命令格式：

  ifconfig [-v] [-a] [-s] [interface]

  ifconfig [-v] interface [aftype] options | address ...

配置网络接口

选项：

  -a     显示当前所有可获取的网络接口信息，包括状态为down的接口

  -s     已短列表方式显示（类似 netstat -i)

  -v     be more verbose for some error conditions

  interface

    网络接口名称

  up     This flag causes the interface to be activated.  It is implicitly specified if  an  address  is

    assigned to the interface.

  down   This flag causes the driver for this interface to be shut down.

  [-]arp 打开或关闭指定接口上的ARP协议。前面加上减号用于关闭该选项。

  [-]promisc

    关闭或启动指定网络设备的混杂模式（promiscuous mode）。如果启动混杂模式，该网络接口将接收网络上的所有数据包。

    前面加上减号用于关闭该选项。

  [-]allmulti

    Enable or disable all-multicast mode.  If selected, all multicast packets on the  network  will

    be received by the interface.

  mtu N  This parameter sets the Maximum Transfer Unit (MTU) of an interface.

  dstaddr addr

    Set  the  remote IP address for a point-to-point link (such as PPP).  This keyword is now obso‐

    lete; use the pointopoint keyword instead.

  netmask addr

    Set the IP network mask for this interface.  This value defaults to the usual class A, B  or  C

    network mask (as derived from the interface IP address), but it can be set to any value.

  add addr/prefixlen

    Add an IPv6 address to an interface.

  del addr/prefixlen

    Remove an IPv6 address from an interface.

  tunnel ::aa.bb.cc.dd

    Create a new SIT (IPv6-in-IPv4) device, tunnelling to the given destination.

  irq addr

    Set  the  interrupt line used by this device.  Not all devices can dynamically change their IRQ

    setting.

  io_addr addr

    Set the start address in I/O space for this device.

  mem_start addr

    Set the start address for shared memory used by this device.  Only a few devices need this.

  media type

    Set the physical port or medium type to be used by the device.  Not all devices can change this

    setting,  and  those  that  can  vary in what values they support.  Typical values for type are

    10base2 (thin Ethernet), 10baseT (twisted-pair 10Mbps Ethernet), AUI (external transceiver) and

    so on.  The special medium type of auto can be used to tell the driver to auto-sense the media.

    Again, not all drivers can do this.

  [-]broadcast [addr]

    If the address argument is given, set the protocol broadcast address for this interface.   Oth‐

    erwise, set (or clear) the IFF_BROADCAST flag for the interface.

  [-]pointopoint [addr]

    This  keyword enables the point-to-point mode of an interface, meaning that it is a direct link

    between two machines with nobody else listening on it.

    If the address argument is also given, set the protocol address of the other side of the  link,

    just  like the obsolete dstaddr keyword does.  Otherwise, set or clear the IFF_POINTOPOINT flag

    for the interface.

  hw class address

    Set the hardware address of this interface, if the device driver supports this operation.   The

    keyword  must  be followed by the name of the hardware class and the printable ASCII equivalent

    of the hardware address.  Hardware classes currently supported include ether  (Ethernet),  ax25

    (AMPR AX.25), ARCnet and netrom (AMPR NET/ROM).

  multicast

    Set  the multicast flag on the interface. This should not normally be needed as the drivers set

    the flag correctly themselves.

  address

    给接口指定的IP地址.

  txqueuelen length

    Set the length of the transmit queue of the device. It is useful to set this  to  small  values

    for  slower devices with a high latency (modem links, ISDN) to prevent fast bulk transfers from

    disturbing interactive traffic like telnet too much.

应用举例：

# ifconfig