netkit-labs-uni

What is this?

Firstly, this is a backup repo for the Netkit labs I (and another classmate) worked on in the lecture Redes de Computadoras (Computer Networks) at Universidad Nacional del Sur, Bahía Blanca, Argentina.

It is also a showcase of simple examples of Netkit labs.

What is Netkit?

According to its website, Netkit is "the poor man's way to experiment with computer networking". It is basically an environment that lets you set up virtual network devices (computers, routers, switches, etc.) that can be connected to one another, emulating a network from the real world.

About the labs showcased here

Each lab touches on a different concept and grows in complexity. From the set-up of a simple connection between two computers, to static routing, to setting up simple DNS and DHCP servers, and finally dynamic-routing using Quagga. The last lab was a form of practical exam, done without help and combining most of the topics already mentioned here.

Structure of the labs

(Little explanation based on this Netkit introductory guide by G. Di Battista et al. at the Università degli Studi Roma Tre)

In each lab you will find:

• The VMs: Represented as directories. Netkit starts a VM for each directory. The contents of this directory are mapped into the root (/) directory of the VM's file system. However, VMs can also be declared in the lab.conf file with the following statement

   machines = "pc1 pc2 pc3"
  

  that will start the VMs pc1, pc2 and pc3.

• The lab.conf file: It contains settings to the VMs that make up the lab, as well as the topology of the network that interconnects these. For example, for the definition of a collision domain

   machine[arg] = value
  

  Being arg an integer i, it defines for the machine a collision domain named as the variable value to which the interface ethi is attached. For example, the following definition

   pc1[0] = A
   
   pc2[0] = A
   pc2[1] = B
  
   pc3[0] = B
  

  Would result in the following topology:

  

• An optional lab.dep file, that declares dependencies for the start-up of the machines. For example, such a content in the lab.dep file

   pc2: pc1
   pc3: pc1 pc2
  

  states that for the pc2 to be initiated, pc1 has to have already been instantiated and running. And that for the pc3 to be instantiated, pc1 and pc2 must be already running.

• Startup and shutdown files: shell scripts that are executed inside the virtual machines at startup and shutdown respectivelly. At the startup of machine, let's say pc1, it runs the shell script pc1.startup.