Manual Pages  — NG_SPPP

#include <netgraph/ng_sppp.h>

An sppp node is a netgraph(4) interface to the original sppp(4) network module for synchronous lines. Currently, sppp(4) supports PPP and Cisco HDLC protocols. An sppp node could be considered as an alternative kernel mode PPP implementation to net/mpd port + ng_ppp(4), and as an alternative to ng_cisco(4) node. While having less features than net/mpd + ng_ppp(4), it is significantly easier to use in the majority of simple configurations, and allows the administrator to not install the net/mpd port. With sppp you do not need any other nodes, not even an ng_iface(4) node. When an sppp node is created, a new interface appears which is accessible via ifconfig(8). Network interfaces corresponding to sppp nodes are named sppp0, sppp1, etc. When a node is shut down, the corresponding interface is removed, and the interface name becomes available for reuse by future sppp nodes. New nodes always take the first unused interface. The node itself is assigned the same name as its interface, unless the name already exists, in which case the node remains unnamed. The sppp node allows drivers written to the old sppp(4) interface to be rewritten using the newer more powerful netgraph(4) interface, and still behave in a compatible manner without supporting both network modules.

An sppp node has a single hook named downstream. Usually it is connected directly to a device driver hook.

The sppp nodes support the Berkeley Packet Filter, bpf(4).

For example, if you have the cx(4) device, you could run PPP over it with just one command:

    ngctl mkpeer cx0: sppp rawdata downstream

Now you have the sppp0 interface (if this was the first sppp node) which can be accessed via ifconfig(8) as a normal network interface, or via spppcontrol(8) as an sppp(4) interface.

bpf(4), cx(4), netgraph(4), ng_cisco(4), ng_iface(4), ng_ppp(4), sppp(4), ifconfig(8), ngctl(8), spppcontrol(8)

For complex networking topologies you may want to look at net/mpd port.