Security Research Topic

[ramin_sh1]

I am going to do my master's degree research in field of network security, and my advisor has given me the opportunity to come up with a suitable subject.

There are a few general topics that I am interested in, but I haven't been able to decide on a specific topic yet. These topis look very interesting to me:

1) Intrusion Detection Systems / Personal firewall/IDS
2) Security Auditing / Vulnerability Assessment
3) Recovery Strategies (in case of network compromise)
4) Mitigating consequences of intrusions
5) Other related subjects

I am in the process of narrowing down the topics to find an interesting research-able subject, and I could really use some help here. If you can suggest any specific topic for research, please help me.

Thank you