DHCP IP not being brought up
 

Hi,

I have made a CentOS AMI Image for Amazon EC2
Now the network is starting but it doesnt even try to determine the IP :
Bringing up interface eth0: [ OK ]

BUT if I hit the ifconfig :
eth0 Link encap:Ethernet HWaddr 12:31:39:0A:99:F8
inet6 addr: fe80::1031:39ff:fe0a:99f8/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:90 (90.0 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:4 errors:0 dropped:0 overruns:0 frame:0
TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:316 (316.0 b) TX bytes:316 (316.0 b)

What could be possibly wrong ?
The network script is not even trying to determine the IP.
Please help.

How are you connecting to the network (wired or wireless)? And how are you getting your IP (DHCP or static)?

My guess is probably wired+DHCP, and if so, you probably just need to run "dhcpcd eth0" (or another DHCP client) in order to get assigned an IP address. If not, then tell us a bit more about your setup and we might have more chance of working out what's going wrong :) the "Bringing up the interface eth0" message doesn't say anything about actually connecting to the internet.

Hope this helps,

Hi,

Its a VM on Amazons EC2.
So yes its wired and DHCP.

Isnt "dhcpcd eth0" supposed to run on startup ??

--
Nothing wrong with it; an UP and RUNNING interface without an IP is normal.
You should check the configuration to see if the interface is set with BOOTPROTO=dhcp. Otherwise, you can set it manually.

To make sure if there's a DHCP server running on the network segment, invoke the client to get an address :

Hi,

Is "dhclient eth0" to be called after NETWORK startup or before ?

Hi,

you can call dhclient at any time, if it succeeded, then your interface should be set with a valid address, a default gateway and DNS IP. You should see something like this :

From this point you should check the configuration file, /etc/sysconfig/network-scripts/ifcfg-eth0, and set it with BOOTPROTO=dhcp, and you're good to go.