Unable to ssh into EC2 instance

Question

I first tried to ssh into my EC2 instance and I got this:

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 
Permissions 0644 for '/Users/SidRama/Downloads/ec2.pem.txt' are too open.
It is required that your private key files are NOT accessible by others.
This private key will be ignored.
Load key "~/Downloads/ec2.pem.txt": bad permissions
Permission denied (publicly).

So I ran:

sudo chmod 400 ~/Downloads/ec2.pem.txt

Then I executed this

ssh -i  ~/Downloads/ec2.pem.txt ec2-user@ec2-52-35-59-123.us-west-2.compute.amazonaws.com -v

But I get Permission denied (publicly) as below:

OpenSSH_6.9p1, LibreSSL 2.1.8
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 20: Applying options for *
debug1: /etc/ssh/ssh_config line 53: Applying options for *
debug1: Connecting to ec2-52-35-59-123.us-west-2.compute.amazonaws.com [52.35.59.111] port 22.
debug1: Connection established.
debug1: key_load_public: No such file or directory
debug1: identity file ~/Downloads/ec2.pem.txt type -1
debug1: key_load_public: No such file or directory
debug1: identity file ~/Downloads/ec2.pem.txt-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.9
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6.1
debug1: match: OpenSSH_6.6.1 pat OpenSSH_6.6.1* compat 0x04000000
debug1: Authenticating to ec2-52-35-59-123.us-west-2.compute.amazonaws.com:22 as 'ec2-user'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client chacha20-poly1305@openssh.com  none
debug1: kex: client->server chacha20-poly1305@openssh.com  none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:ZJbD9iVRP/8EbzmhyBvrC+Vg2W15k+A5cB6dea3+BAA
The authenticity of host 'ec2-52-35-59-123.us-west-2.compute.amazonaws.com (52.35.59.111)' can't be established.
ECDSA key fingerprint is SHA256:ZJbD9iVRP/8EbzmhyBvrC+Vg2W15k+A5cB6dea3+BAA.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'ec2-52-35-59-123.us-west-2.compute.amazonaws.com,52.35.59.111' (ECDSA) to the list of known hosts.
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: ~/Downloads/ec2.pem.txt
debug1: Authentications that can continue: publickey
debug1: Trying private key: ~/Downloads/ec2.pem.txt
debug1: Authentications that can continue: publickey
debug1: No more authentication methods to try.
Permission denied (publickey).

I have been trying for some time now. Any help would be deeply appreciated. Thanks in advance.

Answer 1

A few things I would do:

1. In Amazon, create an elastic IP and assign it to your instance
2. Use an absolute path and try a different syntax, I usually just do :

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sudo ssh -i /somepath/key.pem ec2-user@51.62.132.180

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3. Reset the known hosts from where you are trying to connect:

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sudo ssh-keygen -R 51.62.132.180    
sudo ssh-keyscan -H 51.62.132.180 >> ~/.ssh/known_hosts

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4. Double check the IP of the instance and the path to the key

5. Remove the .txt extension from the key file