SSH Private Key in PuTTY Not Working
I have read through every StackExchange Q/A I could find regarding SSH failing with key pairs from PuTTY. I generated an RSA key pair using ssh-keygen on macOS, used ssh-copy-id to copy the public key to the authorized_keys file on my server, and after disabling password authentication I was able to login to the server with the key pair successfully.
I then went over to my Windows PC, opened up PuTTYGen, imported the id_rsa (private key) file, and saved the private key to the ppk format. Yet, when I added this to my PuTTY>Connection>SSH>Auth>Priv.Key and tried logging into my server, I get server refused our key from the console window.
I have tried changing the number of bits from 2048 to 4096 in the PuTTYGen window (since the fingerprint says ssh-rsa 4096), I checked the permissions on the authorized_keys file (600) & its directory (700), used KiTTY and Solar PuTTY as alternatives, and changed the log level to DEBUG3 in the server's sshd_config. After the last, I noticed this:
debug1: trying public key file /root/.ssh/authorized_keys
debug1: fd 4 clearing O_NONBLOCK
debug2: key not found
debug1: restore_uid: 0/0
debug3: mm_answer_keyallowed: key 0x559259bd7e00 is not allowed
Failed publickey for root from 10.0.0.125 port 57253 ssh2: RSA SHA256:...
Honestly, I'm just at a loss for what to try next. I feel like I've tried everything, but I also don't know if I just don't understand the debug logs well enough. Any help is appreciated, thanks.
I had the same issue with the Putty using SSH private key converted to Putty format but server refusing to use it. My solution was:
- Download latest putty and puttygen: e.g. 0.76 from www.chiark.greenend.org.uk
- Regenerate Putty private key using updated puttygen
- Repeat login using latest putty configured to use the regenerated private key
For the private key conversion/export I used the default puttygen settings. The new putty private key ended up with the following header:
PuTTY-User-Key-File-3: ssh-rsa
Encryption: none
Comment: imported-openssh-key
Public-Lines: 6
Hope this helps