O openssh usa um formato de chave diferente do putty. Você precisaria usar puttygen
para converter / exportar sua chave putty em um formato que o openssh possa usar.
- Open PuttyGen
- Click Load
- Load your private key
- Go to Conversions->Export OpenSSH and export your private key
- Copy your private key to ~/.ssh/id_dsa (or id_rsa).
Create the RFC 4716 version of the public key using ssh-keygen
ssh-keygen -e -f ~/.ssh/id_dsa > ~/.ssh/id_dsa_com.pub
Convert the RFC 4716 version of the public key to the OpenSSH format:
ssh-keygen -i -f ~/.ssh/id_dsa_com.pub > ~/.ssh/id_dsa.pub
Fix the permissions of the private keyfile:
chmod 600 ~/.ssh/id_dsa
Extraído de: link