As I know linux firewall using iptables is kenel level firewal.

How are you.
As I know linux firewall using iptables is kenel level firewal.

When we talking about string match of iptables , I'd like to know whether if
we can say linux firewall is applicaiton level firewal?
then in kernel level , open all tcp body and look at some string from of tcp
body.
when we enable string match,how about network performac?


Have a nice day.