[SOLVED] eth0 is not displayed in ifconfig

fairladyz · 01-07-2013, 06:52 AM

hi guys,
i actually new to centos,

ifconfig doesn't display eth0 just like below:

Code:

[root@fairladyz ~]# ifconfig
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:552 errors:0 dropped:0 overruns:0 frame:0
          TX packets:552 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:33480 (32.6 KiB)  TX bytes:33480 (32.6 KiB)

p1p1      Link encap:Ethernet  HWaddr 00:1C:23:29:E2:51  
          inet addr:192.168.1.10  Bcast:192.168.1.255  Mask:255.255.255.0
          UP 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)
          Interrupt:17 

wlan0     Link encap:Ethernet  HWaddr 00:1F:3B:73:52:6F  
          inet addr:192.168.43.116  Bcast:192.168.43.255  Mask:255.255.255.0
          inet6 addr: fe80::21f:3bff:fe73:526f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:23687 errors:0 dropped:0 overruns:0 frame:0
          TX packets:24443 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:17051939 (16.2 MiB)  TX bytes:4655176 (4.4 MiB)

i already tried to do /etc/udev/rules.d/70-persistent-net.rules it showed:

Code:

[root@fairladyz ~]# cat /etc/udev/rules.d/70-persistent-net.rules
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:1f:3b:73:52:6f", ATTR{type}=="1", KERNEL=="wlan*", NAME="wlan0"

only wlan0 that showed up, then i tried to do dmesg | grep eth0, it showed:

Code:

[root@fairladyz ~]# dmesg | grep eth0
sky2 eth0: addr 00:1c:23:29:e2:51
udev: renamed network interface eth0 to p1p1

eth0 has renamed to p1p1. i kind of don't understand.

my laptop manufactured by dell.i'm using windows and centos.
in windows i can connect wired network without anything wrong.

please help me ;(.
thanks before.

MensaWater · 01-07-2013, 07:29 AM

I'm assuming this is CentOS 6.1 or higher?

CentOS is a binary compile from RHEL (RedHat Enterprise Linux) source. With RHEL 6.1 RedHat introduced use of biosdev on supported systems to make network device names relative to their physical location in the system rather than simply being numbered from eth0 to ethn. Dell is one of the vendors that provides this biosdev information. The theory is that your system might decide what is eth0 today is eth1 tomorrow while what was eth3 is now eth0. With the specific names you don't have this issue as the name for a given NIC will always be the same so long as it is always in the same physical location in the system.

This article at Dell's site gives more detail including how to disable biosdev if you want to use the old method:

Quote:

Red Hat Enterprise Linux 6 Update 1 (RHEL 6.1) that is now available from Red Hat implements a new naming convention for network interfaces. The ‘biosdevname’ udev helper utility, developed by Dell and released under GPL, suuggests new names to network interfaces based on their physical location in the system.

On installing RHEL 6.1 on supported Dell PowerEdge servers the new network interface names will be:

emN (em1, em2, ..)

instead of traditional ethN names for Lan-On-Motherboard interfaces.

For PCI add-in network interfaces the names will be:

pXpY (p<slot number>p<port number> - p1p1, p1p2, ..).

With the new naming scheme, em1 will map to ‘Gb1’ (em2 to ‘Gb2’) as labeled on server chassis, making effective administration of network interfaces easier. The p1p2 names make it easier to identify network ports on add-on cards.

The new naming scheme is turned-on by default on supported Dell PowerEdge platforms. The new naming scheme can be disabled by passing ‘biosdevname=0’ kernel command line parameter during install time and retaining it through runtime.

Existing scripts that have ethN names hardcoded might require change to make them network device name agnostic.

Please refer to this document for more information on the new naming convention on supported Dell PowerEdge Servers.

LeoPap · 01-08-2013, 03:45 PM

i had the same problem when i first install centos.

try writing : ifdown eth0 and then ifup eth0

and retry ifconfig -a

MensaWater · 01-08-2013, 05:26 PM

Quote:

Originally Posted by LeoPap

i had the same problem when i first install centos.

try writing : ifdown eth0 and then ifup eth0

and retry ifconfig -a

The OP's post shows that udev is renaming eth0 to p1p1 so this wouldn't work unless he turns off biosdev stuff as I mentioned. He doesn't need to turn off biosdev though for most purposes p1p1 would work just as well as eth0 - it is just a name and gives more detail than eth0 does in the name.

fairladyz · 01-09-2013, 08:31 AM

Quote:

Originally Posted by LeoPap

i had the same problem when i first install centos.

try writing : ifdown eth0 and then ifup eth0

and retry ifconfig -a

i've tried and it won't work just like mensaWater said,

so it's only matter of name??
i have read an article that some distro can only recognize eth*.

if things goes like that then so be it...

LeoPap · 01-09-2013, 08:43 AM

Here is a mini tutorial (7 steps) how you can rename the p1p1 to eth*.

Of course it is for ubuntu, but i don't think that you will face any problem.

suicidaleggroll · 01-09-2013, 08:45 AM

Quote:

Originally Posted by fairladyz

i've tried and it won't work just like mensaWater said,

so it's only matter of name??
i have read an article that some distro can only recognize eth*.

if things goes like that then so be it...

You don't have an eth0 because your distro didn't name your ethernet port eth0, it named it p1p1. p1p1 is your ethernet port, you will never have an "eth0" unless you disable biosdev. Usually this won't be a problem, but SOME applications do require an eth0 for licensing (to get your mac address). That's something you can deal with when the time comes though.

LeoPap · 01-09-2013, 08:50 AM

Quote:

Originally Posted by suicidaleggroll

You don't have an eth0 because your distro didn't name your ethernet port eth0, it named it p1p1. p1p1 is your ethernet port, you will never have an "eth0" unless you disable biosdev. Usually this won't be a problem, but SOME applications do require an eth0 for licensing (to get your mac address). That's something you can deal with when the time comes though.

Exactly what the above says. It is doesn't bother you, then leave it that way. Of course remember that some software require the name eth* and nothing else. Also some other require the name p1p1 only, Matlab for example!

fairladyz · 01-09-2013, 09:01 AM

I see now,

actually i haven't try wired network though,
i always use tethering in my home to get connected.

well at least, i got a lot of things to know.
thanks anyway

Quote:

Usually this won't be a problem, but SOME applications do require an eth0 for licensing (to get your mac address). That's something you can deal with when the time comes though

I prefer to avoid this,