Background

I’ve been primarily a Linux/Mac OS X-based developer for the last year or so. However, I recently moved back to Microsoft and so figured that I should refamiliarize myself with Windows development. I have, of course, become completely dependent upon the standard tools such as ssh. Being the security-minded fellow I am, I will continue to fanatically refuse to use ssh with password-based authentication instead of public-private key pairs. While ports of all these tools, of course, exist for Windows, it is not always so straightforward to use them in what is a completely natural way. Here I will describe in detail my experiences setting up Mercurial over ssh with passwordless authentication and encryption. I’m going to use TortoiseHg since it includes PuTTY, which is a fairly nice Windows implementation of ssh. While these steps have been detailed many times before, I will repeat them here for anyone who’s interested.

Downloads

• Download and install tortoisehg-1.1.7-hg-1.7.2-x64.msi from here
• Download and install plink.exe from here
• Download and install putty.exe from here
• Download and install puttygen.exe from here

Prerequisites

• A Linux server with sshd and password-based authentication disabled
• A Windows client machine
• Another Windows/Linux/Mac OS X machine that already has public keys exchanged with the Linux server and thus has a trust relationship established with it

Steps

• Run puttygen.exe
• Select SSH-2 RSA and enter 2048 in Number of bits in a generated key
• Click on Generate
• Move mouse as per the instructions in order to generate randomness
• Set a passphrase in Key passphrase and Confirm passphrase
• Save the public and private keys using Save public key and Save private key
• Copy the public key into the clipboard from Public key for pasting into OpenSSH authorized_keys file
• Using the already trusted machine, upload the public key to the server and append its contents to the authorized_keys in the .ssh directory
• Create a new Mercurial.ini file in your home directory with the following content:

[ui]
ssh = TortoisePlink.exe -i "C:/path/to/ppk-file.ppk"

• Start Pageant.exe (which has equivalent functionality to OpenSSH’s ssh-agent)
• Add the private key to Pageant
• You should now be able to clone/push/pull etc. to/from the server

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