Re: raw sockets: question about sending IP + UDP header

From: Barry Margolin (barmar_at_alum.mit.edu)
Date: 10/22/05

  • Next message: Henry Townsend: "Re: wait(pid) problem" 
    Date: Sat, 22 Oct 2005 12:40:03 -0400

    In article <wst6f.10140$Io4.15@trnddc06>,
     Fernando Barsoba <fbarsoba@verizon.net> wrote:

    > Hi all,
    >
    > I'm working on a IPSec implementation (raw sockets), and the first stage
    > that I defined for this project involves the following (conceptually):
    >
    > - First, build an IP datagram and add a UDP header to it. Try to send
    > the UDP datagram through a raw socket client to a UDP socket server.
    > Check with Ethereal if communication between hosts is correct, i.e. the
    > datagram is correctly formed and correctly send/received. (here I want
    > to test if my IP header and IP checksum is correct plus of course my UDP
    > header is correct.. though I will get rid of it eventually and start
    > working on the IPSec header)
    >
    > Here's my question: I expect that my UDP datagram will be processed and
    > sent to my UDP socket server through the raw socket.. but, will the
    > kernel mess with my UDP packet on the client side? (the kernel doesn't
    > process anything that doesn't recognize in the protocol field, but in
    > this case it will recognize it as UDP packet)
    >
    > I hope my question is not too wordy..

    There's a chapter on Raw Sockets in Unix Network Programming, Vol.1. It
    explains which fields the stack will fill in by itself, and which it
    will leave alone. 

    -- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
  • Next message: Henry Townsend: "Re: wait(pid) problem"

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