Cannot acquire DHCP address

Question

I am unable to acquire a wired DHCP ip address.

I have Ubuntu 13.10 installed on a thin mini-itx ECS Q77H2-TI motherboard. I'm connecting to my cable modem which does provide ip addresses to other (windows, mac osx) machines I've connected to it.

When I run ifconfig I see:

eth1      Link encap:Ethernet  HWaddr 74:27:ea:c2:62:58          
          inet6 addr: fe80::7627:eaff:fec2:6258/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:267 errors:0 dropped:0 overruns:0 frame:0
          TX packets:516 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:50017 (50.0 KB)  TX bytes:111906 (111.9 KB)
          Interrupt:20 Memory:f7c00000-f7c20000 

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:65536  Metric:1
          RX packets:1624 errors:0 dropped:0 overruns:0 frame:0          
          TX packets:1624 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0    
          RX bytes:132240 (132.2 KB)  TX bytes:132240 (132.2 KB)

cat /etc/network/interfaces gives:

auto lo
iface lo inet loopback

When I try tcpdump -i eth0 -n, I see nothing, but tcpdump -i eth1 -n, I see plenty of activity when wired.

I would love some pointers on how to get this machine connected to the internet.

Cheers,

Owen.

Solution 1

Your pc view only eth1 interface. Ifconfig don't see eth0. You can try with nm-tool command to see nic card, state ... Simple output will be like this

$ nm-tool
NetworkManager Tool
State: connected
- Device: eth0  [Auto eth1] ----------------------------------------------------
 Type:              Wired
 Driver:            xxxxx
 State:             connected
 Default:           yes
 HW Address:        74:27:ea:c2:62:58
 Capabilities:
 Carrier Detect:  yes
 Speed:           100 Mb/s
 Wired Properties
 Carrier:         on
 IPv4 Settings:
 Address:         xxx.xxx.xxx.xxx
 Prefix:          24 (255.255.255.0)
 Gateway:         xxx.xxx.xxx.xxx
 DNS:             xxx.xxx.xxx.xxx
 DNS:             xxx.xxx.xxx.xxx

Also you can try to renew ip settings from dhcp server first

ifconfig eth1 down

next

ifconfig eth1 up

or

dhclient eth1

You will probably get ip from dhcp ...

If is your cable in eth0 interface try to up interface

ifconfig eth0 up

Solution 2

To answer my own question,

1. I added a dhcp entry to /etc/network/interfaces

   auto eth1
   iface eth1 inet dhcp
   

2. I then restarted my cable modem. The modem appears to only provide one DHCP ip address per power cycle.

Fixed.

Comments

[2707974]

Your problem is fixed and this is enough. Happy hacking :)

[neouyghur]

You saved my day.