// update the remote tracking branches
$ git fetch
// fetch and checkout the change
// (checkout command copied from change screen)
$ git fetch https://gerrithost/myProject refs/changes/74/67374/2 && git checkout FETCH_HEAD
// do the rebase
$ git rebase origin/master
// resolve conflicts if needed and stage the conflict resolution
...
$ git add <path-of-file-with-conflicts-resolved>
// continue the rebase
$ git rebase --continue
// push the commit with the conflict resolution as new patch set
$ git push origin HEAD:refs/for/mastergit reset $(git commit-tree HEAD^{tree} -m 'Новое начало истории')
Служба OpenSSH тоже не нужна для коммуникации с GitHub, у неё совсем другое назначение.