Copying ssh keys easily

I use VMs/Vagrant a lot in my day work for all sysadmin/devops automation. One of the problems that I always face with the systems is to authorize my server for the 1st time with my master host. If I am using 10 VMs I need to authorize them 10 times? I wrote a small script to automate this process:

1. Create a "list" file and add all IPs and hostnames for the VMs in it.
2. Create a "password" file to write your SSH password in it, you may choose to write the password in the bash, however I feel this gives me the flexibility to add the bash to my source code if need by putting password file in a.gitignore
3. Next create a shell script that will read the IP addresses and the hostnames from the "list" file and password/s from the password file(I generally keep the same password for all VMs for simplicity)
4. Remember 2 commands are useful here ssh-copy-ip and ssh-keyscan. Here's how you use them:

 

ssh-keyscan -H <IP> >> ~/.ssh/known_hosts sshpass -f <password> ssh-copy-id -i ~/.ssh/id_rsa.pub <USER>@<IP>

The ssh-keyscan command command is for gathering the public ssh host key of a VM host specified. After collecting the publich ssh-key it adds it to your localhost. You can verify this by checking the contents of "~/.ssh/known_hosts"

The ssh-copy-id command copies the public key of your default identity (otherwise use -i identity_file for other identities) to the remote host. You can verify this by checking the content on ~/.ssh/authorized_keys in the VM host.

The final script looks like this with a loop:

#!/bin/bash user="vagrant" for ip in `cat ./list`; do ssh-keyscan -H $ip >> ~/.ssh/known_hosts sshpass -f password.txt ssh-copy-id -i ~/.ssh/id_rsa.pub $user@$ip done

That's how my "list" file looks like:

consul-server1 consul-server2 bootstrap-server1 client1 client2 client3 client4 client5 192.168.3.111 192.168.3.112 192.168.3.121 192.168.3.151 192.168.3.152 192.168.3.153 192.168.3.154 192.168.3.155

I purposely add IP as well as hostname as I keep using them interchangeably. I also came to know about ansible authorized_keys module that does the ssh-copy-id task:

- name: Set authorized key for user ubuntu copying it from current user
  authorized_key:
    user: ubuntu
    state: present
    key: "{{ lookup('file', lookup('env','HOME') + '/.ssh/id_rsa.pub') }}"

However, you will still need the the ssh-keyscan here. This script goes handy for ops who keep destroying their local environment and use a new one.This is available on Github: https://github.com/iamrawtion/ansible-autossh