CentOS 6.9 in DELL M4600 - not "networking"

Issues related to configuring your network
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T430s
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Joined: 2017/06/02 15:48:49

CentOS 6.9 in DELL M4600 - not "networking"

Post by T430s » 2017/06/02 16:34:42

I installed CentOS 6.9 ("basic server") in a Dell Precision M4600 laptop, but I could not make networking work, so I decided to ask in this forum.

The laptop has two NICs, one wired LAN and teh other wireless LAN.
I am trying to configure network connection using the wired NIC.
The MAC below ( ifcfg-em1) belongs to the wired NIC.

This is in my ifcfg-em1:
//-------------------------------------------

Code: Select all

DEVICE=em1
TYPE=Ethernet
UUID=dccc43e9-432b-4fc9-9c00-dd797d4cbb6a
ONBOOT=yes
NM_CONTROLLED=no
BOOTPROTO=none
IPADDR=a_static_ip
PREFIX=24
GATEWAY=some_appropriate_address
DEFROUTE=yes
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
NAME="System em1"
HWADDR=D0:67:E5:30:91:E4
The problem is that my 70-persistent-net.rules has entry for the wireless NIC only.
Like this:
# PCI device 0x8086:0x422b (iwlwifi) (custom name provided by external tool)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:24:d7:e1:37:80", ATTR{type}=="1", KERNEL=="wlan*", NAME="wlan0"

Question:
How can I have the entry for the wired NIC (NAME = EM1) inside the 70-persistent-net.rules file?

My solution:
I edited KERNEL=="wlan*", NAME="wlan0" like this:
KERNEL=="em*", NAME="em1".

When I reboot (by the way, do I need to reboot when I change contents of 1. ifcfg-em1, 2.70-persistent-net.rules?), I now get two entries, like this:

Code: Select all

#1
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="D0:67:E5:30:91:E4", 
ATTR{type}=="1", KERNEL=="em*", NAME="em1"

#2 
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:24:d7:e1:37:80", 
ATTR{type}=="1", KERNEL=="wlan*", NAME="wlan0"
(I edited ATTR{address}, to reflect the MAC address of the wired LAN ("em1")

I still cannot connect to the outside world.
Could someone please give me some suggestion?

Thank you.

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TrevorH
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Re: CentOS 6.9 in DELL M4600 - not "networking"

Post by TrevorH » 2017/06/02 16:51:42

Do you see your em1 interface listed if you run ifconfig -a ? Are you 100% sure that you have specified the correct ip address, netmask and gateway address? If both interfaces are coming up, make sure that only one of them contains a GATEWAY= line or they will fight with each as to who defines the default route.
CentOS 6 will die in November 2020 - migrate sooner rather than later!
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 is dead, do not use it.
Full time Geek, part time moderator. Use the FAQ Luke

T430s
Posts: 3
Joined: 2017/06/02 15:48:49

Re: CentOS 6.9 in DELL M4600 - not "networking"

Post by T430s » 2017/06/05 05:35:15

TrevorH, thank you for your message.

Yes, ifconfig -a shows ema1 and lo. (I have disabled wlan now.)
I did not have entries for NETMASK and DNS, now I have added NETMASK, DNS1 and DNS2.
The netmask given to me was 255.255.252.0.

Adding NETMASK and DNS brought me a step closer.
After adding the above entries, I noticed the output of ifconfig -a contained Mask:255.255.255.0.
The netmask given to me was 252 in the 3rd octet, so thought PREFIX=24 may be the culprit. (PREFIX=24 was there from the beginning.)

I commented out PREFIX=24, and restarted the network (service network restart), and now I can access the internet.

Now my ifcfg-em1 contains this:

Code: Select all

DEVICE=em1
TYPE=Ethernet
UUID=dccc43e9-432b-4fc9-9c00-dd797d4cbb6a
ONBOOT=yes
NM_CONTROLLED=no
BOOTPROTO=none
IPADDR=static_ip
#PREFIX=24
GATEWAY=some_appropriate_address
NETMASK=255.255.252.0
DNS1=some_appropriate_address
DNS2=some_appropriate_address

DEFROUTE=yes
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
NAME="System em1"
HWADDR=D0:67:E5:30:91:E4
I have left the PREFIX=24 as commented-out.

I don't know why having PREFIX=24 caused the ifconfig -a to output Mask:255.255.255.0, instead of Mask:255.255.252.0 (as I added the entry NETMASK=255.255.252.0), but at least I have a functioning system.

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TrevorH
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Re: CentOS 6.9 in DELL M4600 - not "networking"

Post by TrevorH » 2017/06/05 06:08:48

PREFIX=24 means 255.255.255.0
CentOS 6 will die in November 2020 - migrate sooner rather than later!
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 is dead, do not use it.
Full time Geek, part time moderator. Use the FAQ Luke

T430s
Posts: 3
Joined: 2017/06/02 15:48:49

Re: CentOS 6.9 in DELL M4600 - not "networking" -Solved

Post by T430s » 2017/06/05 11:04:02

I got it now!
Thank you.

Moderator- please mark it as solved.

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