Method and systems for computer security

1. A computer-implemented method for maintaining security of a computer system, the computer comprising a memory and a central processing unit, comprising:

determining an initial system certainty value for the computer system;

providing access to a database of signatures, each signature including a signature certainty value;

receiving data;

comparing the received data with the database of signatures;

increasing the system certainty value if the received data does not match a signature in the database;

decreasing the system certainty value if the received data matches a signature in the database; and

filtering the data based on the system certainty value and the signature certainty value of a signature matching the received data.

2. The method of claim 1 , wherein the data that does not match a signature in the database is forwarded to its destination.

3. The method of claim 1 , wherein the increased or decreased certainty value becomes the initial system value.

4. The method of claim 1 , wherein the data comprises a packet of data.

5. The method of claim 1 , wherein the filtering further comprises forwarding the data if the signature certainty value is less than the system certainty value; and discarding the data if the signature certainty value is greater than the system certainty value.

6. The method of claim 5 , wherein the step of forwarding further comprises generating a message log to indicate that data matching a signature was forwarded.

7. A system for maintaining computer security, comprising:

means for determining an initial system certainty value for the computer system;

means for providing access to a database of signatures, each signature including a signature certainty value;

means for receiving data;

means for comparing the received data with the database of signatures;

means for increasing the system certainty value if the received data does not match a signature in the database;

means for decreasing the system certainty value if the received data matches a signature in the database; and

means for filtering the data based on the system certainty value and the signature certainty value of a signature matching the received data.

8. The system of claim 7 , wherein the data that does not match a signature in the database is forwarded to its destination.

9. The system of claim 7 , wherein the increased or decreased certainty value becomes the initial system value.

10. The system of claim 7 , wherein the data comprises a packet of data.

11. The system of claim 7 , wherein the means for filtering further comprises means for forwarding the data if the signature certainty value is less than the system certainty value; and discarding the data if the signature certainty value is greater than the system certainty value.

12. The system of claim 11 , wherein the means for forwarding further comprises means for generating a message log to indicate that data matching a signature was forwarded.

13. A computer recording medium including computer executable code for maintaining security of a computer system, comprising:

code for determining an initial system certainty value for the computer system;

code for providing access to a database of signatures, each signature including a signature certainty value;

code for receiving data;

code for comparing the received data with the database of signatures;

code for increasing the system certainty value if the received data does not match a signature in the database;

code for decreasing the system certainty value if the received data matches a signature in the database; and

code for filtering the data based on the system certainty value and the signature certainty value of a signature matching the received data.

14. The computer recording medium of claim 13 , wherein the data that does not match a signature in the database is forwarded to its destination.

15. The computer recording medium of claim 13 , wherein the increased or decreased certainty value becomes the initial system value.

16. The computer recording medium of claim 13 , wherein the data comprises a packet of data.

17. The computer recording medium of claim 13 , wherein the code for filtering further comprises code for forwarding the data if the signature certainty value is less than the system certainty value; and discarding the data if the signature certainty value is greater than the system certainty value.

18. The computer recording medium of claim 17 , wherein the code for forwarding further comprises code for generating a message log to indicate that data matching a signature was forwarded.

19. A system for maintaining computer security, comprising:

a computer comprising a memory and a central processing unit, the computer being operable to:

determine an initial system certainty value for the computer system;

provide access to a database of signatures, each signature including a signature certainty value;

receive data;

compare the received data with the database of signatures;

increase the system certainty value if the received data does not match a signature in the database;

decrease the system certainty value if the received data matches a signature in the database; and

filter the received data based on the system certainty value and the signature certainty value of a signature matching the received data.

20. The system of claim 19 , wherein if the received data does not match a signature in the database, the received data is forwarded to an intended destination.

21. The system of claim 19 , wherein the increased or decreased system certainty value becomes the initial system certainty value.

22. The system of claim 19 , wherein the data comprises a packet of data.

23. The system of claim 19 , wherein the computer is further operable to:

forward the received data if the signature certainty value is less than the system certainty value; and

discard the received data if the signature certainty value is greater than the system certainty value.

24. The system of claim 23 , wherein the computer is further operable to generate a message log to indicate that received data matching a signature was forwarded.