Show HN: Set up a 4 node Cassandra cluster in under 2 minutes

The tool used to ssh in parallel is http://code.google.com/p/csshx/

Nice. For OS X users, iTerm/iTerm2 "Send Input to All Tabs" mode (⌘-I) is another way to go about that.

For linux users this is the equivalent: https://github.com/duncs/clusterssh

Terminator (http://www.tenshu.net/terminator/ - not to be confused with http://software.jessies.org/terminator/) can group terms similarly on systems with gtk.

sudo brew install csshx

Note that deb and rpm packages are available, too.

How do you secure the ring? Should you use iptables so that only the other 3 hosts are allowed on the cassandra port? That seems like a bit much.

You can either allow traffic between one or more subnets, or put gossip traffic on a private network.