Basic Network Configuration:
Networks are two types
1. IPv4
2. IPv6
What is IP Address :
Every computer on network requires an IP address to communicate with other computer. Linux is developed for networking. To pass RHCE exam you must understand networking.
An IP is a 32-bit number comprised of a host number and a network prefix, both of which are used to uniquely identify each node within a network.
To make these addresses more readable, they are broken up into 4 bytes, or octets, where any 2 bytes are separated by a period. This is commonly referred to as dotted decimal notation.
The first part of an Internet address identifies the network on which the host resides, while the second part identifies the particular host on the given network. This creates the two-level addressing hierarchy.
All hosts on a given network share the same network prefix but must have a unique host number. Similarly, any two hosts on different networks must have different network prefixes but may have the same host number.
Here is a simple example of an IP address: 192.168.1.1
An additional value, called a subnet mask, determines the boundary between the network and host components of an address.
Subnet masks are 32 bits long and are typically represented in dotted-decimal (such as 255.255.255.0) or the number of networking bits (such as /24). The networking bits in a mask must be contiguous and the host bits in the subnet mask must be contiguous. 255.0.255.0 is an invalid mask. A subnet mask is used to mask a portion of the IP address, so that TCP/IP can tell the difference between the network ID and the host ID. TCP/IP uses the subnet mask to determine whether the destination is on a local or remote network.
Stages of IP Address :
Assign IP Address in Linux : (RHEL 6)
To set up a network we need following parameters
1. IP Address
2. Subnet Mask
3. Gateway
4. DNS Server
In RHEL you can assign these parameters in two ways.
To use static IP configuration press TAB key to highlight DHCP option and press SPACEBAR to deselect it. Fill necessary parameters and select Ok by pressing TAB key. Once OK is highlighted press ENTER
Select Save by pressing TAB key and press ENTER
Select Save & Quit by pressing TAB key and press ENTER
To put the configuration customized with this tool into effect we need to reactivate the associated device. Until we reactivate associated device it would run with old configuration. You can check it with ifconfig command.
Use ifdown command to deactivate and ifup to activate.
Check again with ifconfig command. The configuration of the network card should reflect the new configuration.
Now enter all the fields like BOOTPROTO, IPADDR, NETMASK, ONBOOT etc
and then save the file and close
Setting Default Gateway and Hostname :
To change the hostname use the following command
To assign default gateway and hostname we need to define them in the /etc/sysconfig/network file
Then modify the below fields
Add the DNS server ip addresses to the /etc/resolv.conf filw
Save and close the file.
After completing all these setup test it whether it is correctly configured or not
Networks are two types
1. IPv4
2. IPv6
What is IP Address :
Every computer on network requires an IP address to communicate with other computer. Linux is developed for networking. To pass RHCE exam you must understand networking.
An IP is a 32-bit number comprised of a host number and a network prefix, both of which are used to uniquely identify each node within a network.
To make these addresses more readable, they are broken up into 4 bytes, or octets, where any 2 bytes are separated by a period. This is commonly referred to as dotted decimal notation.
The first part of an Internet address identifies the network on which the host resides, while the second part identifies the particular host on the given network. This creates the two-level addressing hierarchy.
All hosts on a given network share the same network prefix but must have a unique host number. Similarly, any two hosts on different networks must have different network prefixes but may have the same host number.
Here is a simple example of an IP address: 192.168.1.1
An additional value, called a subnet mask, determines the boundary between the network and host components of an address.
Subnet masks are 32 bits long and are typically represented in dotted-decimal (such as 255.255.255.0) or the number of networking bits (such as /24). The networking bits in a mask must be contiguous and the host bits in the subnet mask must be contiguous. 255.0.255.0 is an invalid mask. A subnet mask is used to mask a portion of the IP address, so that TCP/IP can tell the difference between the network ID and the host ID. TCP/IP uses the subnet mask to determine whether the destination is on a local or remote network.
Class A addresses range from 1-126
Class B addresses range from 128-191
Class C addresses range from 192-223
Class D addresses range from 224-239
Class E addresses range from 240-254
0 is reserved and represents all IP addresses;
127 is a reserved address and is used for loop back tasting:
255 is a reserved address and is used for broadcasting purposes.
Assign IP Address in Linux : (RHEL 6)
To set up a network we need following parameters
1. IP Address
2. Subnet Mask
3. Gateway
4. DNS Server
In RHEL you can assign these parameters in two ways.
1. Static configuration
2. Dynamic configuration
Static configuration :
In static configuration you have to assign all these parameters manually. Static configuration does not change automatically. Static configuration generally used with servers or network resources like printer, router etc. Static configuration uses set parameters for the configuration, which is known by the system and the network.
Dynamic configuration :
Dynamic configurations are handled by DHCP server. In dynamic configuration DHCP service on the network provides all these parameters to a system when it joins the network.
Dynamic configuration generally used with workstations. Dynamic configuration configures network parameters on the boot.
Red Hat provides two tools to configure the network device.
We can Assign IP Address to a system through
Command Line : (Semi Graphical)
This is a command line network configuration tool. Use this tool to configure IP address on console. This tool can be invoked by running system-config-network command.
Network Manager Window is opened. Now press Enter to Go to the Options
On Select A Device screen select first network card (eth0) and press ENTER
Now we are on Network configuration screen. As we mentions above IP configuration can be set in two ways static or dynamic.
To set IP configuration dynamically Select DHCP
2. Dynamic configuration
Static configuration :
In static configuration you have to assign all these parameters manually. Static configuration does not change automatically. Static configuration generally used with servers or network resources like printer, router etc. Static configuration uses set parameters for the configuration, which is known by the system and the network.
Dynamic configuration :
Dynamic configurations are handled by DHCP server. In dynamic configuration DHCP service on the network provides all these parameters to a system when it joins the network.
Dynamic configuration generally used with workstations. Dynamic configuration configures network parameters on the boot.
Red Hat provides two tools to configure the network device.
We can Assign IP Address to a system through
1. Command Line
2. Editing Configuration Files
Command Line : (Semi Graphical)
This is a command line network configuration tool. Use this tool to configure IP address on console. This tool can be invoked by running system-config-network command.
#system-config-network Now we are on Network configuration screen. As we mentions above IP configuration can be set in two ways static or dynamic.
To set IP configuration dynamically Select DHCP
To put the configuration customized with this tool into effect we need to reactivate the associated device. Until we reactivate associated device it would run with old configuration. You can check it with ifconfig command.
Editing Configuration Files :
We can configure network settings by editing the configuration files stored in /etc/sysconfig/network-scripts
# vi /etc/sysconfig/network-scripts/ifcfg-eth0
Now enter all the fields like BOOTPROTO, IPADDR, NETMASK, ONBOOT etc
# 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
and then save the file and close
Setting Default Gateway and Hostname :
You can set the hostname in the command line also.
To see the hostname use the following command
To see the hostname use the following command
#hostname
To change the hostname use the following command
#hostname myserver To assign default gateway and hostname we need to define them in the /etc/sysconfig/network file
#vi /etc/sysconfig/network
Then modify the below fields
NETWORKING=yes
HOSTNAME=localhost.localadmin
GATEWAY=10.10.29.65
Save the File. Finally you need to restart the network service with the below command
# /etc/init.d/network restart
Setting DNS Server :
Edit DNS Server details in /etc/resolv.conf file
#vi /etc/resolv.conf
Add the DNS server ip addresses to the /etc/resolv.conf filw
nameserver 127.2.52.80
nameserver 10.52.78.54
nameserver 198.0.2.45
Save and close the file.
After completing all these setup test it whether it is correctly configured or not
# ping 127.2.52.80
Output Will be like below
PING 127.2.52.80 (127.2.52.80) 56(84) bytes of data.
64 bytes from 127.2.52.80: icmp_seq=1 ttl=251 time=0.972 ms
64 bytes from 127.2.52.80: icmp_seq=2 ttl=251 time=1.11 ms
0 comments: