# l3-l4-forwarding-in-xdp

L3/L4 XDP-based forwarding system for BIRD and Linux routers for achieving line-speed forwarding.

This project implements Layer 3 (IP) and Layer 4 (TCP/UDP) packet forwarding using eBPF and XDP (eXpress Data Path). It leverages the high-performance capabilities of XDP for efficient packet processing in the Linux kernel with bird or FRR.

**Note:** `xdp-tools` is highly recommended for loading and managing the XDP program.

## Installation

Install the necessary dependencies using `apt`:

```bash
apt update
apt install clang llvm libbpf-dev libelf-dev pkg-config make git bpftool xdp-tools
```

## Compilation

Compile the eBPF program from the source code:

```bash
clang -O2 -g -Wall -target bpf -D__BPF_TRACING__  -I /usr/src/linux-headers-$(uname -r)/include   -c main.c -o main.o
```

This will generate the object file `main.o` which contains the compiled eBPF code.

## Usage

### Attach to the Interface

Load the XDP program onto a network interface (e.g., `eth0`):

```bash
xdp-loader load eth0 ./main.o
```

Check the status of loaded XDP programs:

```bash
xdp-loader status
```

### Monitoring and Debugging

Use `bpftool` to inspect maps and statistics:

```bash
bpftool map show
```

These commands will display information about the eBPF maps used in the program, such as flow statistics.

## Unloading the Program

To unload the XDP program from the interface:

```bash
xdp-loader unload eth0
```