3

Since I upgraded my HP Proliant Server from Ubuntu 10.04 to 12.04, I am unable to:

  • ping google.com
  • ping 8.8.8.8
  • browse the internet with Firefox
  • git fetch origin
  • cap deploy from a remote machine

I can however see my Rails application running on this server when I access it via its ip address within our corporate network.

I see the Networking icon in the GUI but "Wired Network" is greyed out.

Here is some other relevant info, based on the numerous similar but non-resolving threads I've browsed here at AU:

dean@dgwjasonfried:~$ ifconfig

eth0      Link encap:Ethernet  HWaddr 1c:c1:de:fa:cd:9f  
          inet addr:10.24.5.50  Bcast:10.24.5.255  Mask:255.255.255.0
          inet6 addr: fe80::1ec1:deff:fefa:cd9f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:40735 errors:0 dropped:0 overruns:0 frame:0
          TX packets:77215 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2806140 (2.8 MB)  TX bytes:113945803 (113.9 MB)
          Interrupt:19 

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:22 errors:0 dropped:0 overruns:0 frame:0
          TX packets:22 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:1872 (1.8 KB)  TX bytes:1872 (1.8 KB)

dean@dgwjasonfried:~$ lspci -nn | grep Ethernet

1e:00.0 Ethernet controller [0200]: Broadcom Corporation NetXtreme BCM5723 Gigabit Ethernet PCIe [14e4:165b] (rev 10)

/etc/network/interfaces:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet dhcp

/etc/resolv.conf:

domain dgw.ame.molex.com
search dgw.ame.molex.com
nameserver 10.24.2.171
nameserver 10.45.2.171

**Updated 3/19/13, after trying to follow some of the advice give in responses below and elsewhere:

dean@dgwjasonfried:~$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 127.0.0.1
search dgw.ame.molex.com
domain dgw.ame.molex.com
search dgw.ame.molex.com
nameserver 10.24.2.171
nameserver 10.45.2.171

**end of update

Kernel IP routing table

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.24.5.1       0.0.0.0         UG    0      0        0 eth0
10.24.5.0       0.0.0.0         255.255.255.0   U     1      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 eth0

**Updated to show NetworkManager.conf and evidence that the resolv.conf symlink is working for me

dean@dgwjasonfried:~$ cat /etc/NetworkManager/NetworkManager.conf
[main]
plugins=ifupdown,keyfile
dns=dnsmasq

[ifupdown]
managed=true

dean@dgwjasonfried:~$ ls -l /etc/resolv.conf
lrwxrwxrwx 1 root root 29 Mar 18 09:33 /etc/resolv.conf -> ../run/resolvconf/resolv.conf

**Updated to show latest resolv.conf after I deleted original in /etc/resolvconf/resolv.conf.d and cleared out the copy of original that was sitting in tail, then rebooted:

dean@dgwjasonfried:/etc/resolvconf/resolv.conf.d$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 127.0.0.1
search dgw.ame.molex.com

Note that the nameserver entries listed in an earlier resolv.conf version above are now gone. Also note that whereas I was briefly able to get ping google.com to resolve the ip address for google.com (but still not receive any packets back) I'm now back to my original situation where I get 'unknown host google.com'.

**end of update

I'd be grateful for any help you could supply or suggestions you might have.

Thanks!

Dean Richardson

Dean Richardson
  • 81

3 Answers3

4

I think it would be beneficial to step back, teach a man how to fish instead of just telling you what's wrong.

There are many components involved in making a good network connection

  • It can be the hardware: ethernet card, cable contacts, network interface on your directly connected switch, etc.
  • It can be the low level software: the kernel driver for your network card
  • It can be your routing table
  • It can be DNS

And these are all dependent on each other from the bottom up, e.g. if you can't route packets correctly, you can't reach your DNS service.

There's only one (sane) way to pinpoint the issue that I know of: one by one, by elimination.

One sentence stands out in your description:

I can however see my Rails application running on this server when I access it via its ip address within our corporate network.

It is great that you tried this. This piece of information is golden because it eliminates many possible causes. It means that your hardware and your (kernel) drivers and the connections inside the corporate network all look fine. This is also confirmed by the fact that the ifconfig output shows packets being sent and received and no (zero) errors, collisions, or retransmissions. At this point I'm sure your issue is in your configuration only.

I notice that your internal DNS server is at (non-public) IP: 10.24.2.171, this is not on your immediate subnet 10.24.5.0, you can tell this by this ifconfig output line:

inet addr:10.24.5.50  Bcast:10.24.5.255  Mask:255.255.255.0

Note that your mask leaves only the last of the 4 octets as 0, meaning you're broadcasting only over the 10.24.5.x subnet. You may not have a full route to your internal DNS server.

The experiment I would do now would be to try and verify the routes to your essential components:

  1. Your gateway 10.24.5.1
  2. Your name server 10.24.2.171

It is essential to do these by IP since we don't yet know if your DNS server is ok and if you can talk to it.

# first traceroute the gateway:
traceroute 10.24.5.1

If this fails with an error like no route to host or destination is unreachable, it is almost certain that your issue is in the routing table. If it is successful you've just made a huge step forward because routing is a big subject by itself.

# if successful traceroute the DNS server
traceroute 10.24.2.171

If this fails, your issue may be that the netmask is too restrictive. Try to change it to 255.255.0.0. You can set this in /etc/network/interfaces by adding:

netmask 255.255.0.0

under eth0.

Once you fixed this, you would need to restart your network:

sudo /etc/init.d/networking restart

HTH

arielf
  • 2,883
1

One of the problems is that resolvconf did not get configured properly. Ref: https://bugs.launchpad.net/ubuntu/+source/resolvconf/+bug/1000244. To fix this, run

    sudo dpkg-reconfigure resolvconf

This, however, can't be the reason that you cannot ping other machines by IP address.

jdthood
  • 12,625
0
eth0      Link encap:Ethernet  HWaddr 1c:c1:de:fa:cd:9f  
      inet addr:10.24.5.50  Bcast:10.24.5.255  Mask:255.255.255.0

10.* interfaces often have netmask 255.0.0.0. Check that the netmask is correct for your LAN.

jdthood
  • 12,625