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NAME

ng_pppoe — RFC 2516 PPPoE protocol netgraph node type

SYNOPSIS

#include <sys/types.h>
#include <net/ethernet.h>
#include <netgraph.h>
#include <netgraph/ng_pppoe.h>

DESCRIPTION

The pppoe node type performs the PPPoE protocol. It is used in conjunction with the netgraph(4) extensions to the Ethernet framework to divert and inject Ethernet packets to and from a PPP agent (which is not specified).

The NGM_PPPOE_GET_STATUS control message can be used at any time to query the current status of the PPPoE module. The only statistics presently available are the total packet counts for input and output. This node does not yet support the NGM_TEXT_STATUS control message.

HOOKS

This node type supports the following hooks:

ethernet

The hook that should normally be connected to an ng_ether(4) node. Once connected, ng_pppoe will send a message down this hook to determine Ethernet address of the underlying node. Obtained address will be stored and then used for outgoing datagrams.

debug

Presently no use.

[unspecified]

Any other name is assumed to be a session hook that will be connected to a PPP client agent, or a PPP server agent.

CONTROL MESSAGES

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

NGM_PPPOE_GET_STATUS

This command returns status information in a struct ngpppoestat:

struct ngpppoestat {
u_int packets_in; /* packets in from Ethernet */
u_int packets_out; /* packets out towards Ethernet */
};

NGM_TEXT_STATUS

This generic message returns a human-readable version of the node status. (not yet)

NGM_PPPOE_CONNECT (pppoe_connect)

Tell a nominated newly created hook that its session should enter the state machine as a client. It must be newly created and a service name can be given as an argument. It is legal to specify a zero-length service name, this is common on some DSL setups. It is possible to request a connection to a specific access concentrator, and/or set a specific Host-Uniq tag, required by some Internet providers, using the "[AC-Name][Host-Uniq|]Service-Name" syntax. To set a binary Host-Uniq, it must be encoded as a hexadecimal lowercase string and prefixed with "0x", for example "0x6d792d746167" is equivalent to "my-tag". A session request packet will be broadcast on the Ethernet. This command uses the ngpppoe_init_data structure shown below. For example, this init data argument can be used to connect to "my-isp" service with "my-host" uniq tag, accepting only "remote-ac" as access concentrator:

"remote-ac\my-host|my-isp"

NGM_PPPOE_LISTEN (pppoe_listen)

Tell a nominated newly created hook that its session should enter the state machine as a server listener. The argument given is the name of the service to listen for. A zero-length service name will match all requests for service. A matching service request packet will be passed unmodified back to the process responsible for starting the service. It can then examine it and pass it on to the session that is started to answer the request. This command uses the ngpppoe_init_data structure shown below.

NGM_PPPOE_OFFER (pppoe_offer)

Tell a nominated newly created hook that its session should enter the state machine as a server. The argument given is the name of the service to offer. A zero-length service is legal. The State machine will progress to a state where it will await a request packet to be forwarded to it from the startup server, which in turn probably received it from a LISTEN mode hook (see above). This is so that information that is required for the session that is embedded in the original session request packet, is made available to the state machine that eventually answers the request. When the Session request packet is received, the session negotiation will proceed. This command uses the ngpppoe_init_data structure shown below.

The three commands above use a common data structure:

struct ngpppoe_init_data {
char hook[NG_HOOKSIZ]; /* hook to monitor on */
uint16_t data_len; /* length of the service name */
char data[0]; /* init data goes here */
};

NGM_PPPOE_SUCCESS (pppoe_success)

This command is sent to the node that started this session with one of the above messages, and reports a state change. This message reports successful Session negotiation. It uses the structure shown below, and reports back the hook name corresponding to the successful session.

NGM_PPPOE_FAIL (pppoe_fail)

This command is sent to the node that started this session with one of the above messages, and reports a state change. This message reports failed Session negotiation. It uses the structure shown below, and reports back the hook name corresponding to the failed session. The hook will probably have been removed immediately after sending this message.

NGM_PPPOE_CLOSE (pppoe_close)

This command is sent to the node that started this session with one of the above messages, and reports a state change. This message reports a request to close a session. It uses the structure shown below, and reports back the hook name corresponding to the closed session. The hook will probably have been removed immediately after sending this message. At present this message is not yet used and a NGM_PPPOE_FAIL message will be received at closure instead.

NGM_PPPOE_ACNAME

This command is sent to the node that started this session with one of the above messages, and reports the Access Concentrator Name.

The four commands above use a common data structure:

struct ngpppoe_sts {
char hook[NG_HOOKSIZ];
};

NGM_PPPOE_GETMODE (pppoe_getmode)

This command returns the current compatibility mode of the node as a string. ASCII form of this message is "pppoe_getmode". The following keywords can be returned:

"standard"

The node operates according to RFC 2516.

"3Com"

When ng_pppoe is a PPPoE client, it initiates a session encapsulating packets into incorrect 3Com ethertypes. This compatibility option does not affect server mode. In server mode ng_pppoe supports both modes simultaneously, depending on the ethertype, the client used when connecting.

"D-Link"

When ng_pppoe is a PPPoE server serving only specific Service-Name(s), it will respond to a PADI requests with empty Service-Name tag, returning all available Service-Name(s) on node. This option is necessary for compatibility with D-Link DI-614+ and DI-624+ SOHO routers as clients, when serving only specific Service-Name. This compatibility option does not affect client mode.

NGM_PPPOE_SETMODE (pppoe_setmode)

Configure node to the specified mode. The string argument is required. This command understands the same keywords that are returned by the NGM_PPPOE_GETMODE command. ASCII form of this message is "pppoe_setmode". For example, the following command will configure the node to initiate the next session in the proprietary 3Com mode:

ngctl msg fxp0:orphans pppoe_setmode ’"3Com"’

NGM_PPPOE_SETENADDR (setenaddr)

Set the node Ethernet address for outgoing datagrams. This message is important when a node has failed to obtain an Ethernet address from its peer on the ethernet hook, or when user wants to override this address with another one. ASCII form of this message is "setenaddr".

NGM_PPPOE_SETMAXP (setmaxp)

Set the node PPP-Max-Payload value as described in RFC 4638. This message applies only to a client configuration. ASCII form of this message is "setmaxp".

Data structure returned to client is:

struct ngpppoe_maxp {
char hook[NG_HOOKSIZ];
uint16_t data;
};

NGM_PPPOE_SEND_HURL (send_hurl)

Tell a nominated hook with an active session to send a PADM message with a HURL tag. The argument is the URL to be delivered to the client:

ngctl msg fxp0:orphans send_hurl ’{ hook="myHook" data="http://example.net/cpe"; }’

NGM_PPPOE_SEND_MOTM (send_motm)

Tell a nominated hook with an active session to send a PADM message with a MOTM tag. The argument is the message to be delivered to the client:

ngctl msg fxp0:orphans send_motm ’{ hook="myHook" data="Welcome aboard" }’

The two commands above use the same ngpppoe_init_data structure described above.

NGM_PPPOE_HURL

This command is sent to the node that started this session when a PADM message with a HURL tag is received, and contains a URL that the host can pass to a web browser for presentation to the user.

NGM_PPPOE_MOTM

This command is sent to the node that started this session when a PADM message with a MOTM tag is received, and contains a Message Of The Minute that the host can display to the user.

The two commands above use a common data structure:

struct ngpppoe_padm {
char msg[PPPOE_PADM_VALUE_SIZE];
};

SHUTDOWN

This node shuts down upon receipt of a NGM_SHUTDOWN control message, when all session have been disconnected or when the ethernet hook is disconnected.

EXAMPLES

The following code uses libnetgraph to set up a ng_pppoe node and connect it to both a socket node and an Ethernet node. It can handle the case of when a ng_pppoe node is already attached to the Ethernet. It then starts a client session.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <sysexits.h>
#include <errno.h>
#include <err.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <net/ethernet.h>

#include <netgraph.h>
#include <netgraph/ng_ether.h>
#include <netgraph/ng_pppoe.h>
#include <netgraph/ng_socket.h>
static int setup(char *ethername, char *service, char *sessname,

int
main()
{

}

static int
setup(char *ethername, char *service, char *sessname,

{

#endif

}

SEE ALSO

netgraph(3), netgraph(4), ng_ether(4), ng_ppp(4), ng_socket(4), ngctl(8), ppp(8)

L. Mamakos

,

K. Lidl ,
J. Evarts ,
D. Carrel ,
D. Simone , and
R. Wheeler ,
A Method for transmitting PPP over Ethernet (PPPoE) ,
RFC 2516 .

HISTORY

The ng_pppoe node type was implemented in FreeBSD 4.0.

AUTHORS

Julian Elischer <julian [AT] FreeBSD.org>

BSD February 14, 2018 BSD