$ git remote -v
origin  ssh://git@github.com/kdopen/json-c (fetch)
origin  ssh://git@github.com/kdopen/json-c (push)
upstream    git@github.com:json-c/json-c.git (fetch)
upstream    ssh://git@github.com/json-c/json-c.git (push)

$ git pull upstream master
$ git push origin master