Using ATX Port Filtering
If you want to filter on a single source or destination address, make sure the address is
TIP entered in both the Begin and End text boxes.
You can use both the source and destination address fields to filter data based on equipment vendor, since the first three bytes of a MAC address are unique to a specific vendor. For example, Sun workstations have a MAC address with the first three bytes 08:00:20. By setting a filter range of 08:00:20:00:00:00 to 08:00:20:FF:FF:FF, you could filter all Sun workstation traffic on a particular segment.
7.You can use a data field value as a filter criteria by using the Field Offset parameters. A data field value allows you to examine a packet (at a location specified by a data Field Offset) for up to 64 bytes of data that will act as the filtering criteria. To specify the portion of the packet you want examined, you indicate where you want the data field to be examined (relative to an Origin point), and enter the data value that you want to filter on (using a mask if necessary to ignore any “don’t care” bytes). To use the Field Offset parameters:
a.In the Filter Parameters section, click on the Field Offset check box to activate the Field Offset text fields.
b.Indicate whether you want the specified field offset to be exclusive or inclusive for filtering purposes.
1.) Click to activate (highlight) the Don’t Match check box if you want the packet to be filtered if it does not match the field offset value.
2.) Click to
c.Click in the Offset text field, and type in the offset — in hexadecimal — that indicates the number of bytes from the origin (discussed in the next step) at which you want to begin examining the packet’s data field. For example, an Offset of 1A indicates that you want to examine the packet starting 26 bytes after the specified origin point.
d.Click on the Origin: button to determine where you want the field offset to begin:
1.) Select MAC if you want the offset to be applied relative to the beginning of the MAC addresses; an offset of 0 indicates the start of the destination MAC address.
2.) Select IP if you want the offset to be relative to the end of the IP header; an offset of 0 indicates the portion immediately following the end of the IP header.
3.) Select SR if you want the offset to be relative to the end of the MAC header, including the Source Routing (SR) header, if present.
Editing the Port Filters Table |
