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NAME

     ng_iface - interface netgraph node type

SYNOPSIS

     #include <netgraph/ng_iface.h>

DESCRIPTION

     An iface node is both a netgraph node and a system networking interface.
     When an iface node is created, a new interface appears which is
     accessible via ifconfig(8).  Iface node interfaces are named ng0, ng1,
     etc.  When a node is shutdown, the corresponding interface is removed and
     the interface name becomes available for reuse by future 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.

     An 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, IPX, ATM,
     NATM, and NS.

     An iface node can 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.

     Iface nodes support the Berkeley Packet Filter (BPF).

HOOKS

     This node type supports the following hooks:

     inet    Transmission and reception of IP packets.

     inet6   Transmission and reception of IPv6 packets.

     atalk   Transmission and reception of AppleTalk packets.

     ipx     Transmission and reception of IPX packets.

     atm     Transmission and reception of ATM packets.

     natm    Transmission and reception of NATM packets.

     ns      Transmission and reception of NS packets.

CONTROL MESSAGES

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

     NGM_IFACE_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.

     NGM_IFACE_GET_IFINDEX
          Returns the global index of the associated interface as a 32 bit
          integer.

     NGM_IFACE_POINT2POINT
          Set the interface to point-to-point mode.  The interface must not
          currently be up.

     NGM_IFACE_BROADCAST
          Set the interface to broadcast mode.  The interface must not
          currently be up.

     NGM_CISCO_GET_IPADDR
          This message is defined by the ng_cisco(4) node type; see
          ng_cisco(4) for a description.

SHUTDOWN

     This node shuts down upon receipt of a NGM_SHUTDOWN control message.  The
     associated interface is removed and becomes available for use by future
     iface nodes.

     Unlike most other node types, an iface node does not go away when all
     hooks have been disconnected; rather, and explicit NGM_SHUTDOWN control
     message is required.

ALTQ Support

     The ng_iface interface supports ALTQ bandwidth management feature.
     However, ng_iface is a special case, since it is not a physical interface
     with limited bandwidth.  One should not turn ALTQ on ng_iface if the
     latter corresponds to some tunneled connection, e.g. PPPoE or PPTP.  In
     this case, ALTQ should be configured on the interface that is used to
     transmit the encapsulated packets.  In case when your graph ends up with
     some kind of serial line, either synchronous or modem, the ng_iface is
     the right place to turn ALTQ on.

SEE ALSO

     altq(4), bpf(4), netgraph(4), ng_cisco(4), ifconfig(8), ngctl(8)

HISTORY

     The iface node type was implemented in FreeBSD 4.0.

AUTHORS

     Archie Cobbs 〈archie@FreeBSD.org