CPMT 1449 Computer Networking Technology – Lesson 3 CPMT 1449 Computer Networking Technology – Lesson 3.2-Chapter 10 In-Depth TCP/IP Networking

Learning Objectives Understand methods of networking design unique to TCP/IP networks, including subnetting, CIDR, and address translation Explain the differences between public and private TCP/IP networks Describe the protocols used between mail clients and mail servers, including SMTP, POP3, IMAP4 Employ multiple TCP/IP utilities for network discovery and troubleshooting

Subnetting Subnetting is segmenting networks There are several reasons to subnet a network Enhanced security Improve performance Simplify troubleshooting Conserving IP address blocks

Classful Addressing in IPv4 Adheres to network class distinctions An IPv4 address is divided into 2 portions Network Host Class A has 8 bits or 1 octet as the network portion and 3 octets for the host portion Class A network address 10.56.204.33 Network portion = 10 Host portion = .56.204.33 Class B has 16 bits or 2 octets as the network portion and 2 octets for the host portion Class B network address 147.12.38.81 Network portion = 147.12 Host portion = .38.81 Class C has 24 bits or 3 octets as the network portion and 1 octet for the host portion Class C network address 192.168.5.120 Network portion = 192.168.5 Host portion = .5

Address Classes and Default Subnet Masks

Classless Inter-Domain Routing (CIDR) Conventional network class distinctions do not exist In classful routing a Class C can be divided into 6 subnets with 30 available hosts This is achieved by moving the subnet boundary to the right In CIDR the boundary can also be moved to the left Also called supernetting

Calculating and Subnetting IPv4 Subnets Class A Address 10. 168. 74. 232………IP address 240 0 0………….Subnet Mask The parts of the IP address that are above a zero of the mask we don’t have to worry about when we want to find the subnet address. So the only part we have left to work out is the 168 part over the 240 part of the mask. The magic number is 256 so 256-240 = 16 So we now know that these subnets are in blocks of 16 Now we can find out the start of this subnet Take the 168 part of the IP address and divide it by the answer 16 we got above. 168 divided by 16 = 10.5 Take the whole number of the above = 10 Multiply that 10 by 16 (10 x 16 = 160) We now know that this subnet starts at 160 = 10.160.0.0 Our original IP Address: 10.168.74.232 10.160.0.0 The subnet the above IP address lies in 10.160.0.1 First IP address 10.175.255.254 Last IP address 10.175.255.255 Broadcast address 10.176.0.0 160+16 = Next subnet

Which subnet does host 172.168.74.232/20 belong to ? If part of the IP address is above a zero on the mask then we don’t need to do anything it 172. 168. 74. 232 255 240 0 The magic number is 256 so 256-240 = 16 So we now know that these subnets are in blocks of 16 Take the 74 part of the IP address and divide it by the answer 16 we got above. Take the 74 and divide it by 16 = 4.625 Take the whole number of the above = 4 Multiply that 4 by 16 = 64 We now know that this subnet starts at 64 = 172.168.64.0 The range of this is 172.168.64.0 Subnet the above IP address lies in 172.168.64.1 First IP address 172.168.79.254 Last IP address = 1 less than the broadcast 172.168.79.255 Broadcast address = 1 less than the next subnet 172.168.80.0 64+16 = Next subnet Class B Address

What subnet does host 192.168.74.232/28 belong to ? Put the IP address above the mask 192. 168. 74. 232 255 255 255 240 The magic number is 256 so 256 – 240 (Last part of the mask) = 16 This means that in every subnet we have 16 IP addresses. Now to find out the subnet the 232 part of the IP address is in, divide this 232 by our last answer of 16, so: 232 divided by 16 = 14.5 Now take the whole number of our last answer = 14 and multiply this by 16 to give you the start of the subnet. 14 x 16 = 224 So the answer to the question “which subnet does host 192.168.74.232/28 belong to. = 192.168.74.224 Class C Address

Gateways The first interface that interprets all outbound and inbound traffic for network or subnetwork Every node has a default-gateway, but only one default-gateway Either configured manually or automatically (DHCP)

Address Translation Public network – any user can access with little or no restrictions Private network – restricted to clients or nodes with proper authorization Clients behind a gateway can us any IP address scheme – legitimate or not Clients that connect to the Internet must have a legitimate IP address Network Address Translation (NAT) When the user’s data reaches the gateway, the gateway replace the private IP address with a legitimate address Overcomes low quantity of IPv4 addresses

Three Types of NAT Static Network Address Translation (SNAT) Dynamic Network Address Translation (DNAT) Port Address Translation (PAT) (Use graphic)

TCP/IP Mail Services Simple Mail Transfer Protocol (SMTP) – Responsible for moving messages from one server to another Multipurpose Internet Mail Extensions (MIME) – A standard for encoding and interpreting binary files, images, video, and non-ASCII character sets within an email message Post Office Protocol/version 3 (POP/POP3) - Application Layer protocol that is used to retrieve messages from a mail server – POP3 uses TCP and uses port 110 Internet Message Access Protocol/version 4 (IMAP/IMAP4) – Mail retrieval protocol that was supposed to replace POP3

Additional TCP/IP Utilities – Windows, UNIX, Linux OS’s ipconfig – TCP/IP administration utility for use with Windows NT, 2000, XP, Vista, Sever 2003, and Server 2008 Oss. ifconfig – TCP/IP administration utility for use with UNIX and Linux OSs netstat – Utility that displays TCP/IP statistics, and details about TCP/IP components and connections nbstat – Utility that provides information about NetBIOS statistics and resolve names to their IP addresses hostname – Command that allows a client to see the hostname assigned host – Utility used to find the IP address of a known hostname

Additional TCP/IP Utilities – Windows, UNIX, Linux OS’s nslookup – Allows the user to query the DNS database from any node on the network dig – domain information groper – Similar to nslookup. Allows the user to query DNS servere for DNS information whois – Allows you to query the DNS registration database and get information about a domain tracert – uses ICMP ECHO request to trace the path form one node to another mtr – Used by UNIX or Linux OSs is a route discovery utility route – Used on UNIX and Linux systems to view a host’s routing table

End of Presentation For more information on this lesson, See Chapter 10 in the text book or email the Professor **All Slides and graphics were produced by Professor Patrick Hughes**