wireless: Security in Wireless Networks

Homework

Please for tuesday morning answer the following question:
Consider the network at your institution or workplace.

Which types of security has been implemented on this network? How do you protect your network from the various imaginable threats? Which types of encryption, authorisation and authentication, network protection etc. do you use to protect your network and the data that is transported on it?
On which Network layers are each of these protection methods implemented?

Extra questions (voluntary):

Which are the main threats you are trying to protect your network from?
Do you have multiple cases of the same type of security on different layers? For example, are there parts of the network where you are encrypting the same data many times? Why?
Given your knowledge about the Ethernet and TCP/IP networking models, which is the best layer to implement each of these types of security:
- Encryption?
- Authentication?
- Protection from Denial of Service attacks?

These are my bookmarks on Wireless and Security:

Huda
I liked this link - it shows how the network attackers do not have to be gurus anymore they can just use sophisticated tools
http://www.stsc.hill.af.mil/crosstalk/2000/10/allen1.gif
This link is about the top 20 vulnerabilities ( 10 for windows systems, 10 for unix systems)
http://www.sans.org/top20/