How to convert SSH keypairs generated using PuTTYgen Windows into key-pairs used by ssh-agent and Keychain Linux

Question

I ve generated key pairs using PuTTYgen and been logging in using Pageant  so that I have to enter my pass-phrase only once when my system boots    How do I achieve this in Linux  I ve heard of keychain but I hear that it uses a different key pair format - I don t want to change my Windows keys and it would be nice if I could seamlessly connect in the same manner in both Windows and Linux

User · Answer

PPK   OpenSSH RSA with PuttyGen  amp  Docker   Private key   docker run --rm -v   pwd   app zinuzoid puttygen private ppk -O private-openssh -o my-openssh-key   Public key   docker run --rm -v   pwd   app zinuzoid puttygen private ppk -L -o my-openssh-key pub   See also https   hub docker com r zinuzoid puttygen

User · Answer

puttygen supports exporting your private key to an OpenSSH compatible format   You can then use OpenSSH tools to recreate the public key    Open PuttyGen Click Load Load your private key Go to Conversions- gt Export OpenSSH and export your private key Copy your private key to    ssh id dsa  or id rsa   Create the RFC 4716 version of the public key using ssh-keygen  ssh-keygen -e -f    ssh id dsa  gt     ssh id dsa com pub  Convert the RFC 4716 version of the public key to the OpenSSH format   ssh-keygen -i -f    ssh id dsa com pub  gt     ssh id dsa pub    See this and this for more information

User · Answer

Alternatively if you want to grab the private and public keys from a PuTTY formated key file you can use puttygen on  nix systems  For most apt-based systems puttygen is part of the putty-tools package   Outputting a private key from a PuTTY formated keyfile     puttygen keyfile pem -O private-openssh -o avdev pvk  For the public key     puttygen keyfile pem -L

User · Answer

I recently had this problem as I was moving from Putty for Linux to Remmina for Linux  So I have a lot of PPK files for Putty in my  putty directory as I ve been using it s for 8 years  For this I used a simple for command for bash shell to do all files   cd    putty for X in   ppk  do puttygen  X -L  gt     ssh   echo  X   sed  s         sed  s  ppk  g   pub  puttygen  X -O private-openssh -o    ssh   echo  X   sed  s         sed  s  ppk  g   pvk  done    Very quick and to the point  got the job done for all files that putty had  If it finds a key with a password it will stop and ask for the password for that key first and then continue

User · Answer

sudo apt-get install putty   This will automatically install the puttygen tool   Now to convert the PPK file to be used with SSH command execute the following in terminal  puttygen mykey ppk -O private-openssh -o my-openssh-key   Then  you can connect via SSH with   ssh -v user example com -i my-openssh-key   http   www graphicmist in use-your-putty-ppk-file-to-ssh-remote-server-in-ubuntu  comment-28603

User · Answer

It s probably easier to create your keys under linux and use PuTTYgen to convert the keys to PuTTY format     PuTTY Faq  A 2 2

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If all you have is a public key from a user in PuTTY-style format  you can convert it to standard openssh format like so   ssh-keygen -i -f keyfile pub  gt  newkeyfile pub   References   Source  http   www treslervania com node 408 Mirror  https   web archive org web 20120414040727 http   www treslervania com node 408    Copy of article     I keep forgetting this so I m gonna write it here  Non-geeks  just   keep walking       The most common way to make a key on Windows is using Putty Puttygen    Puttygen provides a neat utility to convert a linux private key to   Putty format  However  what isn t addressed is that when you save the   public key using puttygen it won t work on a linux server  Windows   puts some data in different areas and adds line breaks       The Solution  When you get to the public key screen in creating your   key pair in puttygen  copy the public key and paste it into a text   file with the extension  pub  You will save you sysadmin hours of   frustration reading posts like this       HOWEVER  sysadmins  you invariably get the wonky key file that throws   no error message in the auth log except  no key found  trying   password  even though everyone else s keys are working fine  and   you ve sent this key back to the user 15 times   ssh-keygen -i -f keyfile pub  gt  newkeyfile pub       Should convert an existing puttygen public key to OpenSSH format

User · Answer

I think what TCSgrad was trying to ask  a few years ago  was how to make Linux behave like his Windows machine does   That is  there is an agent  pageant  which holds a decrypted copy of a private key so that the passphrase only needs to be put in once   Then  the ssh client  putty  can log in to machines where his public key is listed as  authorized  without a password prompt   The analog for this is that Linux  acting as an ssh client  has an agent holding a decrypted private key so that when TCSgrad types  ssh host  the ssh command will get his private key and go without being prompted for a password   host would  of course  have to be holding the public key in    ssh authorized keys   The Linux analog to this scenario is accomplished using ssh-agent  the pageant analog  and ssh-add  the analog to adding a private key to pageant    The method that worked for me was to use    ssh-agent  SHELL That  SHELL was the magic trick I needed to make the agent run and stay running   I found that somewhere on the  net and it ended a few hours of beating my head against the wall   Now we have the analog of pageant running  an agent with no keys loaded   Typing   ssh-add  by itself will add  by default  the private keys listed in the default identity files in    ssh    A web article with a lot more details can be found here

User · Answer

Newer versions of PuTTYgen  mine is 0 64  are able to show the OpenSSH public key to be pasted in the linux system in the  ssh authorized keys file  as shown in the following image

[git] How to convert SSH keypairs generated using PuTTYgen (Windows) into key-pairs used by ssh-agent and Keychain (Linux)

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