VISVESWARAIAH TECHNOLOGICAL UNIVERSITY, BELGAUM - 590010

3rd sem QIP M.TechTechnical Seminar on: Network Configuration System including Subnets Class A, B & C

ByV Manohar Nelli 5ZA12SPZ06 Under the Guidance of

Prof. Nirmala C R , Ph.D,M.Tech HOD, DEPT. of CS&E, BIET

BAPUJI INSTITUTE OF ENGINEERING AND TECHNOLOGY,DAVANGERE – 577004

POST GRADUATE DEPARTMENT OF COMPUTER SCIENCE & ENGINEERING

Red hat Enterprise Linux, Cent OS, and Fedora provides the following tools to make changes to network configuration such as add new card, assign/change IP address/subnet/gateway, and change DNS server and more.3 ways to configure network are[a] GUI tool - system-config-network[b] Command line text based GUI tool system-config-network-tui[c]Edit configuration files stored in /etc/sysconfig/network-scripts/ directory. This method works with remote server over the ssh based session

Method 1: GUI tool system-config-network

• Open the X terminal Type the following command at shell prompt: $ system-config-network &

• Next, select your Ethernet card (such as eth0 or eth1) and click on the Edit button. You can now setup/modify IP address, netmask, default gateway and other properties.

• You can obtain IP address using DHCP or setup manually. Once IP address assigned, click on Ok button to save the changes. You can activate card by clicking on Activate button.

Method 2: Command line tool system-config-network-tui

Select your Ethernet card such as eth0 or eth1 and hit [Enter] or [F12] special key to configure IP properties for selected NIC:

Method 3: Edit configuration files stored in/etc/sysconfig/network-scripts/ directory

• You need to edit / create files as follows using a text editor such as vi:

# vi /etc/sysconfig/network-scripts/ifcfg-eth0 : First Ethernet card configuration file.

• Edit or modify as follows for static ip configuration:# eth0 - Intel Corporation 82573E Gigabit Ethernet

Controller (Copper) on server1.cyberciti.biz by nixCraft on 10/4/2007

DEVICE=eth0 BOOTPROTO=static DHCPCLASS= HWADDR=00:30:48:56:A6:2E IPADDR=10.10.29.66 NETMASK=255.255.255.192 ONBOOT=yes

Saving and Restoring the Network Configuration

• To save, or export, the network configuration of a system to the file /tmp/network-config, execute the following command as root:

# system-config-network-cmd -e > /tmp/network-config• To restore, or import, the network configuration from the file

created from the previous command, execute the following command as root:

#system-config-network-cmd -i -c -f /tmp/network-config• The -i option means to import the data, the -c option means

to clear the existing configuration prior to importing, and the -f option specifies that the file to import is as follows.

The five classes of IP address

• Class A addresses have seven bits for network IDs and 24 bits for host IDs, allowing up to 126 networks and about 16 million hosts per network.

• Class B addresses have 14 bits for network IDs and 16 bits for host IDs, allowing about 16,000 networks and about 64,000 hosts for each net- work.

• Class C addresses have 21 bits for network IDs and 8 bits for host IDs, allowing about 2 million networks and 254 hosts per network.

• Class D addresses are used for multicast services that allow a host to send information to a group of hosts simultaneously.

• Class E addresses are reserved for experiments.

IP Address ClassesThe IPv4 address space has been structured into several classes. The

value of the first octet of an address determines the class of the network:

Class First Octet Range Default Subnet Mask

Class A 1 - 127 255.0.0.0Class B 128 - 191 255.255.0.0Class C 192 - 223 255.255.255.0Class D 224 - 239 -

Subnet Addressing

Introducing another hierarchical level through subnet addressing

Subnet Addressing

• The basic idea of subnetting is to add another hierarchical level called the "subnet" as shown in previous slide Figure .

• The beauty of the subnet-addressing scheme is that it is oblivious to the network outside the organization.

• That is, a host outside this organization would still see the original address structure with two levels.

• Inside the organization the local network administrator is free to choose any combination of lengths for the subnet and host ID fields.

Example Subnetwork Addressing

Classless Interdomain Routing (CIDR)• Classless Inter-Domain Routing (CIDR) is a simplified method of

representing a subnet mask. CIDR identifies the number of binary bits set to a 1 (or on) in a subnet mask, preceded by a slash.

• For example, a subnet mask of 255.255.255.240 would be represented as follows in binary: 11111111.11111111.11111111.11110000

• The first 28 bits of the above subnet mask are set to 1. The CIDR notation for this subnet mask would thus be /28.

• The CIDR mask is often appended to the IP address. For example, an IP address of 192.168.1.1 and a subnet mask of 255.255.255.0 would be represented as follows using CIDR notation: 192.168.1.1 /24

instead of having four entries for a contiguous set of Class C addresses (e.g., 205.100.0.0, 205.100.1.0, 205.100.2.0, and 205.100.3.0), CIDR allows a single

entry 205.100.16.0/22. The structure of it is,

205.100.0.0=11001101.01100100.00000000.00000000 205.100.1.0=11001101.01100100.00000001.00000000

205.100.2.0=11001101.01100100.00000010.00000000 205.100.3.0=11001101.01100100.00000011.00000000

mask=11111111.11111111.11111100.00000000Common subnet number when ip bitwise anded with mask

255.255.252.0 is 205.100.0.0

THANK YOU