Let’s say you’ve got written a bash script that scans all of your Linux servers in your knowledge heart for uptime. This file could comprise the next contents:
ssh $1 "uptime"
When you run the script, it could be thwarted by a problem the place it’s interrupted by a server that has but to have its SSH key fingerprint added to the known_hosts file. When this occurs, your script is rendered unusable.
SEE: How to view SSH keys in Linux, macOS, and Windows (TechRepublic)
SSH key fingerprint
What is an SSH key fingerprint? Simple: The key fingerprint is verified once you attempt to log in to a distant pc utilizing SSH. When you log into an SSH server for the primary time, you will notice one thing comparable to what’s proven beneath.
If you don’t settle for the fingerprint, the connection will probably be instantly terminated. So what occurs once you work with a bash script that may’t settle for enter to permit distant SSH fingerprinting to be added?
Luckily, the SSH builders considered this and added a command that permits you to simply add SSH fingerprints to the known_hosts file.
SEE: How to create and duplicate SSH keys with 2 easy instructions (TechRepublic)
Adding fingerprint
I’ll display including fingerprint from a distant server to an area pc. Let’s say the distant server is 192.168.1.162. To add that fingerprint, the command can be:
ssh-keyscan -H 192.168.1.162 >> ~/.ssh/known_hosts
The command will run and add the distant SSH fingerprint to the native pc with out your enter, as proven beneath.
So an addition to the bash script may appear like:
ssh-keyscan $1 >> ~/.ssh/known_hosts
The above addition would take the argument from the command (say, for instance, ./script 192.168.1.118) and add the fingerprint to ~/.ssh/known_hosts earlier than transferring on to the subsequent line, thus avoiding the lacking SSH fingerprint downside. Of course the above would solely work correctly you probably have an ssh key authentication setup. Otherwise, you need to enter the password of the distant machine.
SEE: How to mount distant directories with SSH (TechRepublic)
The easy issues
Sometimes, it is the easy issues that journey up our bash scripts. If the important thing fingerprint problem has been inflicting you complications along with your scripts, now you can keep away from the issue.
