Chapter 21 Appendix A: Operation Commands
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Command: >set filter
Syntax: set filter direction list_name interface
Explanation: Sets packet filtering on incoming and/or outgoing connections on specific interface. Before
setting the filter, please add filter entries first.
Note: if the packet does not match any entry in the list, the packet will be discarded.
Parameters: direction the packet flow direction to be filtered
list_name the name of the list to be set
interface the name of the interface to be set up for the packet filtering
Command: >set lan1 ip
Syntax: set lan1 ip ip_addr net_mask
Explanation: Set the LAN port’s IP address.
Parameters: ip_addr IP address of the LAN port
net_mask subnet mask of the LAN port
Regarding IP Address Classes and Their Formats:
Because networks vary in size, there are four different address types to consider. The types are:
Class A addresses are for large networks with many devices.
Class B addresses are for medium-sized networks.
Class C addresses are for small networks (fewer than 256 devices).
Class D addresses are multicast addresses.
The first few bits of each IP address indicate which address type is being used. it is using. The address
structures look like this:
Class A
0 Network (7 bits) Local address (24 bits)
Class B
10 Network (14 bits) Local address (16 bits)
Class C
110 Network (21 bits) Local address (8 bits)
Class D
1110 Multicast address (28 bits)
An IP address is usually expressed as four decimal numbers, each of which represents eight bits. The
decimal numbers are separated by periods. This is known as dotted quad notation. For Class A IP
addresses, the numbers would represent "network.local.local.local"; for a Class C IP address, they would
represent "network.network.network.local".
Regarding Subnet Mask:
When a packet arrives at an organization's gateway or connection point with its unique network number, it
can be routed within the organization's internal gateways using the subnet number as well. The router knows
which bits to look at by referencing the subnet mask. The mask is simply a screen of numbers that tells
you which numbers to look at underneath. In a binary mask, a "1" over a number means that the router
should refer to the number underneath. Similarly a “0” means don’t refer to the number underneath.look. A
mask saves the router fromlhalvling to process an entire 32 bit address. Subnet masking allows routers to
move packets on more quickly.
Command: >set lan1 routing
Syntax: set lan1 routingprotocol
Explanation: Set routing protocol of LAN1.
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