Converting a PuTTY key for an OpenSSH client

A .ppk file and an OpenSSH private-key file are different encodings used by different clients. Converting the file does not create a new authorized account or make a server trust the key automatically.

The Linux sequence

sudo apt-get install putty-tools

puttygen ppkkey.ppk -O private-openssh -o pemkey.pem

cp pemkey.pem ~/.ssh

chmod 400 pemkey.pem

ssh -i pemkey.pem user@ec2-instancedotcom

The copied destination and the file whose permissions are changed must be the same intended key. Paths in the original short sequence assume the corresponding working directory.

The reverse conversion was:

puttygen pemKey.pem -o ppkKey.ppk -O private

The macOS sequence

brew install putty

puttygen privatekey.ppk -O private-openssh -o privatekey.pem

chmod go-rw privatekey.pem

ssh -i privatekey.pem ec2-user@my.server.com

-o selects the output file and -O selects the format. These historical commands include private-key outputs; no key files were imported, converted, or used to connect for this revision.

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