Cluster ssh

Cluster ssh is a Perl program written in  Perl in 1999-2010 by Duncan Ferguson. It is still actively maintained on Sorceforge ( Cluster SSH - Cluster Admin Via SSH ).

It is now included in Ubuntu and Debian.  Licensed like most Perl packages under GNU General Public License as published by the Free Software Foundation or the Artistic License.

Cluster ssh can help to administer multiple ssh or rsh shells simultaneously. ClusterSSH allows you to control multiple ssh or rsh sessions from a single input window. You can also configure clusters of machines for easy invocation and interact with individual terminal windows during a session.

Configuration Files

This /etc/clusters file is cluster tag database. Contains a list of tags and hostnames, in the form

<tag> [<username>@]hostname [...]

Newlines and comments (delimited with a #) are ignored.

Cluster definitions can also be added to the $HOME/.csshrc file

This /etc/csshrc file is Global configuration file, sourced by all users. Can be generated by:

sudo cssh -u > /etc/csshrc

$HOME/.csshrc

Per user configuration file. Can be generated by:

cssh -u > /etc/csshrc </tt>

To add a cluster definition to this file, use the following format

cluster_tag1 = server1 server2 user@server3
cluster_tag2 = server4 server5
clusters = cluster_tag1 cluster_tag2

Be aware of using �reserved names� and no check is currently performed for them.

Using Cluster SSH

If you want to perform the same command on the three servers one, two, & three use the following command

sudo cssh one two three

This will open three consoles, one for each server, over an ssh connection, and one little console to type your command.

NEWS CONTENTS

• 210227 : Cluster SSH by Dan Stoner ( January 24 2012 , thatlinuxbox.com )

Old News ;-)

ssh on multiple servers Using cluster ssh

Cluster SSH opens terminal windows with connections to specified hosts and an administration console. Any text typed into the administration console is replicated to all other connected and active windows. This tool is intended for, but not limited to, cluster administration where the same configuration or commands must be run on each node within the cluster. Performing these commands all at once via this tool ensures all nodes are kept in sync.

Introduction

What is ClusterSSH and what is it used for?

Ever had to make the same change on more than one Linux/unix server? Find it annoyingly painful to keep repeating the exact same commands again and again and again?

This tool addresses exactly this problem. You run a utility (cssh) providing a number of server names as parameters, and then xterms opens up to each server with an extra "console" window. Anything typed into the console is replicated into each server window (so, for examples, you can edit the same file on N machines at the same time, or run the same commands with the same parameters across those servers).

It is also possible to type into the server windows directly, or temporarily disable replication to one or more of the servers through the "Hosts" menu.

Difference between ClusterSSH and "cssh"

The utility itself is called "cssh". The project name is ClusterSSH. The project is not called "cssh" because when the project was first registered on SourceForge a project already existed using that name ("C sharp" unix shell).

Install cluster ssh on debian

#apt-get install clusterssh

Configuration Files

This /etc/clusters file is cluster tag database. Contains a list of tags and hostnames, in the form

<tag> [<username>@]hostname [...]

Newlines and comments (delimited with a #) are ignored.

Cluster definitions can also be added to the $HOME/.csshrc file

This /etc/csshrc file is Global configuration file, sourced by all users. Can be generated by:

cssh -u > /etc/csshrc

$HOME/.csshrc

Per user configuration file. Can be generated by:

cssh -u > /etc/csshrc</tt>

To add a cluster definition to this file, use the following format

cluster_tag1 = server1 server2 user@server3
cluster_tag2 = server4 server5
clusters = cluster_tag1 cluster_tag2

Be aware of using "reserved names" and no check is currently performed for them.

Using Cluster SSH

If you want to perform the same command on the three servers one, two, & three use the following command

# cssh one two three

This will open three consoles, one for each server, over an ssh connection, and one little console to type your command.

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5. How to add a Disclaimer To Outgoing Emails in Postfix

Cluster SSH by Dan Stoner

January 24 2012 | thatlinuxbox.com

01

ClusterSSH is a nice tool for manipulating multiple *nix machines simultaneously. For example, if I want to run some commands on two Linux machines named server1 and server2, I could:

# cssh server1 server2

And I will get two xterm windows that I can control simultaneously by typing into the cssh command window. Since cssh will send keystrokes to both servers, any series of commands can be run, including editing files, etc. I have found that my daily patterns of behavior make cssh preferable to similar tools such as pdsh. Also, cssh uses very similar options syntax to the ssh command, so I don't have to remember different options (I frequently use -l and -p).

I might want to tail the logs on all of the machines in the cluster, but then focus in on one particular machine after I have identified a particular cluster node of interest. Similarly, I might work out a long command line on a single node before running it on the rest of the machines via the cssh command window.

In Debian and Ubuntu, cssh can be installed with:

# sudo apt-get install clusterssh

Cluster SSH is also available for Mac OS X (http://code.google.com/p/csshx/).

A clusterssh package seems to be working its way into Red Hat flavors via Extras or 3rd party repos such as rpmforge.

After running cssh for the first time, you will have a .csshrc file in your home directory. This file can be tweaked in various ways to make connecting to groups of machines easier. To save a group of machines into a list that you can re-use, cssh can use a plain text cluster file.

To use a cluster file:

Step 1: Create a file named .clusters that contains your list of server groups. The format of the file is just a friendly name for a cluster followed by all of the machines that you want to connect as part of that cluster, with white space in between.

For example, my .clusters file looks something like:

prod_servers server1 server2 server3 server4

test_servers testserver1 testserver2

Step 2: Modify .csshrc to tell cssh to use the clusters file.

extra_cluster_file=~/.clusters

Now that I have a cluster defined, I can connect to my prod servers all at once by running:

# cssh prod_servers

In my example case, this would open four xterms to the four servers. If I type into the cssh command window the text will go to all four xterms. If I only want to run a command on one of them, I just click on the particular xterm to give it focus and it behaves like a normal individual xterm.

I have found cssh to be a valuable utility in my sysadmin toolbox.

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