Recently I come across a nice little nifty tool called parallel ssh (PSSH) to run a single command on multiple Linux / UNIX / BSD servers. You can easily increase your productive with this SSH IT automation tool.
More about pssh
pssh is a command line tool for executing ssh in parallel on some hosts. It specialties includes:
- Sending input to all of the processes
- Inputting a password to ssh
- Saving output to files
- IT/sysadmin task automation such as patching servers or looking for error logs
- Timing out and more
Let us see how to install and use pssh on Linux and Unix-like system.
parallel ssh (PSSH) installation
You can install pssh as per your Linux and Unix variant. Once package installed, you can get parallel versions of the openssh tools. Included in the installation:
- pssh command – Parallel ssh
- pscp command – Parallel scp
- prsync command – Parallel rsync
- pnuke command – Parallel nuke
- pslurp command – Parallel slurp
Install pssh on Debian/Ubuntu Linux
Type the following apt-get command/apt command to install pssh:
$ sudo apt install pssh
OR
$ sudo apt-get install pssh
Sample outputs:
Fig.01: Installing pssh on Debian/Ubuntu Linux
Install pssh on Apple MacOS X
First, install Homebrew on macOS and then type the following brew command:
$ brew install pssh
Sample outputs:
Fig.02: Installing pssh on MacOS Unix
Install pssh on FreeBSD unix
Type any one of the command:
# cd /usr/ports/security/pssh/ && make install clean
OR
# pkg install pssh
Sample outputs:
Fig.03: Installing pssh on FreeBSD
Install pssh on RHEL/CentOS/Fedora Linux
First turn on EPEL repo and type the following command yum command:
$ sudo yum install pssh
Sample outputs:
Fig.04: Installing pssh on RHEL/CentOS/Red Hat Enterprise Linux
Install pssh on Fedora Linux
Type the following dnf command:
$ sudo dnf install pssh
Sample outputs:
Fig.05: Installing pssh on Fedora
Install pssh on Arch Linux
Type the following command:
$ sudo pacman -S python-pip
$ pip install pssh
Set passwordless SSH using public-private key pairs
It is recommend that you set up ssh keys for automation. To generate a key pair run the ssh-keygen command:
ssh-keygen
Next transfer the public key to the remote host using the ssh-copy-id command:
ssh-copy-id user@server-ip
ssh-copy-id vivek@dellm6700
ssh-copy-id root@192.168.2.30
ssh-copy-id root@192.168.2.45
ssh-copy-id root@192.168.2.46
Test it using the ssh command:
ssh vivek@dellm6700
ssh root@192.168.2.30
See my previous tutorials SSH Public Key Based Authentication on a Linux/Unix server and set up SSH Keys on a Linux / Unix System for more information on passwordless SSH topics.
How to use pssh command
First you need to create a text file called hosts file from which pssh read hosts names. The syntax is pretty simple. Each line in the host file are of the form [user@]host[:port] and can include blank lines and comments lines beginning with “#”. Here is my sample file named ~/.pssh_hosts_files:
$ cat ~/.pssh_hosts_files
vivek@dellm6700
root@192.168.2.30
root@192.168.2.45
root@192.168.2.46
Run the date command all hosts:
$ pssh -i -h ~/.pssh_hosts_files date
Sample outputs:
[1] 18:10:10 [SUCCESS] root@192.168.2.46 Sun Feb 26 18:10:10 IST 2017 [2] 18:10:10 [SUCCESS] vivek@dellm6700 Sun Feb 26 18:10:10 IST 2017 [3] 18:10:10 [SUCCESS] root@192.168.2.45 Sun Feb 26 18:10:10 IST 2017 [4] 18:10:10 [SUCCESS] root@192.168.2.30 Sun Feb 26 18:10:10 IST 2017
Run the uptime command on each host:
$ pssh -i -h ~/.pssh_hosts_files uptime
Sample outputs:
[1] 18:11:15 [SUCCESS] root@192.168.2.45 18:11:15 up 2:29, 0 users, load average: 0.00, 0.00, 0.00 [2] 18:11:15 [SUCCESS] vivek@dellm6700 18:11:15 up 19:06, 0 users, load average: 0.13, 0.25, 0.27 [3] 18:11:15 [SUCCESS] root@192.168.2.46 18:11:15 up 1:55, 0 users, load average: 0.00, 0.00, 0.00 [4] 18:11:15 [SUCCESS] root@192.168.2.30 6:11PM up 1 day, 21:38, 0 users, load averages: 0.12, 0.14, 0.09
You can now automate common sysadmin tasks such as patching all servers:
$ pssh -h ~/.pssh_hosts_files -- sudo yum -y update
OR
$ pssh -h ~/.pssh_hosts_files -- sudo apt-get -y update
$ pssh -h ~/.pssh_hosts_files -- sudo apt-get -y upgrade
How do I use pssh to copy file to all servers?
The syntax is:
pscp -h ~/.pssh_hosts_files src dest
To copy $HOME/demo.txt to /tmp/ on all servers, enter:
$ pscp -h ~/.pssh_hosts_files $HOME/demo.txt /tmp/
Sample outputs:
[1] 18:17:35 [SUCCESS] vivek@dellm6700 [2] 18:17:35 [SUCCESS] root@192.168.2.45 [3] 18:17:35 [SUCCESS] root@192.168.2.46 [4] 18:17:35 [SUCCESS] root@192.168.2.30
Or use the prsync command for efficient copying of files:
$ prsync -h ~/.pssh_hosts_files /etc/passwd /tmp/
$ prsync -h ~/.pssh_hosts_files *.html /var/www/html/
How do I kill processes in parallel on a number of hosts?
Use the pnuke command for killing processes in parallel on a number of hosts. The syntax is:
$ pnuke -h .pssh_hosts_files process_name
kill nginx and firefox on hosts:
$ pnuke -h ~/.pssh_hosts_files firefox
$ pnuke -h ~/.pssh_hosts_files nginx
See the pssh/pscp command man pages for more information.
Conclusion
pssh is a pretty good tool for parallel SSH command execution on many servers. It quite is useful if you have 5 or 7 servers or VMs. Nevertheless, if you need to do something complicated you should look into Ansible and co. See the official site here for more info.
🐧 5 comments so far... add one ↓
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I rather use Ansible – the simplest way to automate apps and IT infrastructure :)
@nobody
Was actually going to mention ansible too
Neat utility ! I have used a similar utility in the past, called pdsh.
Not sure about other flavours, but apt installs the parallel-ssh binary and not pssh – one can always create a link, though
Thanks !
Pssh is ok, but I prefer mpssh. I can define groups of hosts and call by name.
from "violent python" #!./env/bin/python """ SSH Botnet This script logs into several different machines with ssh and sends commands to each of them in tandem Don't be a moron, please don't use this for something illegal. Usage: ssh_botnet.py ssh_botnet.py (-h | --help) ssh_botnet.py (-v | --version) Options: -h --help Show this screen. --version Show version """ import pxssh from docopt import docopt from colorama import Fore, init class Client: def __init__(self, host, user, password): self.host = host self.user = user self.password = password self.session = self.connect() def connect(self): try: ssh = pxssh.pxssh() ssh.login(self.host, self.user, self.password) return ssh except Exception, e: print Fore.RED + '[-] Error Connecting' + Fore.RESET print e def send_command(self, cmd): self.session.sendline(cmd) self.session.prompt() return self.session.before def botnet_command(command, botnet): for client in botnet: output = client.send_command(command) print Fore.GREEN + '[*] Output from ' + client.host + Fore.RESET print '[+] ' + output + '\n' def add_client(host, user, password, botnet): client = Client(host, user, password) botnet.append(client) def main(): botnet = [] add_client('10.10.10.110', 'root', 'toor', botnet) add_client('10.10.10.120', 'root', 'toor', botnet) add_client('10.10.10.130', 'root', 'toor', botnet) botnet_command('uname -v', botnet) if __name__ == '__main__': init() docopt(__doc__, version=0.1) main()