CentOS Networking FAQ

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How to set static ip..?

[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=static
IPADDR=192.168.1.13
NETMASK=255.255.255.0
TYPE=Ethernet
[root@localhost ~]#

Edit your /etc/sysconfig/network-scripts/ifcfg-eth0 file like this. Then restart your network.

How to restart the network..?

The command for stop the network is /etc/init.d/network stop

To start the network /etc/init.d/network start

OR

[root@localhost ~]# /etc/init.d/network restart
Shutting down interface eth0:                              [  OK  ]
Shutting down loopback interface:                          [  OK  ]
Bringing up loopback interface:                            [  OK  ]
Bringing up interface eth0:                                [  OK  ]
[root@localhost ~]#

How to stop and start the firewall..?

To stop /etc/init.d/iptables stop

To start /etc/init.d/iptables start

OR

[root@localhost ~]# /etc/init.d/iptables restart
Flushing firewall rules:                                   [  OK  ]
Setting chains to policy ACCEPT: filter                    [  OK  ]
Unloading iptables modules:                                [  OK  ]
Applying iptables firewall rules:                          [  OK  ]
Loading additional iptables modules: ip_conntrack_netbios_n[  OK ]
[root@localhost ~]#

How to view my networking information..?

command for to view all the networking info "ifconfig"

[root@localhost ~]# ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:16:3E:A0:00:06
inet addr:192.168.1.13  Bcast:192.168.1.255  Mask:255.255.255.0
inet6 addr: fe80::216:3eff:fea0:6/64 Scope:Link
UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
RX packets:1046 errors:0 dropped:0 overruns:0 frame:0
TX packets:297 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:81732 (79.8 KiB)  TX bytes:37712 (36.8 KiB)
Interrupt:5 Base address:0x2000
[root@localhost ~]#

How to add nameserver..?

Add your nameserver (dns) /etc/resolv.conf like this.Here Airtel dns ip is used.

[root@localhost ~]# cat /etc/resolv.conf
; generated by /sbin/dhclient-script
nameserver 203.145.184.13
search localdomain
[root@localhost ~]#

How to add Gateway and Hostname..?

open the file /etc/sysconfig/network. Then add your gateway ip. For the hostname change the HOSTNAME line by default this line is localhost.localdomain. Then restart your network.

[root@localhost ~]# cat /etc/sysconfig/network
NETWORKING=yes
NETWORKING_IPV6=no
HOSTNAME=yourdomain.com
GATEWAY=192.168.1.1
[root@localhost ~]#

OR

route add -net 0.0.0.0 gw 192.168.1.1

How to add a service..?

Copy your service shell script file to /etc/init.d folder. To add a service.

[root@localhost ~]# chkconfig -- add servicename

To startup the service at the boot time.

[root@localhost ~]# chkconfig --level 5 servicename on

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