Subject: Re: Raw socket functionality
To: Geir Inge Jensen <>
From: Jeremy Cooper <>
List: current-users
Date: 03/13/1998 13:44:22
On Fri, 13 Mar 1998, Geir Inge Jensen wrote:

> How is IPPROTO_RAW supposed to work? I thought that I could send raw ip
> packets unchanged to the network. [ ... ]
> However, the packet that finally reaches the network has IPPROTO_RAW in
> its IP-header! Can I change this functionality?

IPPROTO_RAW notifies the IP protocol stack that to send IP packets with a
protocol field of ``RAW'' (as opposed to TCP, UDP, or ICMP), instead of
``RAW IP Packets'' as you are assuming.  Note this distinction carefully.

If you truly want to manufacture your own IP packets with headers
included, you must make a call to setsockopt() to toggle the IP_HDRINCL
flag on the socket before you use it.

  int state = 1;
  setsockopt(sockfd, 0, IP_HDRINCL, &state, sizeof(state))