Shell Script to SSH with Password and Run Commands

When you need to run commands on multiple servers simultaneously, using a shell script can be a convenient way to automate the process. One program that makes it easy to execute ssh commands in parallel is called pssh (parallel ssh). In this article, we will explore how to use pssh to connect to multiple hosts and run commands without checking or saving host keys.

Using Pssh

Pssh provides several features that make it a valuable tool for running remote commands. For example, you can send input to all of the processes, pass a password to ssh, save the output to files, and even timeout connections. To get started with pssh, you will need to specify the hosts you want to connect to and the command you want to run.

For example, if you want to connect to two hosts, host1 and host2, and print 'hello, world' from each, you can use the following command:

```

pssh -i -H 'host1 host2' echo 'hello, world'

```

Alternative Methods

While pssh is a simple and effective way to run commands on multiple servers, there are other methods you can use as well. For example, you can use a for loop to iterate over a list of hosts and run the command manually using ssh:

```bash

for host in host1 host2; do

ssh username@$host 'pwd ls'

done

```

Security Considerations

When using pssh or other methods to execute commands on remote servers, it is important to keep security in mind. By default, pssh will save the host keys to your known hosts file, which can be a security risk if you are not careful. To disable this feature, you can add the option `-o UserKnownHostsFile=/dev/null`.

Additionally, you can also disable the host key check and automatically add the host key to the list of known hosts by adding the `StrictHostKeyChecking=no` option to your ssh command:

```

ssh -o StrictHostKeyChecking=no -l username hostname 'pwd ls'

```

Handling RSA Fingerprint Authentication

When connecting to a remote machine using ssh, you may be prompted for RSA fingerprint authentication. To handle this automatically in your shell script, you can use the following code:

```bash

#!/bin/bash

# Connect to remote machine and run command

ssh -o StrictHostKeyChecking=no -l username hostname 'pwd ls'

```

In this article, we have explored how to use pssh and other methods to execute commands on multiple servers simultaneously. By using these tools and following best practices for security, you can automate your remote command execution tasks with ease.

Shell script to ssh with password and run commands