ifup eth0: unknown host

Question

unfortunately, i am in Ubuntu Recovery Mode.
I need Internet connection but, i fail to bring it up.

$ ifconfig
enp0s2  Link encap:Ethernet HWaddr xxxx
        inet addr:
        inet6 addr:
       ...
lo      Link encap:local
       ...

$ sudo ifup enp0s2
Ignoring unknown interface enp0s2=enp0s2

$ sudo ifconfig up enp0s2
enp0s2: Unknown host

The router has connection to the Internet and the laptop is proper connected via cable.

So, why nobody loves me?
And, how do i bring Ethernet up?

BTW: why is it 'enp0s2' and not 'eth0' as usual?

Solution

Remount root read-write:

mount -o remount,rw /

This is so you can edit files under /etc/.

Edit /etc/network/interfaces

Add:

auto enp0s2
iface enp0s2 inet dhcp

Run: ifup enp0s2

It is 'enp0s2' and not 'eth0' because of kernel modifications that were added to support Predictable Network Interface Names

Comments

[Panther]

did you remount your root partition rw ? see wiki.ubuntu.com/RecoveryMode

[b-boy]

Nice. 'ifup' works now. But, still i can't 'ping google.com'. It says 'unknown host'.

[Acceptable Name]

Edit /etc/resolv.conf add nameserver 8.8.4.4

[b-boy]

Nope. ping still aint working. Although, i didnt restart anything.

[Acceptable Name]

Does ping -n 8.8.4.4 work?

[b-boy]

$ ping -n 8.8.4.4 connect: Network is unreachable

[b-boy]

Sorry, my bad. A typo in /etc/network/interfaces. Works now. (Although, one question from the initial post still unanswered...)

[Acceptable Name]

Nobody loves you because you don't understand what love is. If you understood what love is you would realize how much you are loved.

[pivanchy]

@MettaCrawler, will this solution work, if I want to enable eth0? And what is the reason of remounting root?