I can ssh into EC2 from the cloud shell, but not from my Mac terminal. Any troubleshooting tips?

Question

Hello!
I'm by no means an AWS expert, so I'm throwing this out there with the hopes someone knows the answer.

I have been trying to SSH into my EC2 instance from the Mac terminal, but keep getting "connection refused". When I do this via Cloud Shell however, everything works fine. In both environments, I follow the same steps:
1. created a private/public key via ssh-keygen
2. add the public key to my security credentials
3. run the ssh command: `ssh ec2-.compute-1.amazonaws.com`

I have a feeling something might be wrong on my Mac. Do I need to clear any settings? Looks like the ssh-agent has no stored keys.

Answer

Is the error message just "Connection refused" or is there any more to it? Does this come up right away, or does it wait for a while?

You'll likely need the username as part of your command, this varies according to the OS (on Amazon Linux and RHEL it's `ec2-user`, CentOS it's `centos`, Ubuntu it's `ubuntu`) and also specify your private key in the command (I know you say you've saved it to your profile, but no harm in explicitly stating it just for troubleshooting). So something like `ssh -i /path/to/mykeyfile.pem ec2-user@ec2-.compute-1.amazonaws.com`

if ithis still fails, try verbose mode to get more detailed error messages `ssh -vvv -i ....`

This AWS doc may help too https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AccessingInstancesLinux.html#AccessingInstancesLinuxSSHClient

Answer

Its probably the Security Group attached to EC2 Instance.

1. Check the security group settings for your EC2 instance, and see if the inbound rules allow SSH traffic from your IP address ( or for testing alone set it to 0.0.0.0/0) . You can check this in the EC2 console under the "Security Groups" section.

2. Set the correct permissions  to your private key : 
```
 chmod 400 /path/to/private/key.
```

If you're using a different username on the EC2 instance than your local username, you'll need to specify the correct username when you SSH. For example, if your EC2 instance uses the username "ec2-user", you would run the following command:

```
ssh -i /path/to/private/key ec2-user@ec2-.compute-1.amazonaws.com.
```
to get more details of your issue you can try -v flag for verbose.

```
ssh -v -i /path/to/private/key ec2-.compute-1.amazonaws.com.
```

I can ssh into EC2 from the cloud shell, but not from my Mac terminal. Any troubleshooting tips?

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