AWS - Disconnected : No supported authentication m

Question

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:

• Wrong username: Disconnected : No supported authentication methods available (server sent :publickey)
• Incorrect .ppk file: Unable to connect to amazon server using putty

However, the only thing I could think that would impact a previously working system is:

• Wrong IP: Restarting an AWS instance (or creating an image) is not guaranteed to keep the same IP address. This would obviously have to be updated in putty.

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

Answer 1

I had the same problem, I used Public DNS instead of Public IP. It resolved now.

Answer 2

I had the same problem, by accident mistake. I'll share it here, in case someone may have made the same mistake.

Basic steps, as others described.

1. Download putty and puttygen, or the putty package and install it.
2. Get the .pem file from your AWS EC2 instance.
3. Use puttygen to convert the .pem file so that you'll have a private key --- mistake happened here. I chose "Conversions" tab from PuttyGen, and load my .pem file. After loading pem file, here DO NOT hit "Generate", instead directly "Save private key". That's the key you need. If you click Generate, you'll have a totally different pair of keys.
4. In putty, use [e-mail], and load the private key at SSH/Auth

Good luck!

Answer 3

A similar issue happened with me today. I also had searched alot about this.No one help. I just made two changes and its get working properly as well.

1. I had visited Amazon documentation where describe either Verify that there is a rule that allows traffic from your computer to port 22 (SSH) and if not present, create it and edit "Security Group" and add "SSH" to my IP. This will help.
2. In my case, In putty profile, I have to again authorize with .ppk file. I don't know why it ask again, without any changes made.

Hope it will help you.

Answer 4

You will also receive "Disconnected : No supported authentication methods available (server sent :publickey)" when you have a correct Linux user but you haven't created the file .ssh/authorized_keys and saved the public key as indicated in Managing User Accounts on Your Linux Instance

Answer 5

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.

Answer 6

There is another cause that would impact a previously working system. I re-created my instances (using AWS OpsWorks) to use Amazon Linux instead of Ubuntu, and received this error after doing so. Switching to use "ec2-user" as the username instead of "ubuntu" resolved the issue for me.