On a linux system, which command allows you to modify settings used by the built-in packet filtering firewall?
a.
ipf
b.
iptables
c.
netwall
d.
modfire

iptables

Explanation:

On a Linux system, iptables command allows us to modify settings of the built-in packet filtering firewall.

Iptables is used to set up, maintain, inspect and update the tables of IP packet filtering rules on Linux.

For example,

# iptables -L -n -v

# iptables -I INPUT <rule number> -s <source-ip address> -j DROP

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explanation: