Network Configuration

Network Configuration.

IP Addressing

An IP address is a numeric identifier assigned to each machine on an IP network. It designates the specific location of a device on the network.

We can assign IP Address to computer by using two methods

1.     Static [ Manually ]

2.     Dynamic [ Using DHCP Server ]

There are three methods for depicting IP Addresses

1. Dotted Decimal   :- 10.2.11.10

2. Binary :- 00001010.00000010.00001011.00001010

3. Hexa-Decimal :- A.2.B.A 

 

IP Address Classes :-

Classes        IP Range      Octet        Network ID / Host ID 

Class A        0-127          8.8.8.8       N.H.H.H

Class B        128-191      8.8.8.8       N.N.H.H

Class C192-223              8.8.8.8       N.N.N.H

Class D        224-239      8.8.8.8       N.N.N.N

Class E240-255              8.8.8.8       N.N.N.N

1. To view IP Address.

[root@server1 ~]#ifconfig      

2. To set IP Address.

[root@server1 ~]#setup                      

1. Under Choose a Tool Dialog Box select Network configuration and press ENTER

2. Under Select Action Dialog Box select Device configuration and press ENTER

3. Under Select A Device Dialog Box select eth0 (eth0) – Ethernet and press ENTER

4. Under Network Configuration Dialog Box add following entries

Name                           eth0

Device                         eth0

Use DHCP                  [*]                               

Static IP                                                           This setting is applicable if DHCP server is    

Netmask                                                          configured and machine will get IP from it

Default gateway IP                                         or else you need to set static IP for a machine

Primary DNS Server 

Secondary DNS Server

Name                           eth0

Device                         eth0

Use DHCP                  []                                          to uncheck * press spacebar and set static IP.             

Static IP                      10.0.0.1                                   for a machine use this settings.           

Netmask                      255.0.0.0                                

Default gateway IP

Primary DNS Server 

Secondary DNS Server

Select on Ok and press ENTER.

5. Select Save and press ENTER.

6. Select Save&Quit and press ENTER

7. SelectQuit and press ENTER

[root@server1 ~]#ifconfig                                          

[root@server1 ~]#service network restart                   

[root@server1 ~]#ping  10.0.0.1                               

3. To add another Ethernet id and set IP for it.

[root@server1 ~]#setup                                              

1. Under Choose a Tool Dialog Box select Network configuration and press ENTER

2. Under Select Action Dialog Box select Device configuration and press ENTER

3. Under Select A Device Dialog Box select and press ENTER

4. Under Network Configuration select Ethernet and press ENTER or select ADD

Now set Ethernet device name and IP address

Name                           eth1

Device                         eth1

Use DHCP                  []                                  to uncheck * press spacebar and set static IP.             

Static IP                      10.0.0.10                     for a machine use this settings.           

Netmask                      255.0.0.0                                

Default gateway IP

Primary DNS Server 

Select on Ok and press ENTER.

5. Select Save and press ENTER.

6. Select Save&Quit and press ENTER

7. SelectQuit and press ENTER

[root@server1 ~]#ifconfig                                         

[root@server1 ~]#service network restart                    

[root@server1 ~]#ping  10.0.0.1                                 

3. To view network configuration file.

[root@server1 ~]#cat  /etc/sysconfig/network-scripts/ifcfg-eth0                   

DEVICE=eth0

NM_CONTROLLED=yes

ONBOOT=yes

IPADDR=10.0.0.1

BOOTPROTO=none

NETMASK=255.0.0.0

TYPE=Ethernet

IPV6INIT=no

USERCTL=no

HWADDR=00:0C:29:E4:E8:D4

PREFIX=8

DEFROUTE=yes

IPV4_FAILURE_FATAL=yes

NAME=”System eth0”

UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03

4. To change hostname of a computer using file.

[root@server1 ~]#cat  /etc/sysconfig/network                         

NETWORKING=yes

HOSTNAME=server1

5. To change IP address temporary.

[root@server1 ~]#ifconfig                                                       

eth2     inet addr : 100.0.0.1 Bcast: 100.255.255.255  Mask: 255.0.0.0

[root@server1 ~]#ifconfig  eth2  20.0.0.1                             

[root@server1 ~]#ifconfig                                                      

eth2     inet addr : 20.0.0.1 Bcast: 20.255.255.255  Mask: 255.0.0.0

[root@server1 ~]#service network restart                         

[root@server1 ~]#ifconfig                                                           

eth2     inet addr : 100.0.0.1 Bcast: 100.255.255.255  Mask: 255.0.0.0                       

                                                                                                                               

5. To create temporary alternate IP address .         

[root@server1 ~]#ifconfig                                                       

eth2     inet addr : 100.0.0.1 Bcast: 100.255.255.255  Mask: 255.0.0.0

[root@server1 ~]#ifconfig  eth2:0  20.0.0.1      

[root@server1 ~]#ifconfig                                 

eth2:0    inet addr : 20.0.0.1 Bcast: 20.255.255.255  Mask: 255.0.0.0

[root@server1 ~]#service network restart      

[root@server1 ~]#ifconfig                            

6. To create permanent alternate IP address temporary.

[root@server1 ~]#cd  /etc/sysconfig/network-scripts             

[root@server1 network-scripts]#vi  ifcfg-eth2:0

DEVICE=eth0:0

ONBOOT=yes

IPADDR=200.0.0.1

BOOTPROTO=static

NETMASK=255.0.0.0

TYPE=Ethernet

NM_CONTROLLED=no

:wq!

[root@server1 network-scripts]#service network restart         

[root@server1 network-scripts]#ifconfig                                

Note:- Whenever you assign temporary ip address or temporary lan card after you restart the network services the temporary settings will disappear.