Example 4: Mask the HTTP Server Type
Example Inc. wants to modify the HTTP Server: header so that unauthorized users and malicious code cannot use the header to identify the software that the HTTP server uses.
To modify the HTTP Server: header, you would create a rewrite action and a rewrite policy with the values in the following tables.
| Action Name | Type of Rewrite Action | Expression to choose target reference | String expression for replacement text |
|---|---|---|---|
| Action-Rewrite-Server_Mask | REPLACE | HTTP.RES.HEADER("Server") | "Web Server 1.0" |
| Policy Name | Action Name | Undefined Action | Expression |
|---|---|---|---|
| Policy-Rewrite-Server_Mask | Action-Rewrite-Server_Mask | NOREWRITE | HTTP.RES.IS_VALID |
Example commands:
> add rewrite action Action-Rewrite-Server_Mask REPLACE HTTP.RES.HEADER("Server") "\"Web Server 1.0\""
> add rewrite policy-Rewrite-Server_Mask HTTP.RES.IS_VALID Action-Rewrite-Server_Mask NOREWRITE
You would then globally bind the rewrite policy, assigning a priority of 100 and setting the Goto Priority Expression of the policy to END.
The HTTP Server: header is now modified to read “Web Server 1.0,” masking the actual HTTP server software used by the Example Inc. Web site.