So you want to build a mainframe?

Sm0key |

Abstract

In today's article I will review how to build a minimal virtualized mainframe. This will be hosted on our lab xen cluster, in an ubuntu vm via hercules.

High level objectives:

  • Build ubuntu host
  • Install pre-reqs for mvs38 tur(n)key 4
  • Smoke test the system
  • Lessons learned

Build ubuntu host

This objective will be pretty straight forward. Ideally I would deploy a configuration mangaged template... since we are still lazy hackers... I will build it from scratch, and climb the configuration management hill another day.

I will let you figure out how you want yours built. I went with a "mostly accept the defaults" approach for this example system.

Install pre-reqs for mvs38 tur(n)key 4:

  • A tn3270 emulator
    • I will use c3270... because it's a tui
  • The virtualization environment
    • It's hercules under everthing, but it's in a turnkey solution... sortof...
    • download it here http://wotho.ethz.ch/tk4-/tk4-_v1.00.zip
    • Extract and launch it

Image of downloading the zip file.

Image of extracting and running mvs.

If everything goes well you should have this.

Image of launched mvs

Smoke test the system

Now it is time to see if what we built actually works like a mainframe.

First step is make sure our host is listening on 3270.

netstat -tlunp

Image of hercules listening on 3270

Next we will connect our emulator to our newly booted mainframe.

Image of typing c3270 command

Pro-tip:

If you do not see the logon prompt, you will need to issue the clear screen command to your 3270 emulator. In c3270 the command sequence for that is ctrl + A C. Once you have done that you should have a logon prompt like this.

Image of logon prompt ready

Now we will log in from two c3270 sessions and make sure we can use the TSO send command to message back and forth.

Image of using send command

Lessons learned

After a minimal amount of research, and consulting with my magic 8 ball; I was able to make this boot and give me an environment in which to work. There are probably more secure, more elegent, more better, or whatever ways to do this. I wasn't able to find them, and this gets the job done.

Getting ahold of z/os to build from scratch is a pain in the ass.

Next steps:

Next up we will look at instrumenting a testing environment so we can abuse some vulnerable mainframe apps.