3Com 4007, Implementation Manual, Page: 15 / 684

15
P
ACKET
F
ILTERING
Packet Filtering Overview 306
What Can You Filter? 306
When Is a Filter Applied? — Paths 307
Input Packet Filtering: Receive Path 307
Output Packet Filtering: Transmit Path 307
Internal Packet Filtering: Receive Internal Path 307
Path Assignment 308
Key Concepts 309
Standard Packet Filters 309
Custom Packet Filters 310
Important Considerations 311
Managing Packet Filters 311
Tools for Writing Filters 313
ASCII Text Editor 313
Built-in Line Editor 313
Web Management Filter Builder Tool 315
Downloading Custom Packet Filters 317
Setting Up Your Environment 317
Loading a Custom Filter on the Switch 4007 318
The Packet Filtering Language 319
Principles for Writing a Custom Filter 319
How the Packet Filter Language Works 319
Procedure for Writing a Custom Filter 320
Packet Filter Opcodes 322
Implementing Sequential Tests in a Packet Filter 329
Common Syntax Errors 331
Custom Packet Filter Examples 333
Destination Address Filter 333
Source Address Filter 333
Length Filter 333
Type Filter 334
Ethernet Type IPX and Multicast Filter 334
Multiple Destination Address Filter 334
Source Address and Type Filter 335
Accept XNS or IP Filter 335
XNS Routing Filter 335