Packet filter firewall rules

Refer to the firewall script handout. Please write and turn in a brief (couple of lines each) descriptive statement of what motivated 1) lines 5-7 collectively, 2) lines 12-13 collectively, 3) line 21, and 4) line 24. What was the person who wrote them seeking to accomplish? For example, "...to block incoming web requests" or "to permit outgoing ping and other icmp packets from the local network," or whatever you can divine by looking at the syntax of the lines in light of my description of firewall operation. See the  packet filter firewall presentation ("Networks: firewalls" link on homepage). In particular, the slide entitled "What a Rule says" and the 2 that follow it should help you interpret the "clauses" in the ipchains commands. While ipchains is a particular interface to a particular implementation of a packet filter firewall, the motivating objectives (i.e., the answers to this assignment) are universal starting points to working with any packet filter firewall.