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.\" Author: Archie Cobbs <archie@FreeBSD.org>
.\"
.\" $FreeBSD: src/share/man/man4/ng_iface.4,v 1.13.2.1 2001/12/21 09:00:51 ru Exp $
.\" $Whistle: ng_iface.8,v 1.5 1999/01/25 23:46:26 archie Exp $
.\"
.Dd January 19, 1999
.Dt NG_IFACE 4
.Os
.Sh NAME
.Nm ng_iface
.Nd interface netgraph node type
.Sh SYNOPSIS
.In netgraph/iface/ng_iface.h
.Sh DESCRIPTION
An
.Nm iface
node is both a netgraph node and a system networking interface.  When an
.Nm iface
node is created, a new interface appears which is accessible via
.Xr ifconfig 8 .
.Nm Iface
node interfaces are named
.Dv ng0 ,
.Dv ng1 ,
etc.
When a node is shutdown, the corresponding interface is removed
and the interface name becomes available for reuse by future
.Nm iface
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.
.Pp
An
.Nm iface
node has a single hook corresponding to each supported protocol.
Packets transmitted via the interface flow out the corresponding
protocol-specific hook.
Similarly, packets received on a hook appear on the interface as
packets received into the corresponding protocol stack.
The currently supported protocols are IP, IPv6, AppleTalk, ATM,
NATM, and NS.
.Pp
An
.Nm iface
node be configured as a point-to-point interface or a broadcast interface.
The configuration can only be changed when the interface is down.
The default mode is point-to-point.
.Pp
.Nm Iface
nodes support the Berkeley Packet Filter (BPF).
.Sh HOOKS
This node type supports the following hooks:
.Bl -tag -width foobar
.It Dv inet
Transmission and reception of IP packets.
.It Dv inet6
Transmission and reception of IPv6 packets.
.It Dv atalk
Transmission and reception of AppleTalk packets.
.It Dv atm
Transmission and reception of ATM packets.
.It Dv natm
Transmission and reception of NATM packets.
.It Dv ns
Transmission and reception of NS packets.
.El
.Sh CONTROL MESSAGES
This node type supports the generic control messages, plus the following:
.Bl -tag -width foo
.It Dv NGM_IFACE_GET_IFNAME
Returns the name of the interface corresponding to this node in a
.Dv "struct ng_iface_ifname" :
.Bd -literal -offset 4n
struct ng_iface_ifname {
  char  ngif_name[NG_IFACE_IFACE_NAME_MAX + 1];
};
.Ed
.It Dv NGM_IFACE_POINT2POINT
Set the interface to point-to-point mode.
The interface must not currently be up.
.It Dv NGM_IFACE_BROADCAST
Set the interface to broadcast mode.
The interface must not currently be up.
.It Dv NGM_CISCO_GET_IPADDR
This message is defined by the
.Xr ng_cisco 4
node type; see
.Xr ng_cisco 4
for a description.
.El
.Sh SHUTDOWN
This node shuts down upon receipt of a
.Dv NGM_SHUTDOWN
control message.  The associated interface is removed and becomes available
for use by future
.Nm iface
nodes.
.Pp
Unlike most other node types, an
.Nm iface
node does
.Em not
go away when all hooks have been disconnected; rather, and explicit
.Dv NGM_SHUTDOWN
control message is required.
.Sh SEE ALSO
.Xr bpf 4 ,
.Xr netgraph 4 ,
.Xr ng_cisco 4 ,
.Xr ifconfig 8 ,
.Xr ngctl 8
.Sh HISTORY
The
.Nm iface
node type was implemented in
.Fx 4.0 .
.Sh AUTHORS
.An Archie Cobbs Aq Mt archie@FreeBSD.org