4.2BSD AF_INET/SOCK_RAW wizard help needed

Landon C. Noll chongo at nsc.UUCP
Fri Nov 9 02:53:40 AEST 1984


I wish to setup low level ethernet communication between our vax 780 and
a 'small' system via ethernet.  I have the following givens:

vax:	* our vax 780 runs 4.2BSD and has an Interlan controller
	* our vax 780 talks to other 4.2 systems on the same cable
	* AF_INET (Internet) protocol is preferred

small:	* does not have enough memory to run a 4.2 kernel at the moment
	  so raw processing of packets is needed
	* will later run 4.2 with networking while still performing this
	  low level communication
	* no fancy reliability it needed for the communication, that is
	  the ethernet need only be a high speed 'rs232' style line
	  
My guess is that I will need to use a Raw socket prorocol.  (is this true???)
To do this, I need to at least understand the following:

	* How to send and receive via raw sockets on the 4.2 system
	* The byte-by-byte format of the resulting packets so the small
	  system and simply extract data, and format output packets

With the above in mind, here are my questions/requests:

	* Is Raw socket protocol what I need to use?
	* Would someone provide a example set of programs in C which do:
		+ runs on 4.2 systems and uses RAW INET sockets
		+ 1) establish a connection between each other
		+ 2) one party sends over two messages that contain
		     strings of say less than 512 bytes
		+ 3) the other party receives the two strings, cats them
		     together and sends them back and exists
		+ 4) the first party receives the 'strcat' message and exists
	* Can one force each message of the above program to be sent
	  in separate ethernet packets?  if so, how?
	* The key question:  What is the format of the all the ethernet
	  packets which are send by the above sample program?  That is, what
	  is the byte by byte layout of the actual ethernet packets?
	* Any other ideas?

chongo <thank you for your help> /\**/\

-- 
    "Don't blame me, I voted for Mondale!"
				John Alton 85'



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