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No associated key pair, add key pair to EC2 with no key pair

inac

2/21/23, 3:14 AM

How do you add an existing key to a live EC2 instance that has no key pair?

I have tried using Session Manager to vi /.ssh/authorized_keys and add in the public key of the pair, but I get this error:

"~/.ssh/authorized_keys"
"~/.ssh/authorized_keys" E212: Can't open file for writing

Is this something that has to be done using the console?

No associated key pair
This instance is not associated with a key pair. Without a key pair, you can't connect to the instance through SSH.
You can connect using EC2 Instance Connect with just a valid username. You can connect using Session Manager if you have been granted the necessary permissions.

732

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private-key

public-key

amazon-ec2

key

Dmitriy Kupch

2/21/23, 3:54 AM

Does it have any ssh key installed? If you need to add additional SSH public key to destination .ssh/authorized_keys, I would just run ```ssh-copy-id -i /path/to/publicsshkey.pub $server ip``` There is also a way to add it through the AWS console: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-key-pairs.html

inac

2/21/23, 3:59 AM

It doesn't seem to let me associate the key pair using the AWS console with EC2 instance. I have followed the directions for adding the authorized_keys using ssh using Session Manager (since it has no key pair) - but that does not let me shell in, and the console still indicates no key pair

Dmitriy Kupch

2/21/23, 4:03 AM

Here is what I mean: https://docs.aws.amazon.com/cli/latest/reference/ec2/import-key-pair.html#examples

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Server

MLu

2/21/23, 7:47 AM

Since you’ve got Systems Manager configured you’re half-way there. The only thing standing between you and success is the fact that Systems Manager Session opens the session as ssm-user and you’ll need to do sudo -u ec2-user -i first and once you're logged in as ec2-user do the subsequent steps.

Then you may have to create the ~ec2-user/.ssh directory if it doesn’t exist and chmod it to 700.

And finally you can add the public key to ~ec2-user/.ssh/authorized_keys and chmod that file to 600.

That should do the trick :)

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inac

2/21/23, 10:03 PM

That works temporarily - after the session or on restart/reboot, it seems it is wiped out maybe by some sort of AWS global daemon.

MLu

2/21/23, 10:07 PM

If the key is in `~ec2-user/.ssh/authorized_keys` it will stay there. But it sounds like you put it to `~ssm-user/.ssh/…` - that home directory is wiped as soon as you log out from the SSM session.

inac

2/21/23, 10:09 PM

ah, your directions did not indicate ~ec2-user/ being base directory...

MLu

2/21/23, 10:12 PM

Yeah I said that you have to do `sudo -u ec2-user -i` first and once you're logged in as `ec2-user` do the subsequent steps. Sorry, should have been more explicit. I have updated the answer.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: No associated key pair, add key pair to EC2 with no key pair

TH: ไม่มีคู่คีย์ที่เกี่ยวข้อง เพิ่มคู่คีย์ใน EC2 โดยไม่มีคู่คีย์

RO: Fără pereche de chei asociată, adăugați pereche de chei la EC2 fără pereche de chei

RU: Нет связанной пары ключей, добавьте пару ключей в EC2 без пары ключей

VI: Không có cặp khóa được liên kết, hãy thêm cặp khóa vào EC2 mà không có cặp khóa nào

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