I can't pull/fetch from origin, but can push my story branch

[Arup Rakshit <aruprakshit@rocketmail.com>]

Hi,

I forked a repo and then working on features using feature branch. Once done, I am pushing my branch and creating PR. This all was working till night. Suddenly this morning, I am not able to fetch/pull, but can push my feature. The below is what I am getting:

[arup@critique (master)]$ git fetch origin
[arup@critique (master)]$
[arup@critique (master)]$ git pull origin master
ssh: Could not resolve hostname ssh.github.com: Name or service not known
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
[arup@critique (master)]$
[arup@critique (master)]$ git remote -v
origin  git@github.com:aruprakshit/critique.git (fetch)
origin  git@github.com:aruprakshit/critique.git (push)
upstream        git@github.com:DFTi/critique.git (fetch)
upstream        git@github.com:DFTi/critique.git (push)
[arup@critique (master)]$

Any idea what configuration got change over night ? I have no idea how to fix it? Please help me.
 Regards,
Arup Rakshit