Chapter Nine: Advanced Installations | IP filters 128 |
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IP filters
IP filtering provides you with the means to implement customized security, usage, and cost control measures.
How filtering works
Filters are defined in a stack. Up to 8 filters can be combined together to obtain sophisticated results. Data cascades through the filter stack as follows:
Input to filter stack
Are any filters
active?
Yes
No | Bypass filter stack |
Send all data into filter stack
Filter #1
Apply filter Data that matches |
| Action | Forward | |
conditions |
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Data that does not match
Drop
Filter #2
Discard
Apply filter Data that matches |
| Action | Forward | |
conditions |
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Data that does not match
Drop
Discard
Filter #8
Apply filter Data that matches conditions
Data that does not match
Action | Forward |
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Drop
Discard
Discard
Output from filter stack
Each profile has its own filter stack. However, note that once any filter is activated, all incoming and
outgoing data passes through the filter stack. By default, the DIVA LAN ISDN Modem defines three filters. This means, unless you turn these filters off, all incoming and outgoing data passes through the filter stack.
Note More sophisticated filters can be defined using the command line interface. See Chapter Ten for more information.
