How to resolve User key not recognized by server issue of EC2 server by Raj Gupta

If you use PuTTY to connect to your instance

1.  Verify that your private key (.pem) file has been converted to the format recognized by PuTTY (.ppk).In PuTTYgen, load your private key file and select Save Private Key rather than Generate.

2.  Verify that you are connecting with the appropriate user name for your AMI

• For Amazon Linux 2 or the Amazon Linux AMI, the user name is ec2-user.
• For a CentOS AMI, the user name is centos.
• For a Debian AMI, the user name is admin or root.
• For a Fedora AMI, the user name is ec2-user or fedora.
• For a RHEL AMI, the user name is ec2-user or root.
• For a SUSE AMI, the user name is ec2-user or root.
• For an Ubuntu AMI, the user name is ubuntu.
• Otherwise, if ec2-user and root don't work, check with the AMI provider.

3. Verify that you have an inbound security group rule to allow inbound traffic to the appropriate port.

If you use SSH to connect to your instance

• Use ssh -vvv to get triple verbose debugging information while connecting:

ssh -vvv -i [your key name].pem ec2-user@[public DNS address of your instance].compute-1.amazonaws.com

[root@ip-172-31-91-224 ~]# ssh -vvv -i raj.pem ec2-user@ec2-54-91-231-121.compute-1.amazonaws.com

then we will get output like below which help us in debugging

open/ANT/myusername/.ssh/known_hosts). debug2: bits set: 504/1024 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: boguspem.pem ((nil)) debug1: Authentications that can continue: publickey debug3: start over, passed a different list publickey debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Trying private key: boguspem.pem debug1: read PEM private key done: type RSA debug3: sign_and_send_pubkey: RSA 9c:4c:bc:0c:d0:5c:c7:92:6c:8e:9b:16:e4:43:d8:b2 debug2: we sent a publickey packet, wait for reply debug1: Authentications that can continue: publickey debug2: we did not send a packet, disable method debug1: No more authentication methods to try. Permission denied (publickey). 

If you use SSH (MindTerm) to connect to your instance

• If Java is not enabled, the server does not recognize the user key. To enable Java, go to

Internet Explorer

1. Click Tools and then Internet Options
2. Select the Security tab, and select the Custom Level button
3. Scroll down to Scripting of Java applets
4. Make sure the Enable radio button is checked
5. Click OK to save your preference