According to the text and to the knowledge concerning firewall tech...

Text 4 to answer questions 21 and 22.

1 -------Enterprise-class firewalls, such as those made by

----FORTINET, Cisco Systems and NetScreen Technologies,

----have long been marketplace commodities. Out of the box,

4 --they provide reliable, relatively easy-to-use security

----solutions. Buying some licenses from vendors can also

----provide 24/7 support and ongoing maintenance. In

7 --addition, commercial firewalls have configuration

----facilities, usually through graphical interfaces, and

----facilitated interaction with other security technologies such

10 --as SIEM, EDR, DRP, etc.

---------But commercial firewalls have a problem: many

----would say that they are expensive. That is why some IT

13 --teams consider the use of other options like open-source

----firewalls. iptables®, for example, is a freeware Linux tool

----developed by NetFilter that isn’t nearly as easy to use, but

16 --it’s quickly catching up in features and functionality.

---------iptables® firewall boasts many features normally

----found only in commercial firewalls, including packet

19 --defragmentation, rate limiting, integration of VPNs, scale

----up and scale down, packet content inspection and protocol

----state tracking.

22 -------So why don't we always use iptables® firewall instead

----of proprietary applications or devices? In addition to the

----support from manufacturers that the more traditional choice

25 --has, we can highlight iptables’® need for professional

----training, and also the need for hiring large support teams,

27--which could cost even more money in some scenarios.

Disponível em:<https://searchsecurity.techtarget.com/opinion/Commercialfirewalls-vs-Open-source-firewalls>. Acesso em 20 mar. 2021, com adaptações.