Windows/Share Putty key with Cygwin

Simple guide for sharing the same keypair in putty and cygwin (openssh).

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  Starting fresh

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  Start by running puttygen.exe (not bundled with putty, must be downloaded separately)

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  Press "generate" to start.

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  Type in the machine name.

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  Export the (private) key in a format OpenSSH understands.

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  Save the file in C:\cygwin\home\USER\.ssh\id_rsa

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  Copy the public key (the select text in the image)

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  Paste it in a text editor.

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  Optionally change the line-ending to UNIX format.

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  Save the file in C:\cygwin\home\USER\.ssh\id_rsa.pub

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  Validate fingerprint.

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  Export private key in PPK format.