freebsd-src/share/man/man4/ng_ether.4

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.\" Author: Archie Cobbs <archie@whistle.com>
.\"
.\" $FreeBSD$
.\"
.Dd June 26, 2000
.Dt NG_ETHER 4
.Os FreeBSD
.Sh NAME
.Nm ng_ether
.Nd Ethernet netgraph node type
.Sh SYNOPSIS
.Fd #include <netgraph/ng_ether.h>
.Sh DESCRIPTION
The
.Nm ng_ether
netgraph node type allows Ethernet interfaces to interact with
the
.Xr netgraph 4 
networking subsystem.
Once the
.Nm
module is loaded in the kernel, a node is automatically created
for each Ethernet interface in the system.
Each node will attempt to name itself with the same name
as the associated interface.
All
.Nm
nodes are persistent for as long as the interface itself exists.
.Pp
Three hooks are supported:
.Dv lower ,
.Dv upper ,
and
.Dv orphans .
The hook name
.Dv divert
may be used as an alias for
.Dv lower ,
and is provided for backward compatibility.
In reality the two names represent the same hook.
.Pp
The
.Dv lower
hook is a connection to the raw Ethernet device.
When connected, all incoming packets are diverted out this hook.
Writing to this hook results in a raw Ethernet frame being transmitted
by the device.
Normal outgoing packets are not affected by
.Dv lower
being connected.
.Pp
The
.Dv upper
hook is a connection to the upper protocol layers.
When connected, all outgoing packets are diverted out this hook.
Writing to this hook results in a raw Ethernet frame being received by
the kernel just as if it had come in over the wire.
Normal incoming packets are not affected by
.Dv upper
being connected.
.Pp
The
.Dv orphans
hook is equivalent to
.Dv lower ,
except that only unrecognized packets (that would otherwise be discarded)
are written to the hook, and normal incoming traffic is unaffected.
At most one of
.Dv orphans
and
.Dv lower
may be connected at any time.
.Pp
In all cases, frames are raw Ethernet frames with the standard
14 byte Ethernet header (but no checksum).
.Pp
When no hooks are connected,
.Dv upper
and
.Dv lower
are in effect connected together,
so that packets flow normally upwards and downwards.
.Sh HOOKS
This node type supports the following hooks:
.Pp
.Bl -tag -width orphans
.It Dv lower
Connection to the lower device link layer.
.It Dv upper
Connection to the upper protocol layers.
.It Dv orphans
Like
.Dv lower ,
but only receives unrecognized packets.
.El
.Sh CONTROL MESSAGES
This node type supports the generic control messages, plus the following:
.Bl -tag -width foo
.It Dv NGM_ETHER_GET_IFNAME
Returns the name of the associated interface as a NUL-terminated ASCII string.
Normally this is the same as the name of the node.
.It Dv NGM_ETHER_GET_IFINDEX
Returns the global index of the associated interface as a 32 bit integer.
.El
.Sh SHUTDOWN
This node is persistent for as long as the interface exists.
Upon receipt of a
.Dv NGM_SHUTDOWN
control message, all hooks are disconnected, but the node is not removed.
If the interface itself is detached (e.g., because of PCCARD removal), the
node disappears as well.
.Sh EXAMPLE
This command dumps all unrecognized packets received by the
.Dv fxp0
interface to standard output decoded in hex and ASCII:
.Bd -literal -offset indent
nghook -a fxp0: orphans
.Ed
.Pp
This command sends the contents of
.Dv foo.pkt
out the interface
.Dv ed0 :
.Bd -literal -offset indent
cat foo.pkt | nghook fxp0: orphans
.Ed
.Pp
These commands insert an
.Xr ng_tee 4
node between the lower and upper protocol layers, which can be used for
tracing packet flow, statistics, etc.:
.Bd -literal -offset indent
ngctl mkpeer fxp0: tee lower right
ngctl connect fxp0: lower upper left
.Ed
.Sh SEE ALSO
.Xr arp 4 ,
.Xr netgraph 4 ,
.Xr netintro 4 ,
.Xr ifconfig 8 ,
.Xr nghook 8 ,
.Xr ngctl 8
.Sh AUTHORS
.An Julian Elischer Aq julian@FreeBSD.org
.An Archie Cobbs Aq archie@FreeBSD.org