Technology Tales

Automated entry of SSH passwords

17^th February 2022

A useful feature for shell scripting is automatic password entry when logging into other servers. This often involves plain text files, which are not secure. Fortunately, I found an alternative. The first step is to use the keygen tool included with SSH. The command is shown below. The -t switch defines the key type, RSA in this example. You can add a passphrase, but I chose not to for convenience. You should evaluate your security requirements before implementing this approach.

ssh-keygen -t rsa

The next step is to use the ssh-copy-id command to generate the keys for a set of login credentials. For this, it is better to use a user account with restricted access to keep as much server security as you can. Otherwise, the process is as simple as executing a command like the following and entering the password at the prompt for doing so.

ssh-copy-id [user ID]@[server address]

Getting this set up has been useful for running a file upload script to keep a web server synchronised, and it is better to have the credentials encrypted rather than kept in a plain text file.