If you’re running Fedora 18+ type:
sudo yum install clusterssh -y

If you’re running RHEL or a RHEL clone..

Download Cluster SSH from Sourceforge

yum install gcc make kernel-devel kernel-headers perl perl-CPAN libX11-devel -y
perl -MCPAN -e shell
install Tk
install X11::Protocol

cd to your Download location and into clusterssh
make install

Run the program!
cssh server1 server2

Or create a “clusters” config file for commonly access servers and assign a “tag” (aka label for the group of servers)
mkdir ~/.clusterssh
vi ~/.clusterssh/clusters
linux user@server1 user@server2 user@server3

Run cssh using the tag contained in the clusters file with:
cssh linux