How to change password via SSH in Linux/Centos? First, you need login SSH to your Linux server, then use command passwd to change password. below example is change root password for a Centos:

-bash-3.2# su - root  - you don't need to do this if you already login ssh as root
[root @ ComfortVPS.com ~]# passwd root - usage: passwd <accountName> , passwd root means change password for accountname root
Changing password for user root.
New UNIX password:   (You should type your new password here)
Retype new UNIX password:   (You should retype your new password again)
passwd: all authentication tokens updated successfully.

Done, you have successfully changed your password!

SSH Change password Failed example:

[root @ ComfortVPS.com ~]# passwd
Changing password for user root.
New UNIX password: 
BAD PASSWORD: it is WAY too short
Retype new UNIX password: 
Sorry, passwords do not match.
New UNIX password: 
Retype new UNIX password: 
Sorry, passwords do not match.
New UNIX password: 
BAD PASSWORD: it is based on a dictionary word
Retype new UNIX password: 
Sorry, passwords do not match.
passwd: Authentication information cannot be recovered

As a general guideline, passwords should consist of 8 to 15 characters including one or more from each of following sets:

1. Lower case alphabetics
2. Upper case alphabetics
3. Digits 0 thru 9
4. Punctuation marks

You can change root password via our control area if you forget the root password which means you can't login via ssh.

Tutorial: How to change root password if I can't ssh login?