On the same trip to India, I found myself in the position of delivering a training session to a room with incredibly varied backgrounds and skill levels. Some folks had never edited a file on the Unix command line before. Others just wanted to know where MPICH was installed. This set of slides goes from [...]
I recently took a trip to Kolkata, India to train users and administrators of an Apple / Inquiry compute cluster there. The slides I developed for that trip may be of general interest, and so I’m sharing them here. The intent of these slides is to provide an overview of the administrative tools and systems [...]
Apple provides a GUI for setting up the IP address and authentication information on the LOM. The problem, for me, with using a GUI for something like this is that it’s nearly impossible to script and automate. When I’m setting up a cluster of even a dozen nodes, going through a remote desktop to a GUI becomes intolerable in a hurry. This post shares my recipe for getting the LOM ports on the network and accessible, using only the command line.
The problem addressed here is the same as the previous two, except that the remote administrator won’t open up *any* ports in their firewall. Machines on the customer’s network can connect out onto the internet, but there is no direct way to connect to them from out here. This post describes how to set up a pair of tunnels that meet in the middle, allowing me access to machines that don’t even have a public IP address.
In a previous post I described how and why one might set up a very simple ssh tunnel in order to access a web server or a remote desktop server on a machine with a restrictive firewall. This post goes one step deeper, showing how to chain tunnels together.
A basic introduction to ssh tunnels: As a first puzzle, assume that a friendly administrator gave me an ssh account on her web server. However, her organization’s security scheme only allows me to get to port 22. I can ssh in, but I can’t really debug some problem with the web browser because port 80 is still blocked. Assume as well that we’ve already called up the network administrator, who offered to think about it – laughed maniacally – and hung up on us.
Here is a trick I use a couple of times a month to get finicky compute nodes in a Apple compute clusters to correctly bind to their LDAP / Open Directory master. This started working as of OS X 10.4, and to my knowledge it still works as of OS X 10.6.1. Bioteam uses a [...]
