Question : step by step network configuration in Linux ?
Question : step by step host configuration in centos ?
Question : how to configure a virtual network card in Linux ?
Question : step by step ip configuration in Linux ?
Question : how to disable and enable a LAN or Ethernet card in Linux centos ?
Network Configuration
In the Network Configuration: we will configure HOSTNAME, IP Address, DNS , routing
Related configuration file
- /etc/Resolve.conf
- /etc/hosts
- /etc/sysconfig/network
- /etc/sysconfig/network-scripts/ifcfg-<device>
- /etc/nsswitch.conf
1. resolve.conf - its content a DNS record / List of DNS server
# vi /etc/resolve.conf
It's responsible for Primary , Secondary & thirty dns record
#format
search local.lan
NameserverX.X.X.X
NameserverX.X.X.X
2 hosts - it s content a host name , to be resolve by locally.
#Vi /etc/hosts
#format
<IP Address> <hostname.domainname> <hostname>
10.20.2.33 khandwa.lokesh.com khandwa
3 network - set hostname permanently & networking
#Vi /etc/sysconfig/network
#format
NETWORKING =yes
HOSTNAME=lokesh
4 fcfg-<device> - it s content IP address, h/w id etc,
# vi /etc/sysconfig/network-scripts/ifcfg-eth0
#format
DEVICE=eth0 -----------------Device: first etharnet called eth0
NM_CONTROLLED=no ----- Network Manager controlled
HWADDR=00:1e:8c:9c:10:95 - hardware Address
ONBOOT=yes ------------------ up on system reboot
TYPE=Ethernet -------------- Ethernet
USERCTL=no
IPV6INIT=no ---------------------- IP Address v6
IPADDR=10.20.2.33 ---------------- IP Address v4
NETMASK=255.255.255.0 ----------- Mask
GUI Command - set all network related configuration by following command, it s a graphical and easy tool.
# system-config-network
Here you can set ip address & DNS configuration.
To Start network Service
# service network restart
To Stop network service
# service network restart
5 nsswitch.conf : list order of host name search. Typically lok at local files, then NIS server
IP Configuration by command line
ifconfig:- it's used to configure, or view the configuration of, a network interface. It stands for "interface configuration". It is used to view and change the configuration of the network interfaces on your system.
# ifconfig
To view all interface
# ifconfig -a
To view specific interface
# ifconfig eth0
To enable interface
# ifconfig eth0 up
OR
#ifup eth0
To disable interface
# ifconfig eth0 down
OR
#ifdown eth0
Assign the IP address,netmask & broadcast , you can use separate
# ifconfig <device> < IP Address> netmask <netmask> broadcast < Broadcast>
# ifconfig eth0:2 10.20.2.35 netmask 255.255.255.0 broadcast 10.20.2.255
Here eth0.2 is virtual Ethernet card / alias of Ethernet card
To disable alias
# ifconfig eth0:2 down
How to enable promiscuous Mode:
What happens in normal mode, when a packet received by a network card, it verifies that the packet belongs to itself. If not, it drops the packet normally, but in the promiscuous mode is used to accept all the packets that flow through the network card.
# ifconfig eth0 promisc
How to disable promiscuous Mode: add - for disable
# ifconfig eth0 -promisc
How to change MAC Address:
# ifconfig eth0 hw ether AA:BB:CC:DD:EE:FF
Create Virtual Network card: permanent
[root@khandwa ~]# cd /etc/sysconfig/network-scripts/
[root@khandwa network-scripts]# cp ifcfg-eth0 ifcfg-eth0.1
Open ifcfg-eth0:1 file and set ip address
Here ip - 10.20.2.34
Now restart network service
#service network restart
