how to insall sshpass
Centos Linux Ubuntu

SSH password automation in Linux with sshpass

In this blog I tried to give some explanation and example of SSH password automation in Linux with sshpass.

What is sshpass in linux?

The sshpass utility is designed to run SSH using the keyboard-interactive password authentication mode, but in a non-interactive way.

SSH uses direct TTY access to ensure that the password is indeed issued by an interactive keyboard user. sshpass runs SSH in a dedicated TTY, fooling SSH into thinking it is getting the password from an interactive user.

Install sshpass on linux

You can install sshpass with this simple command:

# yum install sshpass

Use sshpass

Specify the command you want to run after the sshpass options. Typically, the command is ssh with arguments, but it can also be any other command. The SSH password prompt is, however, currently hardcoded into sshpass.

The synopsis for the sshpass command is described below:

sshpass [-ffilename|-dnum|-ppassword|-e] [options] command arguments

Where:

-ppassword
    The password is given on the command line. 
-ffilename
    The password is the first line of the file filename. 
-dnumber
    number is a file descriptor inherited by sshpass from the runner. The password is read from the open file descriptor. 
-e
    The password is taken from the environment variable "SSHPASS".

Examples

To better understand the value and use of sshpass, let’s look at some examples with several different utilities, including SSH, Rsync, Scp, and GPG.

Example 1: SSH

Use sshpass to log into a remote server by using SSH. Let’s assume the password is!4u2tryhack. Below are several ways to use the sshpass options.

A. Use the -p (this is considered the least secure choice and shouldn’t be used):

$ sshpass -p !4u2tryhack ssh username@host.example.com

The -p option looks like this when used in a shell script:

$ sshpass -p !4u2tryhack ssh -o StrictHostKeyChecking=no username@host.example.com

B. Use the -f option (the password should be the first line of the filename):

$ echo '!4u2tryhack' >pass_file
$ chmod 0400 pass_file
$ sshpass -f pass_file ssh username@host.example.com

Here is the -f option when used in shell script:

$ sshpass -f pass_file ssh -o StrictHostKeyChecking=no username@host.example.com

C. Use the -e option (the password should be the first line of the filename):

$ SSHPASS='!4u2tryhack' sshpass -e ssh username@host.example.com

The -e option when used in shell script looks like this:

$ SSHPASS='!4u2tryhack' sshpass -e ssh -o StrictHostKeyChecking=no username@host.example.com

Example 2: Rsync

Use sshpass with rsync:

$ SSHPASS='!4u2tryhack' rsync --rsh="sshpass -e ssh -l username" /custom/ host.example.com:/opt/custom/ 

The above uses the -e option, which passes the password to the environment variable SSHPASS

We can use the -f switch like this:

$ rsync --rsh="sshpass -f pass_file ssh -l username" /custom/ host.example.com:/opt/custom/

Example 3: Scp

Use sshpass with scp:

$ scp -r /var/www/html/example.com --rsh="sshpass -f pass_file ssh -l user" host.example.com:/var/www/html

Example 4: GPG

You can also use sshpass with a GPG-encrypted file. When the -f switch is used, the reference file is in plaintext. Let’s see how we can encrypt a file with GPG and use it.

First, create a file as follows:

$ echo '!4u2tryhack' > .sshpasswd

Next, encrypt the file using the gpg command:

$ gpg -c .sshpasswd

Remove the file which contains the plaintext:

$ rm .sshpasswd

Finally, use it as follows:

$ gpg -d -q .sshpassword.gpg > pass_file; sshpass -f pass_file ssh user@srv1.example.com

Wrap up

sshpass is a simple tool that can be of great help to sysadmins. This doesn’t, by any means, override the most secure form of SSH authentication, which is public-key authentication. However, sshpass can also be added to the sysadmin toolbox.

This is all about the SSH password automation in Linux with sshpass. If you want to add some thing please comment.

This post is publish by Evans Amoany (Sudoer). If you need more info here in referral link.

Leave a Reply

Your email address will not be published. Required fields are marked *