Rewriting traffic : Rewriting application layer headers
Rewriting application layer headers
The headers of HTTP and its typical payload, HTML or XML, often refer to domain names or IP addresses. For example, the Host: field in an HTTP header may be:
and the HTTP body may contain XHTML with hyperlinks:
<a href=””>
Because of this, routing a packet while applying NAT at the lower TCP/IP layers of the packet can create inconsistencies with the HTTP layer unless you also rewrite the HTTP header of the packet. For that reason, when applying application layer content-based routing, you may also need to configure content rewriting — that is, rewriting of the application layer headers.
While rewriting the application layer to support content-based routing, you can also rewrite the HTTP layer of a packet for:
aesthetic reasons (to make the URL more easily memorized by customers)
security reasons (for example, to hide the URL structure of an application that would otherwise help attackers to fingerprint a vulnerable application)
To configure content rewriting rules, go to Server Load Balancer > Content Rules > Content Rewriting Rules.