I didn’t have chance to test this with physical machines, but after adding a new network card to a virtual CentOS node in VMWare Workstation 8, the server will not recognize the newly added device. In this post I will show you how to fix this problem.
Firstly, in my VMWare Workstation, I installed a fresh CentOS machine with a single network card, called eth0. Below is the result of the ifconfig command:
[root@server2 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:B3:55:3A
inet addr:192.168.0.106 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:feb3:553a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:81 errors:0 dropped:0 overruns:0 frame:0
TX packets:88 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:9482 (9.2 KiB) TX bytes:11909 (11.6 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Now, let’s the second network card to the server, called eth1 from VMWare. When you type ifconfig in the terminal, the result is still the same:
[root@server2 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:B3:55:3A
inet addr:192.168.0.106 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:feb3:553a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:81 errors:0 dropped:0 overruns:0 frame:0
TX packets:88 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:9482 (9.2 KiB) TX bytes:11909 (11.6 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
In fact, the second network card was successfully added to the server, but you have to use the option -a in order to see it:
[root@server2 ~]# ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:0C:29:B3:55:3A
inet addr:192.168.0.106 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:feb3:553a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:147 errors:0 dropped:0 overruns:0 frame:0
TX packets:134 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:16414 (16.0 KiB) TX bytes:18145 (17.7 KiB)
eth1 Link encap:Ethernet HWaddr 00:0C:29:B3:55:44
BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
To be able to use this new network card, you need to create a configuration file for it, name the file as ifcfg-eth1 in the directory /etc/sysconfig/network-scripts/ with the following contents:
DEVICE=eth1
HWADDR=00:0C:29:B3:55:44
TYPE=Ethernet
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=dhcp
Note that the value for HWADDR must be taken from the command ifconfig -a above. Save and close the file, and restart the network service:
service network restart
Now type ifconfig, without option -a, the eth1 card will show up:
[root@server2 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:B3:55:3A
inet addr:192.168.0.106 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:feb3:553a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:517 errors:0 dropped:0 overruns:0 frame:0
TX packets:452 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:50956 (49.7 KiB) TX bytes:101981 (99.5 KiB)
eth1 Link encap:Ethernet HWaddr 00:0C:29:B3:55:44
inet addr:192.168.0.107 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:feb3:5544/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:10 errors:0 dropped:0 overruns:0 frame:0
TX packets:10 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1756 (1.7 KiB) TX bytes:1236 (1.2 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Note that if you mistype or give the incorrect value for the HWADDR line in the configuration file of eth1 (/etc/sysconfig/network-scripts/ifcfg-eth1), you will see the following error while restarting the network service:
Bringing up interface eth1: Device eth1 has different MAC address than expected, ignoring.
[FAILED]
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