Fix: Tracing with eBPF tracepoint "netif_receive_skb" for multiple NICs

 When tracing with eBPF tracepoints like "netif_receive_skb" for multiple NICs, you can leverage eBPF's flexibility to filter packets based on the NIC's name or any other relevant attribute. Here's a general approach:


1. **Identify the NICs**: You need to know the names of the NICs you want to trace. You can list the NICs on your system using a command like `ip link` or `ifconfig`.


2. **Filter Packets by NIC Name**: In your eBPF program, you can filter packets based on the NIC's name using the `ifindex` attribute provided by the tracepoint. Here's an example eBPF program to filter packets from a specific NIC:


   ```c

   #include <linux/if.h>

   #include <linux/skbuff.h>

   

   SEC("netif/receive_skb")

   int netif_receive_skb(struct __sk_buff *skb) {

       struct net_device *dev;

   

       // Get the network device associated with the packet

       dev = bpf_get_current_task()->real_dev;

   

       // Filter packets from a specific NIC by name

       if (dev && (bpf_ntohs(skb->ifindex) == if_nametoindex("eth0"))) {

           // Your tracing logic here

       }

   

       return 0;

   }

   ```


   In the example above, the `ifindex` attribute is checked against the `if_nametoindex` function, which maps the NIC name to its index. You can modify this code to trace packets from multiple NICs by adding more `if` conditions.


3. **Compile and Load the eBPF Program**: Compile the eBPF program and load it using the `bpftool` or similar tools.


4. **Attach to Tracepoint**: Use the `bpftool` command to attach the eBPF program to the "netif_receive_skb" tracepoint.


5. **Inspect Trace Data**: After attaching the eBPF program, you can use tools like `perf`, `bpftool`, or `bpftrace` to inspect the trace data and analyze packets received by the specified NICs.


Make sure to adapt the eBPF program to your specific use case and add additional filtering logic as needed. This approach allows you to trace packets for multiple NICs based on their names while using a single eBPF program.

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