What do Packet-filtering firewalls Examine?

Good and perfect  answer dear Mr. Dhairyasheel Tawade:

Packet filtering or packet inspecting firewall actually checks the contents of datablocks passing through for SQL injection attacks and other malicious code.

Hi 

Packet filtering or packet inspecting firewall actually check the contents of datablocks passing through for SQL injection attacks and other malicious code.

However be aware that Packet inspection causes data corruption in Oracle and you have to turn it off in a lot of scenarios. 

Best Regards.

i agree sir

but where in the question did he ask for description in context of Databse or a packet for the databse ?

Unix Netfilter can be packet filter with extreeeeeme customizablity and added modules that inspect the packets either in switching or routing mode even at different stages like input, forwarding, output... pre routing, post routing . . . and mark the packets..

with that said, you can setup packet filter to inspect the header, source, destination, Hash, L7 Protocols, Conncection Bytes .... and hell alot of properties.

unless you mention some particular filtering software or device, it may all be a standard answer to the question.