Setup private and public keys

ssh_rsa_key.sh

# Forgotten passphrase for private ssh key
# you need to remove your SSH public/private keys, recreate them, 
# and then add your newly created public key to the servers 
# and online services you use.

# Remove your SSH public/private keys:
rm ~/.ssh/id_rsa*

# Recreate the keypair, choosing a new passphrase:
ssh-keygen -t rsa -f ~/.ssh/id_rsa

# Add the newly created private key to your OS X Keychain to store the passphrase and manage unlocking it automatically:
ssh-add -K ~/.ssh/id_rsa

# Copy the public key to the OS X clipboard for adding to web services like GitHub, etc.
cat ~/.ssh/id_rsa.pub | pbcopy

# Add your newly created public key to the ~/.ssh/authorized_keys file of the remote server. 
# Be sure to ensure the correct permissions of both the remote ~/.ssh folder (700) and ~/.ssh/authorized_keys (600). 
# You may want to investigate using ssh-copy-id to ease this process.

# Source: https://superuser.com/questions/760907/forgot-password-to-id-rsa