Hello everyone,

I am currently building a firewall, can anyone tell me what does this really meana? "Drop all incoming packets from reserved port 0 as well as inbound traffic to port 0." What is the difference between reserved port 0 & port 0? I am very new to linux, first time working on building firewall. If anyone have time, please take a look the following scripts and give me some hints what I did so far.

# Set the default policies to DROP
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT DROP

# Permit inbound/outbound ssh packets.
iptables -A INPUT -i eth1 -p tcp --dport 22 --syn -j ACCEPT
iptables -A OUTPUT -o eth1 -p tcp --sport 22 --syn -j ACCEPT

# Permit inbound/outbound www packets.
iptables -A INPUT -i eth1 -p tcp --dport 80 --syn -j ACCEPT
iptables -A OUTPUT -o eth1 -p tcp --sport 80 --syn -j ACCEPT

# Drop inbound traffic to port 80 (http) from source ports less than 1024
iptables -A INPUT -i eth1 -p tcp --dport 80 --sport 0:1024 -j DROP

# Drop all incoming packets from reserved port 0 as well as inbound traffic to port 0

reserved means it's assignment is reserved. not http, not ssh, not telnet, not ftp, just reserved and not to be used. the two parts of the sentence are referring to inbound and outbound usage of that port number. port 0 is often used as a mechanism to summon the next ephemeral port available on the system implicitly, but that's not anything you need to care about here.