Linux ifconfig Command

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The Linux ifconfig command is used to display or configure network devices.

ifconfig can set the status of network devices, or display the current settings.

Syntax

ifconfig [网络设备][down up -allmulti -arp -promisc][add<地址>][del<地址>][<hw<网络设备类型><硬件地址>][io_addr<I/O地址>][irq<IRQ地址>][media<网络媒介类型>][mem_start<内存地址>][metric<数目>][mtu<字节>][netmask<子网掩码>][tunnel<地址>][-broadcast<地址>][-pointopoint<地址>][IP地址]

Parameter Description：

  • add<address> Set the IPv6 IP address of the network device.
  • del<address> Delete the IPv6 IP address of the network device.
  • down Shut down the specified network device.
  • <hw<network device type><hardware address> Set the type and hardware address of the network device.
  • io_addr<I/O address> Set the I/O address of the network device.
  • irq<IRQ address> Set the IRQ of the network device.
  • media<network media type> Set the media type of the network device.
  • mem_start<memory address> Set the starting address occupied by the network device in main memory.
  • metric<number> Specify the number to be added when calculating the forwarding count of data packets.
  • mtu<bytes> Set the MTU of the network device.
  • netmask<subnet mask> Set the subnet mask of the network device.
  • tunnel<address> Establish a tunnel communication address between IPv4 and IPv6.
  • up Start the specified network device.
  • -broadcast<address> Treat data packets destined for the specified address as broadcast packets.
  • -pointopoint<address> Establish a direct connection with the network device at the specified address; this mode has confidentiality features.
  • -promisc Disable or enable the promiscuous mode of the specified network device.
  • [IP address] Specify the IP address of the network device.
  • [network device] Specify the name of the network device.

Examples

Display network device information

# ifconfig        
eth0   Link encap:Ethernet HWaddr 00:50:56:0A:0B:0C 
     inet addr:192.168.0.3 Bcast:192.168.0.255 Mask:255.255.255.0
     inet6 addr: fe80::250:56ff:fe0a:b0c/64 Scope:Link
     UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
     RX packets:172220 errors:0 dropped:0 overruns:0 frame:0
     TX packets:132379 errors:0 dropped:0 overruns:0 carrier:0
     collisions:0 txqueuelen:1000 
     RX bytes:87101880 (83.0 MiB) TX bytes:41576123 (39.6 MiB)
     Interrupt:185 Base address:0x2024 

lo    Link encap:Local Loopback 
     inet addr:127.0.0.1 Mask:255.0.0.0
     inet6 addr: ::1/128 Scope:Host
     UP LOOPBACK RUNNING MTU:16436 Metric:1
     RX packets:2022 errors:0 dropped:0 overruns:0 frame:0
     TX packets:2022 errors:0 dropped:0 overruns:0 carrier:0
     collisions:0 txqueuelen:0 
     RX bytes:2459063 (2.3 MiB) TX bytes:2459063 (2.3 MiB)

Start or shut down the specified network card

# ifconfig eth0 down
# ifconfig eth0 up

Configure and delete IPv6 addresses for the network card

# ifconfig eth0 add 33ffe:3240:800:1005::2/ 64 //为网卡设置IPv6地址

# ifconfig eth0 del 33ffe:3240:800:1005::2/ 64 //为网卡删除IPv6地址

Use ifconfig to modify the MAC address

# ifconfig eth0 down //关闭网卡
# ifconfig eth0 hw ether 00:AA:BB:CC:DD:EE //修改MAC地址
# ifconfig eth0 up //启动网卡
# ifconfig eth1 hw ether 00:1D:1C:1D:1E //关闭网卡并修改MAC地址 
# ifconfig eth1 up //启动网卡

Configure IP address

# ifconfig eth0 192.168.1.56 
//给eth0网卡配置IP地址
# ifconfig eth0 192.168.1.56 netmask 255.255.255.0 
// 给eth0网卡配置IP地址,并加上子掩码
# ifconfig eth0 192.168.1.56 netmask 255.255.255.0 broadcast 192.168.1.255
// 给eth0网卡配置IP地址,加上子掩码,加上个广播地址

Enable and disable the ARP protocol

# ifconfig eth0 arp  //开启
# ifconfig eth0 -arp  //关闭

Set the maximum transmission unit

# ifconfig eth0 mtu 1500 
//设置能通过的最大数据包大小为 1500 bytes

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