Explanation/Reference:
Explanation:
A: You need to specify the table and the chain for each firewall rule you create. There is an exception:
Most rules are related to filtering, so iptables assumes that any chain that's defined without an associated table will be a part of the filter table. The filter table is therefore the default.
D: Nat Network Address Translation
PREROUTING
Address translation occurs before routing. Facilitates the transformation of the destination IP address to be compatible with the firewall's routing table. Used with NAT of the destination IP address, also known as destination NAT or DNAT.
POSTROUTING
Address translation occurs after routing. This implies that there was no need to modify the destination IP address of the packet as in pre-routing. Used with NAT of the source IP address using either one-to-one or many-to-one NAT. This is known as source NAT, or SNAT.
OUTPUT
Network address translation for packets generated by the firewall. (Rarely used in SOHO environments) F: There are three tables in total. The first is the mangle table which is responsible for the alteration of quality of service bits in the TCP header.
The second table is the filter queue which is responsible for packet filtering. It has three built-in chains in which you can place your firewall policy rules.
The third table is the nat queue which is responsible for network address translation.