ifconfig
ifconfig
ifconfig
is a command-line utility used to configure network interfaces on Unix-like operating systems, including Linux. It is part of the net-tools package and is used to view and manage network interface configurations.
View All Network Interfaces:
ifconfig
This command displays information about all active network interfaces on the system.
View a Specific Network Interface:
ifconfig eth0
Replace
eth0
with the name of the network interface you want to view. This command displays detailed information about the specified interface.Bring Up a Network Interface:
ifconfig eth0 up
This command activates the
eth0
network interface.Bring Down a Network Interface:
ifconfig eth0 down
This command deactivates the
eth0
network interface.Assign an IP Address to a Network Interface:
ifconfig eth0 192.168.1.10 netmask 255.255.255.0
This command assigns the IP address
192.168.1.10
with a subnet mask of255.255.255.0
to theeth0
interface.Change the MTU of a Network Interface:
ifconfig eth0 mtu 1500
This command sets the Maximum Transmission Unit (MTU) of the
eth0
interface to1500
bytes.Assign an IP Address with Broadcast and Netmask:
ifconfig eth0 192.168.1.10 netmask 255.255.255.0 broadcast 192.168.1.255
This command assigns the IP address
192.168.1.10
, subnet mask255.255.255.0
, and broadcast address192.168.1.255
to theeth0
interface.Assign a MAC Address to a Network Interface:
ifconfig eth0 hw ether 00:1A:2B:3C:4D:5E
This command assigns the MAC address
00:1A:2B:3C:4D:5E
to theeth0
interface.
Example of ifconfig
Output
ifconfig
OutputWhen you run ifconfig
without any arguments, you might see output similar to this:
eth0 Link encap:Ethernet HWaddr 00:0c:29:36:bc:91
inet addr:192.168.1.10 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fe36:bc91/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:12345 errors:0 dropped:0 overruns:0 frame:0
TX packets:67890 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1048576 (1.0 MB) TX bytes:524288 (512.0 KB)
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:10 errors:0 dropped:0 overruns:0 frame:0
TX packets:10 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:820 (820.0 B) TX bytes:820 (820.0 B)
Deprecation Notice
While ifconfig
is still widely used, it is considered deprecated in favor of the ip
command from the iproute2
package. The ip
command provides more functionality and better capabilities for modern network configuration.
Basic Usage of ip
Command
ip
CommandView All Network Interfaces:
ip addr
View a Specific Network Interface:
ip addr show dev eth0
Bring Up a Network Interface:
ip link set eth0 up
Bring Down a Network Interface:
ip link set eth0 down
Assign an IP Address to a Network Interface:
ip addr add 192.168.1.10/24 dev eth0
Change the MTU of a Network Interface:
ip link set dev eth0 mtu 1500
Conclusion
ifconfig
is a powerful and widely used tool for network configuration on Unix-like systems. Despite being deprecated in favor of the ip
command, it remains an important utility, especially in legacy systems and for quick network interface management tasks. For modern and more complex networking tasks, transitioning to the ip
command is recommended.
help
Usage:
ifconfig [-a] [-v] [-s] <interface> [[<AF>] <address>]
[add <address>[/<prefixlen>]]
[del <address>[/<prefixlen>]]
[[-]broadcast [<address>]] [[-]pointopoint [<address>]]
[netmask <address>] [dstaddr <address>] [tunnel <address>]
[outfill <NN>] [keepalive <NN>]
[hw <HW> <address>] [mtu <NN>]
[[-]trailers] [[-]arp] [[-]allmulti]
[multicast] [[-]promisc]
[mem_start <NN>] [io_addr <NN>] [irq <NN>] [media <type>]
[txqueuelen <NN>]
[[-]dynamic]
[up|down] ...
breakdown
-a, --all: This option displays all network interfaces.
-s, --statistics: This option displays statistics for the specified interface.
-v, --verbose: This option displays more information.
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