Introduction : Packet Filtering : Structure of IP filtering

Structure of IP filtering
The Firewall Configuration form in the Web Manager is structured on two levels:
Chain
A chain is a named profile that includes one or more rules defining either a set of characteristics to look for in a packet or what to do with any packet having all the defined characteristics.
The console server filter table contains a number of built-in chains, each referenced according to the packet type they handle. As defined in the rules for the default chains, all input and output packets and packets being forwarded are accepted.
Rule
Each chain can have one or more rules that define either the packet characteristics being filtered or what to do when the packet matches the rule.
Each filtered packet characteristic is compared against the rules. All defined characteristics must match. If no rules are found then the default action for that chain is applied.
Administrators can: