Wise people learn when they can; fools learn when they must - Arthur Wellesley

Thursday 23 February 2017

RHEL6- (8) IP ASSIGN / CHANGE


                 RHEL6- (8) IP ASSIGN/CHANGE

HOW TO ASSIGN/CHANGE THE IP ADDRESS:

[root@rhel6-server ~]# ifconfig -a
eth0      Link encap:Ethernet  HWaddr 00:0C:29:80:4E:36
          inet6 addr: fe80::20c:29ff:fe80:4e36/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:11151 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1039262 (1014.9 KiB)  TX bytes:468 (468.0 b)


Interface “eth0” has no IP. First we will assign an IP to it then we will change it,

We know that the interface config file resides under,

/etc/sysconfig/network-scripts/

[root@rhel6-server network-scripts]# cat ifcfg-eth0
DEVICE=eth0
HWADDR=00:0C:29:80:4E:36
TYPE=Ethernet
UUID=fd01976e-0dfd-4228-a8ad-3a31e481cef5
ONBOOT=no
NM_CONTROLLED=yes
BOOTPROTO=dhcp

We need to edit the file related to corresponding interface.

Here interface is “eth0” and corresponding file is “ifcfg-eth0”

Better to replace this file with any working interface.

[root@rhel6-server network-scripts]# cp ifcfg-eth3 ifcfg-eth0
cp: overwrite `ifcfg-eth0'? y

[root@rhel6-server network-scripts]# vi ifcfg-eth0
DEVICE=eth3
TYPE=Ethernet
UUID=aff36e84-11b8-4d37-8243-79ba0798839f
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=none
HWADDR=00:0C:29:80:4E:54
IPADDR=192.168.110.135
PREFIX=24
GATEWAY=192.168.234.2
DEFROUTE=yes
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
NAME="System eth3"

Now we need to modify the values.

Well, I overwrite the File and now it is asking for UUID…LLL

Ok… no issues. First of all, UUID and NM_CONTROLLED parameters are not required to operate the interface, they can be ignored.
But if you are eager to supply UUID then,

[root@rhel6-server ~]# uuidgen eth0
0efaf760-cf38-4593-bd5f-59e1642cbb0e

[root@rhel6-server network-scripts]# vi ifcfg-eth0
DEVICE=eth0 çChanged
TYPE=Ethernet
UUID=0efaf760-cf38-4593-bd5f-59e1642cbb0e çChanged
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=none
HWADDR=00:0C:29:80:4E:36 çChanged
IPADDR=192.168.110.137 çChanged
PREFIX=24
GATEWAY=192.168.110.1 çChanged
DEFROUTE=yes
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
NAME="System eth0" çChanged

[root@rhel6-server /]# service network restart
Shutting down interface eth0:  Device state: 3 (disconnected)
                                                           [  OK  ]
Shutting down interface eth1:  Device state: 3 (disconnected)
                                                           [  OK  ]
Shutting down interface eth2:  Device state: 3 (disconnected)
                                                           [  OK  ]
Shutting down interface eth3:  Device state: 3 (disconnected)
                                                           [  OK  ]
Shutting down loopback interface:                          [  OK  ]
Bringing up loopback interface:                            [  OK  ]
Bringing up interface eth0:  Active connection state: activated
Active connection path: /org/freedesktop/NetworkManager/ActiveConnection/10
                                                           [  OK  ]
Bringing up interface eth1:  Active connection state: activated
Active connection path: /org/freedesktop/NetworkManager/ActiveConnection/11
                                                           [  OK  ]
Bringing up interface eth2:  Active connection state: activated
Active connection path: /org/freedesktop/NetworkManager/ActiveConnection/12
                                                           [  OK  ]
Bringing up interface eth3:  Active connection state: activated
Active connection path: /org/freedesktop/NetworkManager/ActiveConnection/13
                                                           [  OK  ]

[root@rhel6-server ~]# ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:0C:29:80:4E:36
          inet addr:192.168.110.137  Bcast:192.168.110.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe80:4e36/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:11180 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1042237 (1017.8 KiB)  TX bytes:468 (468.0 b)

Make this entry in to /etc/hosts also,

[root@rhel6-server ~]# cat /etc/hosts
#127.0.0.1   localhost
192.168.234.146 rhel6-server
#192.168.234.147        rhel6-server
192.168.110.135 rhel6-server
192.168.110.137 rhel6-server çç

TEMPORARY CHANGE:

[root@rhel6-server ~]# ifconfig eth0 192.168.234.192 netmask 255.255.255.0 broadcast 192.168.234.255

In the above command, 192.168.234.192 is machine's IP address, 255.255.255.0 is the netmask and 192.168.234.255 is broadcast address.
The ifconfig command does not store these changes permanently. Upon reboot this information is lost.

[root@rhel6-server ~]# ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:0C:29:80:4E:36
          inet addr:192.168.234.192  Bcast:192.168.234.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe80:4e36/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:11344 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1057476 (1.0 MiB)  TX bytes:468 (468.0 b)

Check the changes are effective or not…?

C:\Users\HP>ping 192.168.234.192
Pinging 192.168.234.192 with 32 bytes of data:
Reply from 192.168.234.192: bytes=32 time=88ms TTL=64
Reply from 192.168.234.192: bytes=32 time=2ms TTL=64
Reply from 192.168.234.192: bytes=32 time=2ms TTL=64
Reply from 192.168.234.192: bytes=32 time=2ms TTL=64

Ping statistics for 192.168.234.192:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 2ms, Maximum = 88ms, Average = 23ms

C:\Users\HP>ping 192.168.110.137

Pinging 192.168.110.137 with 32 bytes of data:
Reply from 192.168.110.1: Destination host unreachable.

Ping statistics for 192.168.110.137:
    Packets: Sent = 1, Received = 1, Lost = 0 (0% loss),
Control-C
^C




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