From Monday June 19th, 2-factor authentication is required if you log in with ssh to login.astro.uio.no from outside the UiO-network. See here for more information.
If you use scp, sftp or sshfs and need to do this without 2FA, you can do that to scp.astro.uio.no. More information here.
For a few days login2.astro.uio.no will be available without 2FA, but will then require require 2FA (most likely by the end of next week). login2.astro.uio.no will serve as an alternative way in if login.astro.uio.no has problems.