I use ssh key authentication to rsync data from my weather station to it’s website. Mysteriously it started failing a few days ago. After a bit of hair pulling and unhelpful ssh -vvv output, I found the cause. The permissions of the authorized_keys file on the server were incorrect.
-rw-rw-r– 1 stan4dnet pg478973 391 2008-05-07 12:14 authorized_keys
This file is readable by more than just you. Newer versions of ssh see this, recongize it as a security hole, and prevent you from doing something stupid. Lesson Learned: Make sure that the files in .ssh are writable only by you, on both machines, and non-executable by anyone.
Some people recommend a simple “chmod 644 *” in your .ssh directories. I don’t. I recommend:
chmod 400 *