SSH (Secure Shell) is a powerful command-line tool that allows you to securely manage your dedicated server from a remote location. If you have more than one server, however, it can become tedious to have to SSH into each one and make identical changes.
Cluster SSH is a software utility that gives you the ability to simultaneously open SSH terminals, connect to multiple servers, and run identical commands, essentially keeping the servers in sync. This is particularly useful for server clusters where the individual servers are actually nodes for the larger system.
With Cluster SSH, you will have an extra console that controls all of the other terminal windows. If you ever need to run a command on only one of the servers, just type directly into that server’s window or temporarily disable replication.
The command to use Cluster SSH is “cssh”. To connect to three servers, for example, you would enter cssh followed by the hostnames of the three servers:
cssh server1 server2 server3
Three console windows will open, one for each server, and then a smaller console window will open where you can type the global commands. It works by controlling xterm windows in a Linux/Unix environment. Therefore, Cluster SSH is not available for Windows, except through virtualization. It does, however, support Linux, BSD, Solaris, and Mac OS X. Cluster SSH is free and open source software, available for free download.