Optimized Example
In the example that follows, the shell variables and kernel-level protection services are the same as those listed in the example in Chapter 4. One new variable is declared, USER_CHAINS, which contains the names of all the user-defined chains used in the script.
User-Defined Chains in the Script
The chains are listed here:
tcp-state-flags— Contains the rules to check for invalid TCP state flag combinations.
connection-tracking— Contains the rules to check for state-related matches, INVALID, ESTABLISHED, and RELATED.
source-address-check— Contains the rules to check for illegal source addresses.
destination-address-check— Contains the rules to check for illegal destination addresses.
EXT-input— Contains the interface-specific ...
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