ubutu14 networking

$ ip a show

Note the default Ethernet and wifi interfaces:
ip-a-show

It looks like our Ethernet port is eth0. Our WiFi radio is wlan0. Want to make this briefer?

    $ ip a show | awk  '/^[0-9]: /{print $2}'

The output of this command will look something like this:

lo:
eth0:
wlan0:

Your gateway IP address is found with:

    route -n

It provides access to destination 0.0.0.0 (everything). In the below image it is 192.168.0.1, which is perfectly nominal.

route-n

#Remove network manager
apt-get purge network-manager

Let’s do a bit of easy configuration in our /etc/networking/interfaces file. The format of this file is not difficult to put together from the man page, but really, you should search for examples first.
interfaces
Plug in your Ethernet port.

Basically, we’re just adding DHCP entries for our interfaces. Above you’ll see a route to another network that appears when I get a DHCP lease on my Ethernet port. Next, add this:

 

    auto lo
    iface lo inet loopback
    auto eth0
    iface eth0 inet dhcp
    auto wlan0
    iface wlan0 inet dhcp
    
Next, enable and start the networking service:

    sudo update-rc.d networking enable

 

    sudo /etc/init.d/networking start

Let’s make sure this works, by resetting the port with these commands:

    sudo ifdown eth0
    sudo ip a flush eth0
    
        sudo ifup eth0

This downs the interface, flushes the address assignment to it, and then brings it up. Test it out by pinging your gateway IP: ping 192.168.0.1. If you don’t get a response, your interface is not connected or your made a typo.

Let’s “do some WiFi” next! We want to make an /etc/wpa_supplicant.conf file. Consider mine:

    network={
    ssid="CenturyLink7851"
    scan_ssid=1
    key_mgmt=WPA-PSK
    psk="4f-------------ac"
    }

Now we can reset the WiFi interface and put this to work:

    sudo ifdown wlan0

 

    sudo ip a flush wlan0
    
        sudo ifup wlan0

 

    sudo wpa_supplicant -Dnl80211 -c /root/wpa_supplicant.conf -iwlan0 -B

 

    sudo dhclient wlan0

That should do it. Use a ping to find out, and do it explicitly from wlan0, so it gets it’s address first:

 

    $ ip a show wlan0 | grep "inet"
    
    Presumably dhclient updated your /etc/resolv.conf, so you can also do a:

    ping -I 192.168.0.45 www.yahoo.com

Well guess what – you’re now running without NetworkManager!