Amazon-web-services – scp (secure copy) to ec2 instance without password

Basically, you need a private-key file to login into your EC2 via SSH. Follow these steps to create one:

• Go https://console.aws.amazon.com/ec2/home & sign in to your existing Amazon account.
• Click on "Key Pairs" on LHS or https://console.aws.amazon.com/ec2/home?region=us-east-1#s=KeyPairs.
  • You should see the list of KEYs generated by you (or during EC2 creation process).
  • Click on "Create Key Pair" if you don't see any or you lost your private-key.
  • Enter a unique name and hit enter.
  • A download panel will appear for you to save the private-key, save it.
  • Keep it somewhere with the file permission "0600"
• Click on "Instances" on LHS or https://console.aws.amazon.com/ec2/home?region=us-east-1#s=Instances
  • You should see the list of ec2-instances, if you don't see any, then please create one.
  • Click on the EC2 machine and note down the Public DNS address.
• Open your Terminal (in Linux) and type the following command
  • ssh -i /path/to/private-key root@<ec2-public-dns-address> - the root username has been avoided in the latest releases, based on your distribution select ec2-user or ubuntu as your username.
  • hit Enter
  • That's it.

This answer is useful in the case you no longer have SSH access to the existing server (i.e. you lost your private key).

If you still have SSH access, please use one of the answers below.

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-key-pairs.html#replacing-lost-key-pair

Here is what I did, thanks to Eric Hammond's blog post:

1. Stop the running EC2 instance
2. Detach its /dev/xvda1 volume (let's call it volume A) - see here
3. Start new t1.micro EC2 instance, using my new key pair. Make sure you create it in the same subnet, otherwise you will have to terminate the instance and create it again. - see here
4. Attach volume A to the new micro instance, as /dev/xvdf (or /dev/sdf)
5. SSH to the new micro instance and mount volume A to /mnt/tmp

$ sudo mkdir /mnt/tmp; sudo mount /dev/xvdf1 /mnt/tmp

6. Copy ~/.ssh/authorized_keys to /mnt/tmp/home/ubuntu/.ssh/authorized_keys
7. Logout
8. Terminate micro instance
9. Detach volume A from it
10. Attach volume A back to the main instance as /dev/xvda
11. Start the main instance
12. Login as before, using your new .pem file

That's it.