First lessons for foreign students
Network communication is critically important. You may think it is always provided by some specialists. It is partly true but sometimes you cannot ask for their helps. You should become able to take care of some simple troubles by yourselves, especially if they happen at or near your desk. To do so, you should learn and understand some basic keywords and ideas about LAN and internet.
Here I give you some exercises without instructions or answers. I want you to struggle and find the solutions by yourself. Such experiences may be time-consuming and cumbersome, but eventually they are much more educative, because they remain in your memory with many other knowledges gained during your searching processes with many trials and errors.
- Explain the following terms and their relationships to each other:
- IP address, global IP address, and private IP address
- domain name and host name
- router, gateway, and network switch (hub)
- MAC address
- subnet mask
- Find the IP address, subnet mask, gateway, and DNS in your own desktop computer.
- Find the router and network switch (hub) in your office. How is your PC wired to them?
- Explain the following terms and their relationships to each other
- Make a pair with your friend.
- Install ssh server in both Linux PCs of yours and the friend.
- Try to log-in to each other's PC via LAN using ssh command.
- Try to send a file to each other's computer via LAN using scp command.
- By making use of SSH private key (RSA or DSA), configure the PCs so that you can log-in to your friend's PC without password.
- Check SSH access log in your computer and find the trace of the access by your friend.
- After above all exercise, remove sshd and the log-in account of each other (for security).
A basic knowledges and skills of math and physics help you read papers and get ideas.
- Suppose x is a digital number which describes surface reflectance (r) of an object. The value of x ranges from 0 to 255, but 0 is used for NULL and 255 is used for overflow. If x=1 corresponds to y=0.0, and x=254 corresponds to y=1.0, derive an equation which translate x value to y value.
- Suppose x and y are related to each other by a linear function like y=ax+b. If x=x_0 corresponds to y=y_0, while x=x_1 correnponds to y=y_1, derive the linear function which translate x value to y value.
Whenever you handle geographical data including satellite data, you may want to display, overlay, pickup, measure, etc. QGIS is a most suitable software for it. Learn how to use QGIS!