequencing. All service requests use one of these protocols. ■ Internet layer — This layer is comparable to the Network layer of the OSI model contains the Internet Protocol (IP), Internet Control Message Protocol (ICMP), Internet Group Message Protocol (IGMP), and Address Resolution Protocol (ARP). These protocols handle message routing and host address resolution. ■ Network access layer (or Link layer) — This layer corresponds to the functions of the Physical and Data Link layers of the OSI mode and is responsible for describing the physical layout of the network and how messages are formatted and transmitted to the network wire. The TCP/IP Model (5:00)    TCP/IP and OSI Models Demo 

7 The TCP/IP Suite Demo continued
The TCP/IP model compared with the OSI model The TCP/IP Suite Demo continued The TCP/IP Suite Demo The TCP/IP Suite Demo continued

8 The TCP/IP Core Protocols
TCP/IP suite subprotocols Operate in Transport or Network layers of OSI model Provide basic services to protocols in other layers Most significant protocols in TCP/IP suite TCP IP TCP/IP Suite Basics Demo Networking Protocols (6:17)

9 TCP (Transmission Control Protocol)
Transport layer protocol that operates host to host. Provides reliable data delivery services Connection-oriented subprotocol Establish connection before transmitting Uses sequencing and acknowledgements Provides flow control TCP segment format Encapsulated by IP packet in Network layer Becomes IP packet’s “data” Understanding TCP Demo

10 A TCP segment Transmission Control Protocol Demo
Connection Controls and Windowing Demo

11 TCP (cont’d.) The TCP three-way handshake is the process used to establish a TCP session. The steps to a TCP three-way handshake process are: A host sends a SYN packet to the target host. The target host responds to the original host with a SYN ACK packet. The host responds to the target host with an ACK packet. Establishing a TCP connection

12 UDP (User Datagram Protocol)
Transport layer protocol Provides unreliable data delivery services Connectionless transport service No assurance packets received in correct sequence No guarantee packets received at all Best effort delivery No error checking, sequencing Lacks sophistication More efficient than TCP Useful when large amounts of data need to be transferred quickly such as with live audio and video transmissions over the Internet. Understanding UPD Demo

13 UDP (User Datagram Protocol)
A UDP segment

14 IP (Internet Protocol)
Understanding IP Demo Network layer protocol How and where data delivered, including: Data’s source and destination addresses Addressing schemes: uses an IP address, such as and a Subnet Mask such as Enables TCP/IP to internetwork Traverse more than one LAN segment More than one network type through router Routing: Statically and Dynamically via many routing protocols; OSPF, BGP, RIP and EIGRP Network layer data formed into packets IP packet Data envelope that contains information for routers to transfer data between different LAN segments Unreliable, connectionless protocol Relies on upper layer protocols like TCP to ensure delivery and connection orientation Internet Protocol Demo TCP/IP Demo Pt.2

15 IP Packet IP datagram: packet, in context of TCP/IP Envelope for data
IP adds the following header fields to each packet: Source IP Address Destination IP Address Protocol Checksum Time to Live (TTL) An IPv4 packet

16 IGMP Operates at the Network layer of the OSI model and is a protocol for defining host groups Manages multicasting on networks running IPv4 Allows one node to send data to a defined group of nodes Similar to broadcast transmission All group members can receive broadcast messages intended for the group (called multicasts) Multicast groups can be composed of devices within the same network or across networks (connected with a router) Point-to-multipoint method Used for Internet teleconferencing or videoconferencing Understanding IGMP Demo

17 ARP (Address Resolution Protocol )
Network layer protocol used with IPv4 that provides IP address-to-MAC address name address resolution Obtains MAC (physical) address of host or node A host wishing to obtain a physical address broadcasts an ARP request onto the TCP/IP network. The host on the network that has the IP address in the request then replies with its physical hardware address. Creates database that maps MAC to host’s IP address ARP table (ARP Cache) Table of recognized MAC-to-IP address mappings Saved on computer’s hard disk Increases efficiency Contains dynamic and static entries Understanding ARP Demo ARP (4:02)

18 ICMP (Internet Control Message Protocol)
ICMP is commonly used for troubleshooting and information gathering. ICMP allows you to test the path (among other things). Ping and Tracert are two tools that can be used to test a path and they both use ICMP. ICMP packets will be able to help send information about errors, control, and other informational messages. Network layer protocol Reports on data delivery success/failure Announces transmission failures to sender Network congestion Data fails to reach destination Data discarded: TTL expired ICMP cannot correct errors Provides critical network problem troubleshooting information ICMPv6 used with IPv6 Understanding ICMP Demo

19 Connectivity Parameters
The following table summarizes the configuration settings required to connect to a TCP/IP network. Parameter Purpose IP address The IP address Identifies both the logical host and the logical network addresses. Each host on the entire network must have a unique IP address. Two devices on the same subnet must have IP addresses with the same network portion of the address. Two devices on the same subnet must have unique host portions of the IP address. Do not use the first or the last host address on a subnet address range. Subnet mask The subnet mask identifies which portion of the IP address is the network address, and which portion is the host address. Two devices on the same subnet must be configured with the same subnet mask. Default gateway The default gateway identifies the router to which communications for remote networks are sent. The default gateway address is the IP address of the router interface on the same subnet as the local host. Without a default gateway set, most clients will be unable to communicate with hosts outside of the local subnet. DNS server The DNS server address identifies the DNS server that is used to resolve host names to IP addresses. Host name The host name identifies the logical name of the local system.

20 IP Addressing Overview
IP Addresses Demo IP Addressing Demo Pt.1 IP Addressing Demo Pt.2

21 Addressing in TCP/IP Networks recognize two addresses
Logical (Network layer) Physical (MAC, hardware) addresses IP protocol handles logical addressing Specific parameters Unique 32-bit number Divided into four octets (sets of eight bits) separated by periods Example: Network class determined from first octet IP Address Demo  What is an IP Address? Demo Adding Protocols Demo

22 Binary and Dotted Decimal Notation
Common way of expressing IP addresses Decimal number between 0 and 255 represents each octet Period (dot) separates each decimal Each number in dotted decimal address has binary equivalent Convert each octet Remove decimal points Base 2 Numbering is Binary Consists of ‘0’ and ‘1’. Bits are either “Off” (0) or “On” (1) Computers like Binary! IP Addresses are comprised of four 8 bit octets that are expressed as a decimal number between 0 and 255 separated by a period Bit Value Bit = =179 Binary Math (7:59) A Binary Lesson Demo Binary Addressing Demo Solutions for Binary Demo

23 Binary to Decimal Conversions
Bit Number: Binary Equiv: Decimal Equiv: Binary Number: Decimal Equiv: = 157 1) Determine what decimal numbers in the table will create the number you want to make. 2) Enter a “1” under each value you must use. Enter a “0” for each value that is not used in the Binary Number line. 3) The resulting combination of 0’s and 1’s is the binary equivalent of the number.

24 Sample Binary to Decimal Conversion
Convert Decimal 5 to Binary Bit Number: Binary Equiv: Decimal Equiv: Binary Number: 4) Determine what decimal numbers in the table will create the decimal number 5 (4+1). 5) The resulting combination of is the binary equivalent of the decimal number 5.

25 Address Classes There are three primary classes of network addresses: A, B, and C. The actual class used is based on the size of the network. An IP address is accompanied by a subnet mask. Each address class has a different default subnet mask. IP addresses are expressed in dotted-decimal format, such as Each set of four dotted-decimal numbers represents eight bits of the binary address. The addresses range from to , or, in decimal notation, from 0 to 255. IP Address Classes Demo IP Classes (9:52) Address Classes Demo

26 Classful Addressing Adheres to network class distinctions
Only Class A, B, and C addresses are recognized Network ID limited to first 8 bits in Class A, first 16 bits in Class B, and first 24 bits in Class C Fixed network ID size ultimately limits number of hosts a network can include First Octet First Octet 128 – 191 First Octet Components of an IP Address Demo

27 Classful Addressing IPv4 addresses have a default class. The address class identifies the range of IPv4 addresses. The following table shows the default address class for each IPv4 address range. Class First Octet Range Number of Networks Maximum Addressable Hosts per Network A 1-126 126 ( to ) 16,777,214 ( to ) B 16,384 ( to ) 65,534 ( to ) C 2,097,152 ( to ) 254 ( to )

28 Reserved Addresses Certain types of IP addresses reserved for special functions Network ID Cannot Be 127 127 is reserved for lookback functions Network ID and Host ID Cannot Be 255 (All Bits Set to 1) In broadcast addresses, octet(s) representing host information set to all 1s (255 in decimal notation) 255 is a broadcast address Network ID and Host ID Cannot Be 0 (All Bits Set to 0) In network IDs, bits for host information set to 0 0 means “this network only” Host ID Must Be Unique to the Network IP Address Rules Demo

29 Addressing in TCP/IP ipconfig: Windows NT, XP, Vista, 2000, 2003, 2008 command to view IP information Winipcfg: Win98, ME ifconfig on Unix and Linux /all switch Results of the ipconfig /all command on a Windows XP or Windows Vista workstation Ipconfig Demo IPConfig,Ifconfig, Winipcfg Demo

30 What Is a Subnet Mask? In binary form, the subnet mask is always a series of 1's followed by a series of 0's (1's and 0's are never mixed in sequence in the mask). A simple mask might be Distinguishes the Network ID from the Host ID Combines with device IP address to mask the Network ID with all 1s Informs network about segment, network where device attached Used to specify whether the destination host is local or remote (ANDing) Four octets (32 bits) Expressed in binary or dotted decimal notation Assigned same way as IP addresses Manually or automatically (via DHCP) Subnet Mask Demo Subnet Masks Demo

31 Subnet Masks Every device on TCP/IP-based network identified by subnet mask 32-bit number that, when combined with device’s IP address, informs rest of network about segment or network to which a device is attached Subnetting, subdividing single class of networks into multiple, smaller logical networks or segments, depends on subnet masks to identify how a network is subdivided Indicates where network information is located in an IP address “1” bits indicate corresponding bits in IP address contain network information “0” bits indicate corresponding bits in IP address contain host information To calculate host’s network ID given IP address and subnet mask, perform ANDing Anding IP Addresses Demo Subnet Masks Demo Solutions for Masks Demo

32 Default Subnet Masks (No Subnetting)
Address Class Bits Used for Subnet Mask Dotted Decimal Notation Class A Class B Class C Class B Example IP Address 16.200 0.0 Subnet Mask Network ID y.z Host ID w.x. 16.200

33 IPv6 Addressing Composed of 128 bits Eight 16-bit fields
Typically represented in hexadecimal numbers Separated by a colon Example: FE22:00FF:002D:0000:0000:0000:3012:CCE3 Abbreviations for multiple fields with zero values 00FF can be abbreviated FF 0000 can be abbreviated 0 Multicast address Used for transmitting data to many different devices simultaneously Anycast address Represents any one interface from a group of interfaces Modern devices and operating systems can use both IPv4 and IPv6 Why IPv6? Demo IPv4 and IPv6 (5:18) IPv6 Basics Demo

34 ADDRESS ASSIGNMENT Because IP addresses assigned to hosts must be unique, the use of IP addresses on the Internet is controlled by organizations that ensure that no two organizations are given the same range of IP addresses to assign to hosts. The Internet Assigned Numbers Authority (IANA) manages the assignment of IP addresses on the Internet. IANA is operated by the Internet Corporation for Assigned Names and Numbers (ICANN). IANA allocates blocks of IP addresses to Regional Internet Registries (RIRs). An RIR has authority for IP addresses in a specific region of the world. An RIR assigns a block of addresses to Internet Service Providers (ISPs). An ISP assigns one or more IP addresses to individual computers or organizations connected to the Internet. On private networks IP addresses are assigned to computers either manually, called static addressing, or automatically through a DHCP server which is called dynamic address allocation. Configure TCP/IP Demo IP Address Assignment Demo Pt.1

35 DHCP (Dynamic Host Configuration Protocol)
Automatically assigns device a unique IP address Application layer protocol Reasons for implementing Reduce time and planning for IP address management Reduce potential for error in assigning IP addresses Enable users to move workstations and printers Make IP addressing transparent for mobile users DHCP leasing process Device borrows (leases) an IP address while attached to network Lease time Determined when client obtains IP address at log on User may force lease termination DHCP service configuration Specify leased address range Configure lease duration Several steps to negotiate client’s first lease Dynamic Addressing Demo Dynamic Clients Demo

36 DHCP Leasing Process Device borrows (leases) an IP address while attached to network Lease time Determined when client obtains IP address at log on User may force lease termination ipconfig /release DHCP service configuration Specify leased address range Configure lease duration Several steps to negotiate client’s first lease

37 DHCP Leasing Process DHCP Addressing Overview (4:35) The client goes through a four stage broadcast based process to obtain an IP Address lease from a DHCP server. Step 1: Upon bootup the client sends out a DHCPDISCOVER packet in broadcast fashion to discover the identity and whereabouts of all DHCP servers on the broadcast segment. Step 2: Upon receiving the broadcast any DHCP servers on that broadcast segment will respond with their own DHCPOFFER packet. Step 3: The client will accept the first offer received and respond with a DHCPREQUEST broadcast. Other DHCP servers who have made an offer hear this broadcast and return their IP address to the pool. Step 4: The chosen DHCP server responds with an DHCPACK confirming the clients acceptance of the IP lease along with additional information such as subnet mask, default gateway and DNS server.


39 IP Lease Renewal DHCP Leases (4:24)

40 Terminating a DHCP Lease
Lease expiration Automatic Established in server configuration Manually terminated at any time Client’s TCP/IP configuration Server’s DHCP configuration Circumstances requiring lease termination DHCP server fails and replaced Windows: release of TCP/IP settings DHCP services run on several server types Installation and configurations vary

41 Private Addresses Private addresses
Allow hosts in organization to communicate across internal network Cannot be routed on public network Specific IPv4 address ranges reserved for private addresses Addresses: 16,777,216 Addresses: 1,048,576 Addresses: 65,536 The private addressing works well for allowing computers to access resources inside the private network only Routers inside the private network can route traffic between private addresses with no trouble. To access the Internet, or a public network, computers have to have a public address. This is where Network Address Translation (NAT) comes into play. Routers on the Internet will not accept IP addresses in a private IP address range Special Addresses Demo

42 Link-Local Addresses APIPA (Automatic Private IP Addressing)
Provisional address Capable of data transfer only on local network segment APIPA is a Microsoft implementation of automatic IP address assignment without a DHCP server. Using APIPA, hosts assign themselves an IP address on the network (mask of ). With APIPA: The host is configured to obtain IP information from a DHCP server (this is the default configuration). If a DHCP server can't be contacted, the host uses APIPA to assign itself an IP address. The host only configures the IP address and mask. It does not assign itself the default gateway and DNS server addresses. For this reason, APIPA can only be used on a single subnet. Disadvantage Computer only communicates with other nodes using addresses in APIPA range APIPA (3:42) IP Address Assignment Demo Pt.2

43 Static (manual) Assignment
Using static addressing, IP configuration information must be manually configured on each host. Use static addressing: On networks with a very small number of hosts. On networks that do not change often or that will not grow. To permanently assign IP addresses to hosts that must always have the same address (such as printers, servers, or routers). For hosts that cannot accept an IP address from DHCP. To reduce DHCP-related traffic. Static addressing is very susceptible to configuration errors and duplicate IP address configuration errors. Static addressing disables both APIPA and DHCP capabilities on the host. Static Addressing Demo Static Clients Demo

44 Ports and Sockets Ports are logical connections, provided by the TCP or UDP protocols at the Transport layer, for use by protocols in the upper layers of the OSI model. TCP/IP uses port numbers stored in the header of a packet to determine what protocol incoming traffic should be directed to. Every process on a machine assigned a port number 0 to 65535 Process’s port number plus host machine’s IP address equals process’s socket Example: :53 Ensures data transmitted to correct application Well Known Ports: in range 0 to 1023 Assigned to processes that only the OS or system administrator can access Registered Ports: in range 1024 to 49151 Accessible to network users and processes that do not have special administrative privileges Dynamic and/or Private Ports: in range through 65535 Open for use without restriction Understanding Port Numbers Demo Common TCP and UDP Ports (8:09)

45 Sockets and Ports Well Known Port Numbers Demo
Commonly used TCP/IP port numbers

46 Name Resolution Overview
Name Resolution Overview Demo NetBIOS Name Resolution Demo Resolving a Host Name Demo DHCP/ DNS/WINS Servers Demo

47 Host Names and DNS (Domain Name System)
TCP/IP addressing Long, complicated numbers Good for computers People remember words better Internet authorities established Internet node naming system Host Internet device Host name Name describing device Every host can take a host name Host Naming Demo

48 Domain Names What is DNS? Demo Domain
Group of computers belonging to same organization Share common part of IP address Domain name Identifies domain ( Associated with company, university, government organization Fully qualified host name ( Local host name plus domain name Label (character string) Separated by dots Represents level in domain naming hierarchy Example: Top-level domain (TLD): com Second-level domain: google Third-level domain: www Second-level domain May contain multiple third-level domains ICANN established domain naming conventions Domain names must be registered with an Internet naming authority that works on behalf of ICANN What is DNS? Demo

49 Domain Names (cont’d.) ICANN approved over 240 country codes
Host and domain names restrictions Any alphanumeric combination up to 253 characters Include hyphens, underscores, periods in name No other special characters Structure of DNS Demo

50 Host Files ARPAnet used HOSTS.TXT file
Associated host names with IP addresses Host matched by one line Identifies host’s name, IP address Alias provides nickname UNIX-/Linux-based computer Host file called hosts, located in the /etc directory Windows computer Host file called hosts Located in Windows\system32\drivers\etc folder Host Name Resolution Demo

51 DNS (Domain Name System)
An Overview of DNS (8:12) Hierarchical method of associating domain names with IP addresses Refers to Application layer service that accomplishes association and organized system of computers and databases making association possible DNS redundancy Many computers across globe related in hierarchical manner Root servers 13 computers (ultimate authorities) Three components Resolvers Any hosts on Internet needing to look up domain name information Name servers (DNS servers) Databases of associated names, IP addresses Provide information to resolvers on request Namespace Abstract database of Internet IP addresses, associated names Describes how name servers of the world share DNS information Root Domain Name Servers Demo The DNS Namespace Demo

52 DNS Resource Records DNS Records (9:05) DNS Records Demo
Entries for hostnames, IP addresses, and other information in the zone database are stored in records. Each host has at least one record in the DNS database that maps the hostname to the IP address. The following table lists common resource records. The A record maps an IPv4 (32-bit) DNS host name to an IP address. This is the most common resource record type. The AAAA record maps an IPv6 (128-bit) DNS host name to an IP address. The CNAME record provides alternate names (or aliases) to hosts that already have a host record. Using a single A record with multiple CNAME records means that when the IP address changes, only the one A record needs to be modified. The MX record identifies servers that can be used to deliver . The PTR record maps an IP address to a host name (i.e. "points" to an A record). DNS Records (9:05) DNS Records Demo

53 Domain Name Space The Domain Name System (DNS) is a hierarchical, distributed database that maps logical host names to IP addresses. The DNS hierarchy is made up of the following components: . (dot) domain (also called the root domain) Top Level Domains (TLDs) such as .com, .edu, .gov Additional domains such as,, etc. Hosts The fully-qualified domain name (FQDN) includes the host name and all domain names, separated by periods. The final period (for the root domain) is often omitted and implied.

54 DNS Resolution Process
The client looks in its local cache to see if it has recently resolved the host name. If the information is not in the cache, it checks the Hosts file. If the IP address is not found, the host contacts its local DNS server. If the local DNS server can't be contacted, it continues contacting additional DNS servers until one responds. The client sends the name information to the DNS server. The DNS server then checks its cache and Hosts file. If the information is not found, the DNS server checks any zone files that it holds for the requested name. If the DNS server can't find the name in its zones, it forwards the request to a root zone server. This server returns the IP address of a DNS server that has information for the corresponding top-level domain (such as .com). The local DNS server then requests the information from the top-level domain server. This server returns the address of a DNS server with the information for the next highest domain (Microsoft). The local DNS server then requests the information from the Microsoft DNS server which holds the necessary information. This server returns the address of the requested host name. The local DNS server places the information in its cache and returns the IP address to the client. The client host also places the information in its cache and uses the IP address to contact the desired destination device. Resolving Name Resolution Demo

55 DDNS (Dynamic DNS) Dynamic DNS (DDNS) enables clients or the DHCP server to update records in the zone database. Without dynamic updates, all A (host) and PTR (pointer) records must be configured manually. With dynamic updates, records are created and deleted automatically. Dynamic DNS is required to support Active Directory. A dynamic update occurs when a client modifies its corresponding resource record on the DNS server. Dynamic updates occur when: A network connection's IP address is added, deleted, or changed. The DHCP server changes or renews an IP address lease. The client's DNS information is manually changed using ipconfig /registerdns. The client boots. A server is promoted to a domain controller. Dynamic DNS (4:26) Integrating DHCP DDNS Demo

56 Application Layer Protocols
Management Protocols (10:51) Application Protocols (9:36) Work over TCP or UDP plus IP Translate user requests into format readable by network HTTP HTTP is used by Web browsers and Web servers to exchange files (such as Web pages) through the World Wide Web and intranets HTTPS is a secure form of HTTP that uses SSL to encrypt data before it is transmitted. DHCP DHCP is a method for automatically assigning addresses and other configuration parameters to network hosts. Understanding HTTP Demo Other Protocols Built on TCP/IP Demo

57 Telnet Terminal emulation protocol Log on to remote hosts
Using TCP/IP protocol suite TCP connection established Keystrokes on user’s machine act like keystrokes on remotely connected machine Often connects two dissimilar systems Can control remote host Drawback Notoriously insecure The Concept of Telnet Demo

58 FTP (File Transfer Protocol)
FTP provides a generic method of transferring files Send and receive files via TCP/IP FTP can transfer both binary and text files, including HTML, to another host Host running FTP server portion Accepts commands from host running FTP client FTP commands Operating system’s command prompt No special client software required FTP hosts allow anonymous logons Secure FTP (SFTP) More secure version of FTP SFTP uses Secure Shell (SSH) to secure data transfers. SSH ensures that SFTP transmissions use encrypted commands and data which prevent data from being transmitted over the network in clear text. Understanding FTP & TFTP Demo SFTP Demo

59 TFTP (Trivial File Transfer Protocol)
Enables file transfers between computers Simpler (more trivial) than FTP TFTP is faster than FTP, but might be subject to file errors TFTP relies on Transport layer UDP Connectionless No error correction and does not guarantee reliable data delivery No ID or password required Security risk No directory browsing allowed Useful to load data, programs on diskless workstation Often used when transferring files such as video, audio, or images

60 NTP (Network Time Protocol)
NTP is used to communicate time synchronization information between systems on a network Depends on UDP Transport layer services Benefits from UDP’s quick, connectionless nature Time sensitive Cannot wait for error checking Time synchronization importance Routing Time-stamped security methods Maintaining accuracy, consistency between multiple storage systems

61 PING (Packet Internet Groper)
Provides verification TCP/IP installed, bound to NIC, configured correctly, communicating with network Host responding Uses ICMP services Send echo request and echo reply messages Determine IP address validity Ping IP address or host name Ping loopback address: Determine if workstation’s TCP/IP services running Ping (5:16)

62 PING (cont’d.) Operating system determines PING command options, switches, syntax Ping Demo Output from successful and unsuccessful PING

63 Summary Protocols define the standards for communication between nodes on a network TCP/IP is most popular protocol suite, because of its low cost, open nature, ability to communicate between dissimilar platforms, and routability TCP provides reliability through checksum, flow control, and sequencing information IP provides information about how and where data should be delivered Every IP address contains two types of information: network and host

64 Summary (continued) Subnetting is implemented to control network traffic and conserve a limited number of IP addresses Dynamic IP address assignment can be achieved using BOOTP or the more sophisticated DHCP A socket is a logical address assigned to a specific process running on a host IPv6 provides several other benefits over IPv4 A domain is a group of hosts that share a domain name and have part of their IP addresses in common DNS is a hierarchical way of tracking domain names and their addresses

65 The End

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