You have to check the following:

1. You are using ssh keys of the user who ran hudson daemon. For example, if user=hudson, then you should log on as hudson and generate ssh keys
2. You have loaded your public key to your server (github, assembla) from correct .ssh/id_rsa.pub file i.e. for the same user who ran hudson daemon
3. You have added RSA fingerprint of your server to your .ssh/known_hosts file

You have to check the following:

1. You are using ssh keys of the user who ran hudson daemon. For example, if user=hudson, then you should log on as hudson and generate ssh keys
2. You have loaded your public key to your server (github, assembla) from correct .ssh/id_rsa.pub file i.e. for the same user who ran hudson daemon
3. You have added RSA fingerprint of your server to your .ssh/known_hosts file