Generate pub file from pem file

공개키를 생성하는 방법이다.

# ssh-keygen -y

Enter file in which the key is (/root/.ssh/id_rsa): a.pem

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

Permissions 0644 for 'a.pem' are too open.

It is recommended that your private key files are NOT accessible by others.

This private key will be ignored.

bad permissions: ignore key: a.pem

Enter passphrase:

위 상황은 pem 파일의 권한이 너무 열려있는 케이스이다. chmod 0400 으로 권한 변경한다.

# ssh-keygen -y

Enter file in which the key is (/root/.ssh/id_rsa): a.pem

ssh-rsa ....

ssh-rsa 부터가 생성된 공개키다.