How to squash commits in git after they have been pushed?

Question

This gives a good explanation of squashing multiple commits:

http://git-scm.com/book/en/Git-Branching-Rebasing 

but it does not work for commits that have already been pushed. How do I squash the most recent few commits both in my local and remote repos?

EDIT: When I do git rebase -i origin/master~4 master, keep the first one as pick, set the other three as squash, and then exit (via c-x c-c in emacs), I get:

$ git rebase -i origin/master~4 master

# Not currently on any branch.

nothing to commit (working directory clean)

Could not apply 2f40e2c... Revert "issue 4427: bpf device permission change option added"

$ git rebase -i origin/master~4 master

Interactive rebase already started

where 2f40 is the pick commit. And now none of the 4 commits appear in git log. I expected my editor to be restarted so that I could enter a commit message. What am I doing wrong?

Answer 1

$ git rebase -i HEAD~4

After running this command, you will be taken into an interactive page. Now replace pick with squash at the top for all the commits that you want to squash.

Don't forget to save and close the editor using Esc > :wq

All you need to do now is push these changes to the remote:

$ git push origin branch-name --force