How to set up password-less SSH login for a Dropbear client

This blog post was published 7 years ago and may or may not have aged well. While reading please keep in mind that it may no longer be accurate or even relevant.

Dropbear is a replacement for OpenSSH for environments with low memory and processor resources. With OpenSSH, you can use the well-known ssh-keyen command to create a private/public keypair for the client. In Dropbear, it is a bit different. Here are the commands on the client:

mkdir ~/.ssh
chmod 700 ~/.ssh/
dropbearkey -t rsa -f ~/.ssh/id_dropbear

Both private and public keys will be in ~/.ssh/id_dropbear, however, in a binary format.

To output the public key to stdout in the usual SSH-compatible format, use:

dropbearkey -y -f ~/.ssh/id_dropbear
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