The url-filter anti-bypass enable command enables the abnormal HTTP packet detection function.
The undo url-filter anti-bypass enable command disables the abnormal HTTP packet detection function.
By default, the abnormal HTTP packet detection function is disabled.
When the web server has the fault tolerance mechanism or the web server is not designed based on the RFC standard of HTTP, attackers may evade URL filtering. When an attacker tampers with an HTTP packet to make the URL information extracted by the FW different from URL filtering rules, the FW will permit the abnormal HTTP packet. After the abnormal HTTP packet reaches the web server, the server can identify the requested URL. Therefore, the attacker can access the URL.
After you enable the abnormal HTTP packet detection function, the FW can detect abnormal HTTP packets, preventing attackers from evading URL filtering.