User`s guide

Packet Filtering on the OnSite
66
AlterPath OnSite Administrator’s and User’s Guide
Rules
Each chain can have one or more rules that define the following:
• The packet characteristics being filtered
The packet is checked for characteristics defined in the rule, for example,
a specific IP header, input and output interfaces, TCP flags and protocol.
• What to do when the packet characteristics match the rule
When a packet is filtered, its characteristics are compared against the
rules one-by-one. All defined characteristics must match.
Administrators can do the following to specify packet filtering:
• Add a new chain and specify rules for that chain
• Add new rules for existing chains
• Edit or delete built-in chains and rules
Add Rule and Edit Rule Options
When you add or edit a rule you can define any of the options described in the
following table.
Table 1-31: Filter Options for Packet Filtering Rules
Filter Options Description
Source IP and Mask
Destination IP and Mask
If you specify a source IP, incoming packets are filtered for
the specified IP address. If you specify a destination IP,
outgoing packets are filtered for the specified IP address.
If you fill in a source or destination mask, incoming or
outgoing packets are filtered for IP addresses from the
subnetwork in the specified netmask.