How can I change default root password on multi server

Question

How can I change default root password (root's password was provided via CentOS installation) on multi server after I install new CentOS on all those servers.

I can use ansible tool to complete this issue but it's not work with first time root password.

How can I achieve my purpose.

Updated: I don't want login to each server to change password. I want to change root password from remote server via ssh and can complete with at least effort.

Solution:

Use ansible + below command is easiest way to change root pass on multi server.

echo "newpass" | passwd root --stdin

Answer 1

You could try to automate this using Expect. I have used Expect in the past to auto log in to routers to perform actions. Expect scripts are a bit like Macros. You can install Expect with

sudo apt-get install expect

or

yum install expect

You create an expect script and run it for each of your 100 servers (possibly via a shell script). An example basic Expect script just to give you an idea of what it does:

spawn ssh -l admin 123.111.123.11
match_max 100000
expect -ex "This system is for authorized use only.Password:"
send -- "topsecret\r"
expect -ex "Terminal type? \[xterm\]"
send -- "\r"
send -- "\n"
expect -ex "MyServer\[admin\]#"
send -- "/usr/bin/uptime \r\n"
expect -ex "MyServe\[admin\]#"

Obviously you need to change what the script should 'expect' to the actual output from your centos machines as the 'expected' stuff above is for a router. The link below is a more complicated script for setting passwords that might be helpful for you: http://surniaulula.com/2012/10/14/change-passwords-with-ssh-and-expect/

Answer 2

To change your root password after you have completed the installation, use the Root Password Tool. Type the system-config-rootpassword command in a shell prompt to launch the Root Password Tool. If you are not root, it prompts you for the root password to continue.