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From: sameer <sameer@c2.net>
Message-Id: <199710302048.MAA15533@gabber.c2.net>
Subject: Whee, PPP over TCP working
To: freebsd-hackers@freebsd.org
Date: Thu, 30 Oct 1997 12:48:33 -0800 (PST)
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	So I didn't see anything in the archives about how to get PPP
over TCP working, so I figured it out myself. =) 

	Here's how to do it.. hopefully someone can integrate this
into the docs, etc.

On the client, edit ppp.conf as follows:

ppptcp:
 set device remotehost:1324
 set dial ""
 set ifaddr 10.1.1.1 10.1.1.2

On the server, edit ppp.conf as follows:

tcpserver:
  set ifaddr 10.1.1.2 10.1.1.1


	If you want to use PAP/CHAP, whatever, then you should add
appropriate configuration for PAP/CHAP.

	On the server, you need to plug the ppp user-land program onto
a port. I wrote the following program to do that -- it has zero
error-checking, it probably leaks fd's left and right, and it could be
improved to do a login/password thing... there's a lot you can do to
improve it, but I didn't have the time, I just wanted to put together
a proof of concept.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

int main(void)
{
  int s = socket(PF_INET, SOCK_STREAM, 0);
  int a;
  struct sockaddr_in addr;

  addr.sin_addr.s_addr = htonl(INADDR_ANY);
  addr.sin_port = htons(1324);
  addr.sin_family = AF_INET;

  bind(s, (struct sockaddr *) &addr, sizeof(addr));

  listen(s, 15);

  while(1)
    {
      struct sockaddr_in remote;
      int size;
      a = accept(s, (struct sockaddr *) &remote, &size);
      /* Fork the subprocess to do proxying */

      if(!fork()) {
	char *message = "PPP/TCP Server Connected\n";

	/* Spit out some stuff to the client to know we're connected */
	write(a, message, strlen(message));
	
	/* Dup some fd's and run ppp -direct */

	dup2(a, STDOUT_FILENO);
	dup2(a, STDIN_FILENO);
	close(a);

	execl("/usr/sbin/ppp", "ppp", "-direct", "tcpserver", NULL);
      }
    }
}

So then on the server, you just run

> ./ppp-tcp


Then on the client you can run

> ppp ppptcp
User Process PPP. Written by Toshiharu OHNO.
Log level is 09
can't open /etc/ppp/ppp.secret.
Warning: No password entry for this host in ppp.secret
Warning: All manipulation is allowed by anyone in the world
Using interface: tun0
Interactive mode
ppp ON gabber> dial
Dial attempt 1
dial OK!
login OK!
ppp ON gabber> Packet mode.
ppp ON gabber> 
PPP ON gabber>


On the server you'll end up seeing:

{0} lachesis:sameer/ppp-tcp 12:46pm [14] > ./ppp-tcp
Log level is 281
can't open /etc/ppp/ppp.secret.
Warning: No password entry for this host in ppp.secret
Warning: All manipulation is allowed by anyone in the world

	then you'll be all set. You can ping, etc.


  
  

 
-- 
Sameer Parekh					Voice:   510-986-8770
President					FAX:     510-986-8777
C2Net
http://www.c2.net/				sameer@c2.net