Packet Filters

Here’s a textual graph for Packet Filters in BIG-IP, showing how incoming traffic is processed and the precedence order for different components:

-----------------------------------------------------------
|                    [Incoming Traffic]                 |
-----------------------------------------------------------
                             |
                             v
-----------------------------------------------------------
|                    [Packet Filter]                    |
|   - Applies only to incoming traffic.                  |
|   - Filters based on custom expressions using          |
|     tcpdump syntax.                                   |
-----------------------------------------------------------
                             |
                             v
-----------------------------------------------------------
|              [iRule Event "FLOW_INIT"]                |
|   - Defines actions to take when traffic is detected.  |
|   - Executes after Packet Filter.                      |
-----------------------------------------------------------
                             |
                             v
-----------------------------------------------------------
|                   [TMM / AFM]                          |
|   - Traffic Management (TMM) or Advanced Firewall (AFM).|
|   - Further processes the traffic after iRule.         |
-----------------------------------------------------------

                             |
                             v
-----------------------------------------------------------
|                  [Packet Filter Logs]                 |
|   - Logs of filtered traffic are stored in:           |
|     "/var/log/pktfilter"                               |
-----------------------------------------------------------

Explanation of the Graph:

1. Incoming Traffic: The process starts with incoming traffic that is subject to filtering rules applied at various stages.

2. Packet Filter: A custom packet filter can be applied using a syntax similar to the tcpdump utility, allowing detailed and flexible control over incoming packets.

3. iRule Event "FLOW_INIT": After the packet filter, an iRule event called FLOW_INIT can be triggered. This event allows you to define specific actions to handle the traffic, providing greater flexibility in how the traffic is processed.

4. TMM / AFM: Finally, the traffic is handled by TMM (Traffic Management Microkernel) or AFM (Advanced Firewall Manager), which may perform additional processing, such as applying firewall rules or load balancing decisions.

5. Packet Filter Logs: Any traffic filtered by the Packet Filter is logged in the /var/log/pktfilter directory, allowing you to review which packets were accepted or dropped.

Precedence Order (Highest to Lowest):

• Packet Filter Rules: These rules are applied first and have the highest precedence.

• iRule Event "FLOW_INIT": This event is triggered next, after the packet filter.

• TMM / AFM: After iRules are processed, the traffic is handled by the TMM/AFM for further management.