[SOLVED] CentOS DHCP Interface

T3RM1NVT0R · 03-18-2015, 11:09 AM

There is something seriously wrong, why eth4 showing the IP address of eth3? Run the following commands and paste the output:

1.

Code:

lspci | grep net

2.

Code:

route -n

3.

Code:

ifconfig -a

4.

Code:

service NetworkManager status

5.

Code:

service network status

6.

Code:

chkconfig --list | egrep '(network)|(NetworkManager)'

7.

Code:

ls -al /etc/sysconfig/network-scripts/ | grep ifcfg

If for security reasons you want to mask the IP just change the first octet. I mean if you are using 192. then you can change it to 10. or 172. Please do not change the subnet mask or anything else as it might be more confusing for me.

JJJCR · 03-18-2015, 10:41 PM

lspci | grep net - no output

but lspci only have this:

Quote:

[vmx@xvmm01 root]# lspci
00:00.0 Host bridge: Intel Corporation 440BX/ZX/DX - 82443BX/ZX/DX Host bridge (AGP disabled) (rev 03)
00:07.0 ISA bridge: Intel Corporation 82371AB/EB/MB PIIX4 ISA (rev 01)
00:07.1 IDE interface: Intel Corporation 82371AB/EB/MB PIIX4 IDE (rev 01)
00:07.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 02)
00:08.0 VGA compatible controller: Microsoft Corporation Hyper-V virtual VGA

ifconfig -a have this: (eth3 and eth4 is on different subnet)

eth3 192.168.1.X subnet
eth4 192.168.2.X subnet

Quote:

[vmx@xvmm01 ~]$ ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever

2: eth3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:17:5c:7d:13:ee brd ff:ff:ff:ff:ff:ff
inet 192.168.1.24/24 brd 192.168.1.255 scope global eth3
valid_lft forever preferred_lft forever

3: eth4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:17:7d:7d:1a:21 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.24/24 brd 192.168.1.255 scope global eth4
inet 192.168.2.120/24 brd 192.168.2.255 scope global eth4
valid_lft forever preferred_lft forever

service NetworkManager status

Quote:

[vmx@xvmm01 ~]# service NetworkManager status
NetworkManager (pid 1243) is running...

service network status

Quote:

[vmx@xvmm01 ~]# service network status
Configured devices:
lo eth0
Currently active devices:
lo eth3 eth4

JJJCR · 03-18-2015, 10:43 PM

ls -al /etc/sysconfig/network-scripts/ | grep ifcfg

Quote:

[vmx@xvmm01 ]# ls -al /etc/sysconfig/network-scripts/ | grep ifcfg
-rw-r--r--. 3 root root 437 Mar 18 16:59 ifcfg-eth0
-rw-r--r--. 1 root root 254 Oct 10 2013 ifcfg-lo

Thanks for your help.

JJJCR · 03-18-2015, 10:45 PM

chkconfig --list output change : to = cannot post

Quote:

chkconfig --list | egrep '(network)|(NetworkManager)'
NetworkManager 0=off 1=off 2=on 3=on 4=on 5=on 6=off
network 0=off 1=off 2=on 3=on 4=on 5=on 6=off

T3RM1NVT0R · 03-18-2015, 11:39 PM

1. vi /etc/sysconfig/network-scripts/ifcfg-eth1 and put the following contents:

Code:

DEVICE=eth4
BOOTPROTO=dhcp
ONBOOT=yes
IPV6INIT=no
USERCTL=yes

2. Turn off NetworkManager using the following command:

Code:

chkconfig NetworkManager off

Also, share the output of the route -n as requested in previous post and:

Code:

cat /etc/sysconfig/network-scripts/ifcfg-eth0

JJJCR · 03-19-2015, 12:06 AM

route -n

Quote:

# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth3
192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth4
192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth4
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth3
0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 eth4

T3RM1NVT0R · 03-19-2015, 12:07 AM

Alright. Looks good. Did you try the steps mentioned in previous post and restarted the network?

JJJCR · 03-19-2015, 12:27 AM

Wow you save my day.. +++T3RM1NVTOR

Thank you very much..

As per your suggestion i turned off NetworkManager and created below files:

-created ifcfg-eth1 with device set to eth4
-created also ifcfg-eth2 with device set to eth3
The default settings of ifcfg-eth0 i never do anything i just leave the default config.

and reboot the VM works like magic...

route -n shows this one, below no more 192.168.2.1 gateway but the subnet still accessible using the 192.168.1.1 gateway..

Quote:

# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth3
192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth4
192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth4
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth3

Maybe I can conclude that NetworkManager could be messing up.

And the ifconfig should be set in sequence like ifcfg-eth0 then ifcfg-eth1 then ifcfg-eth2 and so on..

Yes everything works fine now..Thank you buddy..

T3RM1NVT0R · 03-19-2015, 12:34 AM

You're welcome.

Good to hear that everything works fine now.

Yes, when making configuration change via files it is better to keep NetworkManager off. As I mentioned earlier NetworkManager is a legacy tool. It is there for the people who are new to Linux to give gui / tui access in order to setup the network.

NetworkManager has got drawbacks as well for example you cannot configure alias IP on the interface with NetworkManager running. It simply mess it up.

JJJCR · 03-19-2015, 12:38 AM

Quote:

Originally Posted by T3RM1NVT0R

You're welcome.

Good to hear that everything works fine now.

Yes, when making configuration change via files it is better to keep NetworkManager off. As I mentioned earlier NetworkManager is a legacy tool. It is there for the people who are new to Linux to give gui / tui access in order to setup the network.

NetworkManager has got drawbacks as well for example you cannot configure alias IP on the interface with NetworkManager running. It simply mess it up.

Yes, thank you. Command line works great..but of course need to know what to type..hehehe...

T3RM1NVT0R · 03-19-2015, 12:39 AM

You're welcome. Yup that is true

JJJCR · 03-19-2015, 12:43 AM

There was an issue also the fstab was not mounting a windows share.

But I guess it was the network issue also; when the OS try to mount but the network was not yet connected so it fails.

But now everything works as expected..

T3RM1NVT0R Thank you..