title: "Unable to use key file "...\id_rsa" (OpenSSH SSH-2 private key)" when authenticating with PuTTY
body: <p>I have setup custom SSH keys on target Linux <code>host2</code>.</p>
  
  <p>I'm  able to passwordless ssh from Linux <code>host1</code> to <code>host2</code> using the below command.</p>
  
  <pre><code>ssh -i /app/misc/myssh_keys/my_id_rsa myuser@host2
  </code></pre>
  
  <p>I then copy the <code>/app/misc/myssh_keys/my_id_rsa</code> to my Windows location <code>C:\putty\my_id_rsa</code></p>
  
  <p>I then try to connect from Windows to Linux <code>host2</code>, but it prompts me for the password instead of passwordless login.</p>
  
  <p>Below is my command:</p>
  
  <pre><code>C:\putty\putty.exe -ssh -i C:\putty\my_id_rsa myuser@host2
  </code></pre>
  
  <p>I'm getting the following output with the password prompt:</p>
  
  <pre><code>Unable to use key file "C:\putty\my_id_rsa" (OpenSSH SSH-2 private key)
  Using username "myuser".
  myhost@host2's password:
  </code></pre>
  
  <p>Below is the system details for Linux <code>host2</code></p>
  
  <pre><code>uname -a
  Linux host2 3.10.0-1062.1.2.el7.x86_64 #1 SMP Mon Sep 16 14:19:51 EDT 2019 x86_64 x86_64 x86_64 GNU/Linux
  </code></pre>
  
  <p>Below is the system details for Windows host</p>
  
  <pre><code>C:\Users&gt;systeminfo
  
  Host Name:                 mywinhost
  OS Name:                   Microsoft Windows 7 Professional
  OS Version:                6.1.7601 Service Pack 1 Build 7601
  OS Manufacturer:           Microsoft Corporation
  OS Configuration:          Member Workstation
  OS Build Type:             Multiprocessor Free
  Registered Owner:          hp
  Registered Organization:   Hewlett-Packard Company
  Product ID:                00321-OEM-8552671-07008
  Original Install Date:     01-04-2017, 13:05:14
  System Boot Time:          15-12-2019, 14:00:52
  System Manufacturer:       HP
  System Model:              HP 280 G2 MT (Legacy)
  System Type:               x64-based PC
  Processor(s):              1 Processor(s) Installed.
                             [01]: Intel64 Family 6 Model 94 Stepping 3 GenuineIntel ~3700 Mhz
  BIOS Version:              AMI A0.25, 06-02-2017
  </code></pre>
  
  <p>I read somewhere on Stack Overflow that I may have to convert the <code>C:\putty\my_id_rsa</code> key using PuTTYgen, but I would appreciate the exact commands and all the steps I would need to perform to get the ssh working. </p>
  
  <p>Any other solution would also be appreciated.</p>