VIDEOS 》 Linux Kernel struct iphdr data-structure

Download this episode my entire kernel module sample code, make file, clean script HERE. And here is the same source code for a quick reference.

/* ip_send_check.c
 * Author: Kiran Kankipati
 * Updated: 15-feb-2017
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/module.h> 
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/skbuff.h>  
#include <linux/udp.h>
#include <linux/ip.h>
#include <linux/in.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/inet.h>
#include <linux/inetdevice.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/if_arp.h>
#include <linux/icmp.h>
#include <linux/netlink.h>
#include <linux/mroute.h>
#include <net/checksum.h>
#include <net/inet_ecn.h>
#include <net/xfrm.h>
#include <net/route.h>
#include <net/sock.h>
#include <net/ip.h>
#include <net/tcp.h>
#include <net/arp.h>
#include <net/udp.h>
#include <net/icmp.h>
#include <net/inetpeer.h>
#include <net/protocol.h>
#include <net/flow.h>
#include <asm/types.h>

static struct nf_hook_ops nfho_post_routing;

unsigned int post_routing_hook_func(void *priv, struct sk_buff *skb, const struct nf_hook_state *state)
	struct iphdr *iph = ip_hdr(skb);

	/*------ test ip checksum --------*/
	//iph->check = 0;
	return NF_ACCEPT; //this will accept the packet

static int hello_init(void)
	//Packet TX
	nfho_post_routing.hook = post_routing_hook_func;
	nfho_post_routing.hooknum = NF_INET_POST_ROUTING; = PF_INET;
	nfho_post_routing.priority = NF_IP_PRI_FIRST;

	return 0;

static void hello_exit(void) { nf_unregister_hook(&nfho_post_routing); }


Refer: Kernel Doc printk-formats.txt -

Here is the screenshot of my Sample Example Code discussed in the video above:

struct iphdr data-structure -
sk_buff to iphdr APIs -
Definitions for the IP module -

And here is the copy paste of struct iphdr data-structure (/include/uapi/linux/ip.h) from the Kernel-source version 4.13 for quick reference:

struct iphdr {
	__u8	ihl:4,
#elif defined (__BIG_ENDIAN_BITFIELD)
	__u8	version:4,
#error	"Please fix "
	__u8	tos;
	__be16	tot_len;
	__be16	id;
	__be16	frag_off;
	__u8	ttl;
	__u8	protocol;
	__sum16	check;
	__be32	saddr;
	__be32	daddr;
	/*The options start here. */

Suggested Topics:

Video Episodes :: Linux Kernel programming

Linux ioctl() API interface ↗
Thursday' 09-Jul-2020
Watch detailed videos and read topics on Linux Kernel Programming and Linux ioctl() API interface

Linux Kernel Architecture ↗
Thursday' 09-Jul-2020

Linux Kernel Programming - Device Drivers ↗
Thursday' 09-Jul-2020
Watch detailed videos and read topics on Linux Kernel Programming - Device Drivers

Linux Kernel - Containers and Namespaces ↗
Thursday' 09-Jul-2020

Linux Kernel FileSystems Subsystem ↗
Thursday' 09-Jul-2020

Linux Kernel /proc Interface ↗
Thursday' 09-Jul-2020

Linux Kernel Compilation ↗
Thursday' 09-Jul-2020

Linux Operating System - User-space Processes ↗
Thursday' 09-Jul-2020

Linux Kernel Programming ↗
Thursday' 09-Jul-2020

Join The Linux Channel :: Facebook Group ↗

Visit The Linux Channel :: on Youtube ↗

Join a course:

💎 Linux, Kernel, Networking and Device Drivers: PDF Brochure
💎 PhD or equivalent (or Post Doctoral) looking for assistance: Details
💎 ... or unlimited life-time mentorship: Details

💗 Help shape the future: Sponsor/Donate

Tópicos recomendados:
Featured Video:
Assista no Youtube - [97//0] B.E and M.E Final Year Projects - Execute your project ↗

Roadmap - How to become Linux Kernel Developer - Device Drivers Programmer and a Systems Software Expert ↗
Thursday' 09-Jul-2020
Many viewers and even sometimes my students ask me how I can become a kernel programmer or just device driver developer and so on. So I shot this video (and an add-on video) where I summarized steps and a roadmap to become a full-fledged Linux Kernel Developer.

Compiling a C Compiler with a C Compilter | Compile gcc with gcc ↗
Thursday' 09-Jul-2020
The fundamental aspect of a programming language compiler is to translate code written from language to other. But most commonly compilers will compile code written in high-level human friendly language such as C, C++, Java, etc. to native CPU architecture specific (machine understandable) binary code which is nothing but sequence of CPU instructions. Hence if we see that way we should able to compile gcc Compiler source code with a gcc Compiler binary.

AT&T Archives: The UNIX Operating System ↗
Thursday' 09-Jul-2020

CEO, CTO Talk ↗
Thursday' 09-Jul-2020

Programming Language Performance and Overheads ↗
Thursday' 09-Jul-2020
A detailed Youtube video series of various programming language performance and overheads - a big picture

Arduino UNO - RO Water Purifier Controller ↗
Thursday' 09-Jul-2020
Here is a Youtube VLOG of my DIY RO Water Purifier Controller done via Arduino UNO. I want the Arduino UNO to control the RO pump, so that it pumps for a specific duration and stops automatically. This is done via Opto-isolated 4 Channel 5V 10A Relay Board meant for Arduino UNO, Raspberry Pi or similar SoC boards which offers GPIO pins. To this relay I have connected the RO water purifier booster pump which works at 24V DC connected via 220V AC to 24V DC power supply adaptar. I have also connected a small active 5V buzzer to notify the progress and completion as it fills the tank/canister.

CYRIL INGÉNIERIE - CoreFreq Linux CPU monitoring software ↗
Thursday' 09-Jul-2020

Nmap Network Scanning ↗
Thursday' 09-Jul-2020

Telnet installation and remote access ↗
Thursday' 09-Jul-2020

Linux Kernel Network Programming - Transport Layer L4 TCP/UDP Registration - Protocol APIs ↗
Thursday' 09-Jul-2020

Trending Video:
Assista no Youtube - [4063//0] 311 - Setting up a Linux Container with LXC on Ubuntu - Live Demo ↗

Linux Software Development and Tools ↗
Thursday' 09-Jul-2020

Recommended Video:
Assista no Youtube - [18722//0] How to start Open-Source Project - Episode1 #TheLinuxChannel #KiranKankipti ↗