Ubuntu issues with IP

Question

I'm having a really odd issue where ifconfig and my /etc/network/interfaces disagree. I have /etc/network/interfaces configured so eth0 has a static IP of 192.168.2.5; however, ifconfig says eth0's IP is 192.168.2.198 (in my DHCP range). As far of the rest of my network is concerned, the machine is located at 192.168.2.198 . I've tried restarting networking (/etc/init.d/networking restart) twice now, and that didn't resolve the issue.

/etc/network/interfaces

auto lo
iface lo inet loopback

iface ppp0 inet ppp
provider ppp0

auto ppp0

iface eth0 inet static
address 192.168.2.5
netmask 255.255.255.0
gateway 192.168.2.1

ifconfig

eth0  Link encap:Ethernet  HWaddr 00:19:b9:6d:a2:b1
      inet addr:192.168.2.198  Bcast:192.168.2.255  Mask:255.255.255.0
      inet6 addr: fe80::219:b9ff:fe6d:a2b1/64 Scope:Link
      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
      RX packets:301767 errors:0 dropped:0 overruns:0 frame:0
      TX packets:76931 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000
      RX bytes:153435880 (146.3 MB)  TX bytes:9934052 (9.4 MB)
      Interrupt:22

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:23150 errors:0 dropped:0 overruns:0 frame:0
      TX packets:23150 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:0
      RX bytes:9998881 (9.5 MB)  TX bytes:9998881 (9.5 MB)

wlan0 Link encap:Ethernet  HWaddr 00:19:7e:60:e7:b5
      UP BROADCAST MULTICAST  MTU:1500  Metric:1
      RX packets:0 errors:0 dropped:0 overruns:0 frame:0
      TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000
      RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
      Interrupt:16 Memory:ecffc000-ed000000

Can you post your interfaces file? – Dennis Williamson Sep 19 '09 at 02:14 — Dennis Williamson, Sep 19 '09 at 02:14

score 2 · Accepted Answer · answered Sep 19 '09 at 06:25

You don't have eth0 flagged as "auto" in /etc/network/interfaces. This means restarting networking is going to ignore that interface and it will just keep whatever config it already had (apparently a DHCP assigned address).

Try this:

Run "ifconfig eth0 0 down"
Edit /etc/network/interfaces and add auto eth0 above the definition of the eth0 interface.
Run "ifup eth0". It should come up with the address you assigned in /etc/network/interfaces.

You may also want to check your process table for an instance of dhclient. If it's there, kill it.

Greeblesnort · Answer 2 · 2009-09-19T04:24:28.667

0

can you post the output of:

cat /etc/network/interfaces

and

ifconfig

edit: oops, I missed one:

nm-tool

I'm betting that NetworkManager is why your interface is pulling DHCP. Check Preferences > Network Connections.

edited Sep 19 '09 at 04:24

answered Sep 19 '09 at 02:18

Greeblesnort

1,739
8
10

score -1 · Answer 3 · answered Sep 19 '09 at 04:31

Below is my /etc/network/interfaces file for a static IP running Ubuntu:

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
address 10.10.100.17
netmask 255.255.255.0
network 10.10.100.0
broadcast 10.10.100.255
gateway 10.10.100.1

Can you confirm that you are intentionally using the point to point protocol? Also, are you wanting PPP or PPPoE? If you are needing to use PPP, would the following work?

auto lo
iface lo inet loopback

iface ppp0 inet ppp
      provider myisp

auto eth0
iface eth0 inet static
address 192.168.2.5
netmask 255.255.255.0
broadcast 192.168.2.255
gateway 192.168.2.1

In the above, you'll need to replace myisp with your specific isp info. Also, if you are using PPP, could you post the output of:

cat /etc/ppp/options   # or any other interesting files in this directory
cat ~/.ppprc

I'm pretty sure the ppp interface was there since I installed the OS. — Alex S, Sep 20 '09 at 03:20

Ubuntu issues with IP

3 Answers3