Re: .PPK keys: VSCODE/Code4i works, PuTTY does not

Hello Sam,

Am 19.02.2026 um 23:04 schrieb Sam_L <lennon_s_j@xxxxxxxxxxx>:

I'm not an expert is public/private keys, but a *long* time ago I created .PPK keys with PuTTY. And I've been able to happily connect to PUB400 with both VSCODE/Code4i and PuTTY without needing a password for months.

I can still connect with Code4i, but as of Feb 16, 2026 PuTTY says "Server refused our key" and defaults to needing a password. (Which it accepts and then connects.)

The one (possibly unrelated for your issue) thing to realize is that PuTTY for some reason did not choose to use the same on-disk format for private and public key files like the usual Unix/Linux, and IBM i Ssh implementation use.

Als always, the interesting point is: What has changed that suddenly PuTTY is forced to ask for a password? In any case, you can't tell from remote, but you need to examine the OpenSSH server's log file on the i. It might be necessary to even stop the server, run in debug mode, try to connect, and then look into the generated log. This isn't exactly IBM i specific. Only the default locations of the files are.

Idea: PTFs might have brought a newer OpenSSH release which disables some deemed-insecure things by default. Checking and installing a current PuTTY release usually fixes these issues.

I tried with PuTTY in Windows CMD and found in the log that it rejected my .PPK key with "invalid format". But this same key works with Code4i. Strange...

That's indeed strange and hints to a local problem on your workstation. Sorry, can't help here. Not a Windows expert. :-)

:wq! PoC