unable to SSH into aws ec2 instance with gitbash: permission denied

Question

I encountered the permission denied error while trying to ssh into my aws ec2 instance - centos with a valid private key (.pem) file using the windows gitbash.Debug logs are as given below.

OpenSSH_8.1p1, OpenSSL 1.1.1d  10 Sep 2019
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Connecting to ec2-#####.ap-south-1.compute.amazonaws.com [####] port 22.
debug1: Connection established.
debug1: identity file mbrace.pem type -1
debug1: identity file mbrace.pem-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.1
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.4
debug1: match: OpenSSH_7.4 pat OpenSSH_7.0*,OpenSSH_7.1*,OpenSSH_7.2*,OpenSSH_7.3*,OpenSSH_7.4*,OpenSSH_7.5*,OpenSSH_7.6*,OpenSSH_7.7* compat 0x04000002
debug1: Authenticating to ec2-13-126-107-143.ap-south-1.compute.amazonaws.com:22 as 'centos'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:5Qu3MuE9zz27Ywx1d+dQyZwaC8KN/khaRLIRSUVLZ6s
debug1: Host 'ec2-13-126-107-143.ap-south-1.compute.amazonaws.com' is known and matches the ECDSA host key.
debug1: Found key in /c/Users/####/.ssh/known_hosts:1
debug1: rekey out after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey in after 134217728 blocks
debug1: Will attempt key: mbrace.pem  explicit
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic
debug1: Next authentication method: publickey
debug1: Trying private key: mbrace.pem
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic
debug1: No more authentication methods to try.
centos@ec2-######.ap-south-1.compute.amazonaws.com: Permission denied (publickey,gssapi-keyex,gssapi-with-mic).

Tried all methods given in the forum including changing permissions of.ssh folder and.pem file, but to no use. Do guide us as where we are going wrong.

Answer 1

Will attempt key: mbrace.pem explicit

That means you have a /c/Users/####/.ssh/config file which does explicitly reference in an IndentityFile filed the mbrace.pem file.
You need to make sure, following " EC2: Connect to your Linux instance using SSH ", that (to emulate ssh -i /path/my-key-pair.pem my-instance-user-name@my-instance-public-dns-name ):

• the remote user (field User in the SSH config file) is the correct one ( my-instance-user-name )
• the key (private mbrace.pem in IdentityFile ) is referenced through its full path ( ~/.ssh/mbrace.pem works, even on Windows)
• the matching public key is visible in the .ssh/authorized_keys file on the instance .
• the inbound SSH traffic from your IP address to your instance is enabled