The name of your SSH key means that it won't be offered by default, you need to specify it when connecting:
Code:
ssh -i ${KEY_PATH} root@kindle
You can also add it to .ssh/config to avoid the need to do this every time:
Code:
Host kindle
User root
Hostname 192.168.15.244
IdentityFile $KEY_PATH
KexAlgorithms +diffie-hellman-group1-sha1
StrictHostKeyChecking no