SSH to my AWS server just broke for both Putty and Filezilla. I'm making some effort for this post to be a comprehensive troubleshooting list, so if you share links to other stack overflow pages, I'll edit them into the question.
Disconnected : No supported authentication methods available (server sent :publickey)
The error is familiar from when I set up the connection almost a year ago. If you're setting up AWS SSH for the first time, these address the most common problems:
However, the only thing I could think that would impact a previously working system is:
What other possibilities are there?
Solution to this one (per the accepted post below) is that for AWS EC2 all 3 of these need to have proper permissions (777 not ok for any of these). Here's one example that works:
/home/ec2-user/ - 700
/home/ec2-user/.ssh/ - 600
/home/ec2-user/.ssh/authorized_keys - 600
/var/log/secure will tell you which one is throwing an error, consult this video tutorial to get access if you're completely locked out: http://d2930476l2fsmh.cloudfront.net/LostKeypairRecoveryOfLinuxInstance.mp4
For me this error appeared immediatey after I changed the user's home directory by
sudo usermod -d var/www/html username
It can also happen because of lack of proper permission to authorized_key file in ~/.ssh. Make sure the permission of this file is 0600 and permission of ~/.ssh is 700.