ifconfig

Linux Command – ifconfig ใช้ในการแสดงข้อมูลและเปลี่ยนค่า interface server

คำสั่ง

1. แสดงข้อมูล interface ทั้งหมด

ifconfig -a

$ ifconfig -a
enp2s0 Link encap:Ethernet HWaddr 00:1e:c9:54:6b:29 
 inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0
 inet6 addr: fe80::21e:c9ff:fe54:6b29/64 Scope:Link
 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
 RX packets:2244525 errors:0 dropped:2550 overruns:0 frame:0
 TX packets:2996535 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 txqueuelen:1000 
 RX bytes:355746122 (355.7 MB) TX bytes:869249389 (869.2 MB)
 Interrupt:16 

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:65536 Metric:1
 RX packets:571968 errors:0 dropped:0 overruns:0 frame:0
 TX packets:571968 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 txqueuelen:1 
 RX bytes:71550491 (71.5 MB) TX bytes:71550491 (71.5 MB)

2. แสดงข้อมูล interface ที่ระบุ

ifconfig <interface>

$ ifconfig enp2s0
enp2s0 Link encap:Ethernet HWaddr 00:1e:c9:54:6b:29 
 inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0
 inet6 addr: fe80::21e:c9ff:fe54:6b29/64 Scope:Link
 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
 RX packets:2245287 errors:0 dropped:2550 overruns:0 frame:0
 TX packets:2997483 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 txqueuelen:1000 
 RX bytes:355899284 (355.8 MB) TX bytes:869430494 (869.4 MB)
 Interrupt:16 

3. เปิดการใช้งาน interface ที่ระบุ

$ ifconfig <interface> up

4. ปิดการใช้งาน interface ที่ระบุ

$ ifconfig <interface> down

5. กำหนดค่า configure ของ interface

$ ifconfig <interface ><xxx.xxx.xxx.xxx> netmask <xxx.xxx.xxx.xxx> broadcast <xxx.xxx.xxx.xxx>.

$ ifconfig eth0 192.168.1.102 netmask 255.255.255.0 broadcast 192.168.1.255

โครงสร้างคำสั่ง

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

รายละเอียด

เป็นคำสั่งที่ใช้ในการแสดงข้อมูลและเปลี่ยนค่า interface server

Option

 -a display all interfaces which are currently available, even if down

 -s display a short list (like netstat -i)

 -v be more verbose for some error conditions

 interface
 The name of the interface. This is usually a driver name followed by a unit number, for example eth0 for the first Ethernet interface. If your kernel supports alias inter‐
 faces, you can specify them with eth0:0 for the first alias of eth0. You can use them to assign a second address. To delete an alias interface use ifconfig eth0:0 down.
 Note: for every scope (i.e. same net with address/netmask combination) all aliases are deleted, if you delete the first (primary).

 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 Enable or disable the use of the ARP protocol on this interface.

 [-]promisc
 Enable or disable the promiscuous mode of the interface. If selected, all packets on the network will be received by the interface.

 [-]allmulti
 Enable or disable all-multicast mode. If selected, all multicast packets on the network will be received by the interface.

 metric N
 This parameter sets the interface metric.

 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 obsolete; 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. Otherwise, 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
 The IP address to be assigned to this interface.

 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

กลุ่มคำสั่ง

ping, traceroute, route(8), netstat(8), arp(8), rarp(8), ipchains(8), iptables(8), ifup(8), interfaces(5).

Reference:

คำสั่ง Unix – Linux Command

Linux, Unix

Author: Suphakit Annoppornchai

Credit: https://saixiii.com