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NG_MPPC(4)	       FreeBSD Kernel Interfaces Manual		    NG_MPPC(4)

NAME
     ng_mppc --	Microsoft MPPC/MPPE compression	and encryption netgraph	node
     type

SYNOPSIS
     #include <sys/types.h>
     #include <netgraph/ng_mppc.h>

DESCRIPTION
     The mppc node type	implements the Microsoft Point-to-Point	Compression
     (MPPC) and	Microsoft Point-to-Point Encryption (MPPE) sub-protocols of
     the PPP protocol.	These protocols	are often used in conjunction with the
     Point-to-Point Tunneling Protocol (PPTP).

     The node has two hooks, comp for compression and decomp for decompres-
     sion.  Typically one or both of these hooks would be connected to the
     ng_ppp(4) node type hook of the same name.	 Each direction	of traffic
     flow is independent of the	other.

HOOKS
     This node type supports the following hooks:

     comp	   Connection to ng_ppp(4) comp	hook.  Incoming	frames are
		   compressed and/or encrypted,	and sent back out the same
		   hook.
     decomp	   Connection to ng_ppp(4) decomp hook.	 Incoming frames are
		   decompressed	and/or decrypted, and sent back	out the	same
		   hook.

CONTROL	MESSAGES
     This node type supports the generic control messages, plus	the following:

     NGM_MPPC_CONFIG_COMP
	  This command resets and configures the node for a session in the
	  outgoing traffic direction (i.e., for	compression and/or encryp-
	  tion).  This command takes a struct ng_mppc_config as	an argument:

	  /* Length of MPPE key	*/
	  #define MPPE_KEY_LEN	    16

	  /* MPPC/MPPE PPP negotiation bits */
	  #define MPPC_BIT	    0x00000001	    /* mppc compression	bits */
	  #define MPPE_40	    0x00000020	    /* use 40 bit key */
	  #define MPPE_56	    0x00000080	    /* use 56 bit key */
	  #define MPPE_128	    0x00000040	    /* use 128 bit key */
	  #define MPPE_BITS	    0x000000e0	    /* mppe encryption bits */
	  #define MPPE_STATELESS    0x01000000	    /* use stateless mode */
	  #define MPPC_VALID_BITS   0x010000e1	    /* possibly	valid bits */

	  /* Configuration for a session */
	  struct ng_mppc_config	{
	      u_char	enable;			/* enable */
	      u_int32_t	bits;			/* config bits */
	      u_char	startkey[MPPE_KEY_LEN];	/* start key */
	  };

	  The enabled field enables traffic flow through the node.  The	bits
	  field	contains the bits as negotiated	by the Compression Control
	  Protocol (CCP) in PPP.  The startkey is only necessary if MPPE was
	  negotiated, and must be equal	to the session start key as defined
	  for MPPE.  This key is based on the MS-CHAP credentials used at link
	  authentication time.

     NGM_MPPC_CONFIG_DECOMP
	  This command resets and configures the node for a session in the
	  incoming traffic direction (i.e., for	decompression and/or decryp-
	  tion).  This command takes a struct ng_mppc_config as	an argument.

     NGM_MPPC_RESETREQ
	  This message contains	no arguments, and is bi-directional.  If an
	  error	is detected during decompression, this message is sent by the
	  node to the originator of the	NGM_MPPC_CONFIG_DECOMP message that
	  initiated the	session.  The receiver should respond by sending a PPP
	  CCP Reset-Request to the peer.

	  This message may also	be received by this node type when a CCP
	  Reset-Request	is received by the local PPP entity.  The node will
	  respond by flushing its outgoing compression and encryption state so
	  the remote side can resynchronize.

SHUTDOWN
     This node shuts down upon receipt of a NGM_SHUTDOWN control message, or
     when both hooks have been disconnected.

COMPILATION
     The kernel	options	NETGRAPH_MPPC_COMPRESSION and NETGRAPH_MPPC_ENCRYPTION
     are supplied to selectively compile in either or both capabilities.  At
     least one of these	must be	defined, or else this node type	is useless.

     The MPPC protocol requires	proprietary compression	code available from
     Hi/Fn (formerly STAC).  These files must be obtained elsewhere and	added
     to	the kernel sources before this node type will compile with the
     NETGRAPH_MPPC_COMPRESSION option.

SEE ALSO
     netgraph(4), ng_ppp(4), ngctl(8)

     G.	Pall, Microsoft	Point-To-Point Compression (MPPC) Protocol, RFC	2118.

     G.	S. Pall	and G. Zorn, Microsoft Point-To-Point Encryption (MPPE)
     Protocol, draft-ietf-pppext-mppe-04.txt.

     K.	Hamzeh,	G. Pall, W. Verthein, J. Taarud, W. Little, and	G. Zorn,
     Point-to-Point Tunneling Protocol (PPTP), RFC 2637.

AUTHORS
     Archie Cobbs <archie@FreeBSD.org>

BUGS
     In	PPP, encryption	should be handled by the Encryption Control Protocol
     (ECP) rather than CCP.  However, Microsoft	combined both compression and
     encryption	into their ``compression'' algorithm, which is confusing.

FreeBSD	10.1		       December	8, 1999			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | HOOKS | CONTROL MESSAGES | SHUTDOWN | COMPILATION | SEE ALSO | AUTHORS | BUGS

Want to link to this manual page? Use this URL:
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