Strange IP address issue, Linux

binarysoul

Hello Linuxers,

I'm playing with CentOS and when I run 'ifconfig' I get 10.0.0.5 as IP. But when I look at /etc/sysconfig/network-scripts/ifcfg-eth0, it shows IP as 10.1.1.1. This is a VM in Virtualbox.

I had previously changed IP to 10.0.0.5, but it shouldn't be there. I've used ifconfig to change IP back, rebooted, but it doesn't change.

Any idea?

UnixGuy

is it CentOS 6.x ? The network might be controlled by "NetworkManager".

in the file /etc/sysconfig/network/ifcfg-eth0
NMCONTROLLED="yes" ?

change it to "no"

then do this:
"server NetworkManager stop"
"chkconfig NetworkManager off"

or what I do is "yum remove NetworkManager"

binarysoul

Thanks for the tip. It worked, but after I rebooted, the problem is back! It's Centos 6.32.

'ifconfig' shows 10.0.0.5 as IP

/etc/sysconfig/network-scripts/ifcfg-eth0, shows IP as 10.1.1.1

I get PING replies from 10.0.0.5.

But when I ping 10.1.1.1, I get replies From ip 10.0.0.5 that 10.1.1.1 is unreachable!

darkerosxx

Post your file.

UnixGuy

Sorry about the reboot. Instead of reboot, you needed to just reset the network service (service network restart).

this is strange. Can you copy paste the contents of this file: "/etc/sysconfig/network-scripts/ifcfg-eth0" and the contents of this file "/etc/sysconfig/network"

also, the outputs of "ifconfig" and "netstat -rn"


try this command as well: "ifdown eth0", then "ifup eth0", it might post a message on why you're not acquiring the IP in the files

ccnxjr

Can we see the full output of :

ifconfig -a

ip addr

dmesg | grep eth

Just a tiny peek

binarysoul

Thanks everyone! I've attached the output of everything you asked for and put them in a screenshot. Please use this link:

View image: output

ccnxjr

One more thing, can you give us the output of :

cat /etc/udev/rules.d/70-persistent-net.rules

I find it odd that there is a vlan assosciated with eth0 from the output of dmesg.


here's mine for reference:

[root@cacti ~]# dmesg|grep eth0
e1000 0000:00:03.0: eth0: (PCI:33MHz:32-bit) 08:00:27:d6:33:0c
e1000 0000:00:03.0: eth0: Intel(R) PRO/1000 Network Connection
e1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
[root@cacti ~]#

Can you also run

ls /proc/net/vlan/

If there is a vlan of some sort configured let's start digging there.

If a vlan is configured then vlan sub-interfaces *should* show up under the output of

ifconfig -a

But that *looks* ok, so I guess we'll have to put on our sleuthing hats for this after all !

binarysoul

Here is the output. Actually, there is no VLAN, but it's a VM on a VirtualBox.

View image: rules

UnixGuy

It looks alright, just change BOOTPROTO from "static" to "none". Static is no longer a valid option

BOOTPROTO="none"

Then do a "service network restart"

Since it's a virtualbox, it's worth checking your VirtualBox network config, sometimes they result in funny errors

ally_uk

might be worth also checking your virtual box network settings are set to bridged

binarysoul

Bingo!

I changed BOOTPROTO and played around with Virtualbox network settings. It's fixed!

Thanks everyone. I could have rebuilt the box, but I often want to learn from such strange problems than quickly 'throwing the white towel at the ring'.

W Stewart

Interesting. Didn't know static wasn't valid anymore. I haven't used a redhat based distro in awhile. Most supporting ubuntu these days.