Case 1: Basic management of iptables
Case 2: Filter filtering and forwarding control
Case 3: Firewall extension rules
Case 4: Configuring SNAT to achieve shared Internet access

1 Case 1: Basic iptables management

1.1 Questions
This case requires practicing the use of iptables commands and completing the following tasks as required:

• Close firewalld and enable iptables service
• View firewall rules
• Append, insert firewall rules
• Delete, clear firewall rules

1.2 Solution
The iptables firewall has 4 tables and 5 chains. The 4 tables are the filter table, the nat table, the raw table, and the mangle table. The 5 chains are the INPUT chain, the OUTPUT chain, the FORWARD chain, the PREROUTING chain, and the POSTROUTING chain..Firewall rules are required to be written in a specific chain of a specific table, and the effect is shown in Figure-1.

Figure-1

1.3 Steps
The following steps are required to implement this case.

Step 1: Close firewalld and start iptables service

1) Shut down the firewalld server

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