SSH to new Lightsail instance

Question

I just started using AWS, and I don't think I have upgraded my Lightsail instance properly I started out with a free tier small instance running Ubuntu. It is working just fine, but I had some memory issues and decided to upgrade to the next size up on the free tier. I followed the instructions in this article: https://lightsail.aws.amazon.com/ls/docs/en_us/articles/how-to-create-larger-instance-from-snapshot-using-console. The process seemed to work properly, but I can't connect to the instance directly with the browser-based ssh client. If I use the browser connection, I get a CLIENT_UNAUTHORIZED [769] error. I looked at this article: https://aws.amazon.com/premiumsupport/knowledge-center/lightsail-resolve-ssh-console-errors/, but it didn't seem to apply as both instances are running Ubuntu 22.04.1 LTS and /etc/ssh/sshd_config had CASignatureAlgorithms set to ssh_rsa (CASignatureAlgorithms +ssh-rsa). If I use PuTTY, I can connect. What can I/should I do to get the ssh link to work?

I tried rebooting, and I tried deleting and recreating the instance. Neither allowed me to connect with the browser-based ssh client in my lightsail dashboard. I normally connect with PuTTY, but the original instance was working fine a couple of days ago with the browser-based client. I've never been able to use the browser-based client to connect to this new instance.

Thanks for any help and suggestions--

Al

I tried rebooting, and I tried deleting and recreating the instance.  Neither allowed me to connect with the browser-based ssh client in my lightsail dashboard.  I normally connect with PuTTY, but the original instance was working fine a couple of days ago with the browser-based client.  I've never been able to use the browser-based client to connect to this new instance.

Thanks for any help and suggestions--

Al

Answer

Hello, your problem can be resolve by adding the following properties and values to `/etc/ssh/sshd_config`
```
TrustedUserCAKeys /etc/ssh/lightsail_instance_ca.pub
PubkeyAcceptedKeyTypes +ssh-rsa-cert-v01@openssh.com,ssh-rsa
PubkeyAcceptedAlgorithms +ssh-rsa-cert-v01@openssh.com,ssh-rsa
CASignatureAlgorithms +ssh-rsa
```
After you update the config file, you can run the following command to make sure you have a good config
```
sshd -T
```
After that, you can run the following command to restart sshd

```
sudo systemctl restart sshd
```

browser based ssh would be recover for your instance.

SSH to new Lightsail instance

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