Ubuntu run xdp drop world

最新推荐文章于 2024-08-20 18:38:00 发布

RafaelRaffaella

最新推荐文章于 2024-08-20 18:38:00 发布

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分类专栏： linux 文章标签： ubuntu linux 服务器

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本文介绍了如何在不升级Linux内核的情况下，通过BPF（BerkeleyPacketFilter）在XDP（eXpressDataPath）中编写自定义规则，如丢弃所有网络数据包。文章涉及的命令和工具包括apt安装特定包、BPF宏定义、编译及验证过程。

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sudo apt install clang llvm libelf-dev libpcap-dev gcc-multilib build-essential
# kernal 升级内核，不想升级，可以跳过
sudo apt install linux-tools-$(uname -r)
sudo apt install linux-headers-$(uname -r)
# tool
sudo apt install linux-tools-common linux-tools-generic
sudo apt install tcpdump

vim xdp-drop-world.c
...
#include <linux/bpf.h>

/*
 * Comments from Linux Kernel:
 * Helper macro to place programs, maps, license in
 * different sections in elf_bpf file. Section names
 * are interpreted by elf_bpf loader.
 * End of comments

 * You can either use the helper header file below
 * so that you don't need to define it yourself:
 * #include <bpf/bpf_helpers.h> 
 */
#define SEC(NAME) __attribute__((section(NAME), used))

SEC("xdp")
int xdp_drop_the_world(struct xdp_md *ctx) {
    // drop everything
	// 意思是无论什么网络数据包，都drop丢弃掉
    return XDP_DROP;
}

char _license[] SEC("license") = "GPL";
...
clang -O2 -target bpf -c xdp-drop-world.c -o xdp-drop-world.o
readelf -a xdp-drop-world.o
llvm-objdump -S xdp-drop-world.o
ip a
ip link set dev ens33 xdp obj xdp-drop-world.o sec xdp verbose
// now your pc said goodbye world
// come back command
ip link set dev ens33 xdp off