How to connect via Terminal (SSH) Ubuntu to EC2 amazon??

Question

SSH

This is what we have
[email protected]:~/Downloads$ ssh -i "app.pem" [email protected]
The authenticity of host 'ec2-52-10-201-193.us-west-2.compute.amazonaws.com (52.10.201.193)' can't be established.
ECDSA key fingerprint is 11:86:0a:97:72:c5:41:ce:4d:3c:d1:05:6f:5e:0d:4b.
Are you sure you want to continue connecting (yes/no)? yes
Please type 'yes' or 'no': yes
Warning: Permanently added 'ec2-52-10-201-193.us-west-2.compute.amazonaws.com,52.10.201.193' (ECDSA) to the list of known hosts.
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@ WARNING: UNPROTECTED PRIVATE KEY FILE!
Permissions 0664 for 'app.pem' are too open.
It is required that your private key files are NOT accessible by others.
This private key will be ignored.
bad permissions: ignore key: app.pem
Permission denied (publickey).
[email protected]:~/Downloads$ ssh -i "app.ppk" [email protected]
Enter passphrase for key ' app.ppk':
Permission denied (publickey).

Answer 1

chmod 0600 app.pem

Answer 2

When I log in, I just enter public ip, not DNS IP, as you enter. And there are no connection problems.