Ubuntu network manager and disappering nm-applet icon

I had this strange issue with my Ubuntu install when the nm-applet icon a.k.a. network icon disappeared from the task bar. After much effort i found out a work around that was to stop network-manager application and then launch nm-applet and then restart the network-manager application.

But the solution to this is a very simple one, and as it turned out was not a bug.
If you are faced with such a situation do make sure to checkout your /etc/network/interfaces file to see that the interface is not listed. If the interface is listed in that file remove it else the network-manager wont take over that interface by default.

sudo service network-manager stop
nm-applet &
sudo service network-manager stop

Sample lines in /etc/network/interfaces

auto eth0
iface eth0 inet dhcp
auto eth1
iface eth1 inet static
address 192.168.244.2
netmask 255.255.255.0
gateway 192.168.244.244
 

Comment out the interface you want network manager to take over, in this case eth0

#auto eth0
#iface eth0 inet dhcp

auto eth1
iface eth1 inet static
address 192.168.244.2
netmask 255.255.255.0
gateway 192.168.244.244
 

Then you may simply restart your pc or you can simply restart the networking using

sudo /etc/init.d/networking restart 

Dell 1545 wireless and Ubuntu

As it turns out wireless network does not work on Dell 1545 in Ubuntu. Here is a simple solution

Ubuntu:
------
Go to System->Administration->Hardware Drivers
Choose the Broadcom STA wireless driver
Activate

Sometimes the driver does not show up in the Hardware Drivers choices. In
this case, try reinstalling the driver from the GUI or shell like this:

From the GUI:
Package Manager (System>Administration>Synaptic Package Manager). Click the
Reload button in the upper left corner of Synaptic to refresh your index then
search for and reinstall the package named bcmwl-kernel-source.

Code:

sudo apt-get update
sudo apt-get --reinstall install bcmwl-kernel-source 

in case the package was not already installed try
Code:

sudo apt-get install bcmwl-kernel-source

In either GUI or text case, after reinstalling, reboot your machine.

Or you may wish to download and manually install the driver from this link http://www.broadcom.com/support/802.11/linux_sta.php


Ndiswrapper method

If you don not have luck with the above method or you have a different device then you can try the Ndiswrapper technique. A detailed walk-through is given here https://help.ubuntu.com/community/WifiDocs/Driver/Ndiswrapper. For the curious, basically Ndiswrapper allows you to install and use windows drivers on Ubuntu. Good ain't it :D

Network bridging in VirtualBox

For those of you working on the ARP project you need to send and receive packets form your Ubuntu VM to the actual physical network. In order to do this you would need to setup network adapter to Bridged networking. In this mode you can sniff traffic on the actual physical network from within your VM and also inject packets into it.

Note: You should turn of Vbox DHCP server before you proceed. In order to do so follow my older post http://zaidmunir.blogspot.com/2010/07/how-to-enabledisable-virtualboxs-dhcp.html

Follow these steps for a hassle free setup.
1. Shut down VM.
2. Open its settings in VBox and goto settings->network
3. Over here click on all the adapter tabs and make sure that enable adapter is unchecked. You should only check this for the adapter you wish to use. In our case adapter 1.
4. In the 'Attached to' field select 'Bridged adapter' and in the 'name' field select the name of the adapter you want to make the bridge with.
5. Now run your VM and find out the name for your interface using the command ifconfig. In this example it is assumed to be eth1.
6. In case the DHCP server on your local LAN physical LAN is working follow step 7 or jump to step 8.
7. Now open and edit the /etc/network/interfaces file. It should look something like this

Preview:

auto lo
iface lo inet loopback

auto eth1
iface eth1 inet dynamic

And now you can try pinging the host machine and machines on the physical network and all should be well :)

8. See the network settings for your host machine. Now we wish to assign the guest machine an IP which is on the same network as that of the host machine. In my case the host machine has the following configuration

Preview:

IP 172.16.1.10
subnet 255.255.0.0
default gateway 172.16.1.1
DNS 172.16.1.1

So my /etc/network/interfaces file looks something like this

Preview:

auto lo
iface lo inet loopback

auto eth1
iface eth1 inet static
address 172.16.1.103
netmask    255.255.0.0
gateway 172.16.1.1

9. You will now be able to ping the host machine and others machines on the physical network. But you will still not be able to browse through the web. For this you need to make an entry for the DNS server in /etc/resolv.conf

Make the following entries in the file

Preview:

search com
nameserver 172.16.1.1

Note: the entries in your case should correspond to your particular network settings.

Networking lab

For this lab you will need this manual. Its hard copy has been placed at the photocopier. You are to submit a hard copy at the end of the lab.

All help material has been posted on the blog here.

How to enable/disable VirtualBox's DHCP server.

Goto File -> Preferences -> Network



Now select the VirtualBox Host-only Ethernet adapter and edit it as shown below, then in the DHCP server tab un-check Enable server.


Now press OK twice and you should theoretically be done, but due to a bug in VBox the DHCP is not truly disabled till the time you restart the host machine (The machine on which VBox is running).

Configuring network interfaces in Ubuntu

As a first step you should know which interfaces are configured in your machine. You can start by listing all the interfaces using the command: ifconfig

eth1 Link encap:Ethernet HWaddr 08:00:27:31:34:d7
inet addr:10.0.2.15 Bcast:10.0.2.255 Mask:255.255.255.0
inet6 addr: fe80::a00:27ff:fe31:34d7/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1100 errors:0 dropped:0 overruns:0 frame:0
TX packets:1089 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:970170 (970.1 KB) TX bytes:181886 (181.8 KB)

eth2 Link encap:Ethernet HWaddr 08:00:27:96:82:41
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)

eth2:avahi Link encap:Ethernet HWaddr 08:00:27:96:82:41
inet addr:169.254.6.94 Bcast:169.254.255.255 Mask:255.255.0.0
UP BROADCAST MULTICAST MTU:1500 Metric:1

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:240 (240.0 B) TX bytes:240 (240.0 B)

In the output observe the first column it contains the interface name. You need to know which interface you wish to configure. I would be configuring eth2 in the rest that follows, you can replace eth2 by an interface of your choice.

In Ubuntu the main file in which all the network configuration is /etc/network/interfaces.

Before you start editing system files its a good practice to take back up, in case you screw something up, you can restore the file using the backed up file. You can back up the file by using the following command:

sudo cp interfaces interfaces.bak

First, what if you want to make an interface acquire a dynamic configuration using DHCP. in that case open the /etc/network/interfaces using your favorite editor. Note: In order to make changes to this file you need to be an administrator. To do this you need to use the sudo prefix:

sudo gedit /etc/network/interfaces

Look for an entry for the interface on which you wish to use DHCP. If there is one remove it and then add the following:

auto eth2
iface eth2 inet dhcp

Now you need to restart the network. Use the following command:

sudo /etc/init.d/networking restart


Part 2: What if you wish to assign a static configuration to the interface.

Once again open the file /etc/network/interfaces and search for the interface of your choice. Remove all the entries for it below the line auto eth2 (be careful not to remove the configuration for other interfaces). In my case I wish to have the following configuration

Desired new sample settings:
=> Host IP address 192.168.1.100
=> Netmask: 255.255.255.0
=> Network ID: 192.168.1.0
=> Broadcast IP: 192.168.1.255
=> Gateway/Router IP: 192.168.1.254
=> DNS Server: 192.168.1.254

Add the following lines to the file

auto eth2
iface eth2 inet static
address 192.168.1.100
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.254

Once more, now you need to restart networking. For this use the same command as above: sudo /etc/init.d/networking restart

If you want a more advanced tutorial you can follow http://www.cyberciti.biz/tips/howto-ubuntu-linux-convert-dhcp-network-configuration-to-static-ip-configuration.html

Configuring network in virtual box

Please download this manual, it will be helpful in revising your previous concepts.
You additionally need to download and print this manual, you need to submit a filled hard copy at the end of the lab.

Here you can additionally find the link to the online tutorial for virtual box, in this section virtual networking is explained http://www.virtualbox.org/manual/ch06.html
And here is another useful link for changing the IP address in Ubuntu, be advised before you make any changes to these files be sure to take backup of this file.