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NAMEng_iface - interface netgraph node type
DESCRIPTIONAn 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, 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).
HOOKSThis node type supports the following hooks:
- Transmission and reception of IP packets.
- Transmission and reception of IPv6 packets.
- Transmission and reception of ATM packets.
- Transmission and reception of NATM packets.
- Transmission and reception of NS packets.
CONTROL MESSAGESThis node type supports the generic control messages, plus the following:
- NGM_IFACE_GET_IFNAME (getifname )
- 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 (getifindex )
- Returns the global index of the associated interface as a 32 bit integer.
- NGM_IFACE_POINT2POINT (point2point )
- Set the interface to point-to-point mode. The interface must not currently be up.
- NGM_IFACE_BROADCAST (broadcast )
- Set the interface to broadcast mode. The interface must not currently be up.
SHUTDOWNThis 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.