Lab 13: Application Serving & OSI

The Remote Calculator Server

If you are working at home you will need to be running your own Calculator server on your home network to complete this exercise. Follow the instructions with the CD to start up the NPS servers and note the IP address of that machine You will need to download the JAR file for the Calculator server from the unit home page as it is not ready at the time of production of the NPS CD.

The server is running on "krause" and can be accessed using the Remote Arithmetic icon on your desktop. The client and server are written in Java.

Run NetXRay and capture traffic between the client and server when using the RPC and the CORBA server.
You will have to design filters to view the interesting packets. The significant "conversation" between the client and the server is in the form of TCP "data". As in previous labs create a data pattern filter that selects packets with ACK and PSH set ( 0x18 )
Note that there are no useful decodes in these captures - NetXRay does not understand how to decode CORBA traffic and, more obviously, it does not understand how decode the specific packets that my RPC client sends to my RPC server. This means that the real conversation between server and client shows up simply as TCP "data" .
Try doing differerent sums and see if you can identify the fields in a request ( and maybe reply ) packet. Integers are send as 4 (big-endian) bytes. This is an XDR representation.
Do the equivalent investigation of the CORBA connection


NetSim is a distributed application written using Java and CORBA. There is a CORBA server running on "web" and clients running on multiple machines.

Run NetSim at two stations and try to answer the following:

What is the name of the application on the NetSim server?
What procedure names can you identify?
The interactions are between client/server and also client/client. Try to draw a protocol interaction diagram showing when the various interactions take place as you establish and use a NetSim network