ifconfig utility for linux users
Ifconfig stands for "Interface Configuration" .It is a utility for Linux machines to configure,assign,add,delete,control and query network interface in Unix/Linux machine.
Common Linux users uses IFCONFIG command to assign ip address and netmask to an interface or to disable or enable a given interface.
Lets see how a Linux admin or a linux geek can have fun with this simple command.
slashroot is today will explain the power, the real strength of ifconfig command.
1.Show Network Devices and configuration and all network setting
[root@satish ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:1B:B9:B3:BD:4F
inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:201 Base address:0xc00
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:9439 errors:0 dropped:0 overruns:0 frame:0
TX packets:9439 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:5524963 (5.2 MiB) TX bytes:5524963 (5.2 MiB)
ppp0 Link encap:Point-to-Point Protocol
inet addr:106.219.181.163 P-t-P:10.64.64.64 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:8444 errors:0 dropped:0 overruns:0 frame:0
TX packets:8991 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:7785191 (7.4 MiB) TX bytes:1164790 (1.1 MiB)
Explanation:Here clearly you can see the output of ifconfig command. It has displayed the information of network intefaces.
eth0: is my ethernet card
lo: is loopback address
ppp0:Point-to-point Protocol.
2.How to Display the Information of all network interface
#ifconfig -a
[root@satish ~]# ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:1B:B9:B3:BD:4F
inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:201 Base address:0xc00
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:10033 errors:0 dropped:0 overruns:0 frame:0
TX packets:10033 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:5555990 (5.2 MiB) TX bytes:5555990 (5.2 MiB)
ppp0 Link encap:Point-to-Point Protocol
inet addr:106.219.181.163 P-t-P:10.64.64.64 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:8468 errors:0 dropped:0 overruns:0 frame:0
TX packets:9090 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:7787427 (7.4 MiB) TX bytes:1170752 (1.1 MiB)
sit0 Link encap:IPv6-in-IPv4
NOARP MTU:1480 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Note:Now a days ip command is getting more marks in Linux world, when you go through the man page of ip command you will find that it is more easy and it also have the capacity to do the same and thats little bit tricky too.
Lets see How one can see network Devices and Configuration through ip command in Linux.
[root@satish ~]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:1b:b9:b3:bd:4f brd ff:ff:ff:ff:ff:ff
inet 192.168.1.1/24 brd 192.168.1.255 scope global eth0
3: sit0: <NOARP> mtu 1480 qdisc noop
link/sit 0.0.0.0 brd 0.0.0.0
4: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 3
link/ppp
inet 106.219.181.163 peer 10.64.64.64/32 scope global ppp0
We have one more command with Ip to show more about network configuration and Devices
[root@satish ~]# ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:1b:b9:b3:bd:4f brd ff:ff:ff:ff:ff:ff
3: sit0: <NOARP> mtu 1480 qdisc noop
link/sit 0.0.0.0 brd 0.0.0.0
4: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 3
link/ppp
3.View the Network configuration of a Specific Interface
[root@satish ~]# ifconfig ppp0
ppp0 Link encap:Point-to-Point Protocol
inet addr:106.219.181.163 P-t-P:10.64.64.64 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:8980 errors:0 dropped:0 overruns:0 frame:0
TX packets:9758 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:8289652 (7.9 MiB) TX bytes:1240309 (1.1 MiB)
4.How to Enabale a Network Interface
#ifup eth0#ifconfig eth0 up
5.How to Disable a Network Interface
#ifconfig eth0 downOR
#ifdown eth0
6.How to assign ip to a Network Interface
#ifconfig eth0 192.168.1.1#ip address add 192.168.1.1 dev eth0
7.How to assign Netmask to a network interface
#ifconfig eth0 netmask 255.255.255.0
8.How to Delete a ip address
#ip addr del 192.168.1.1/24 dev eth0
9.How to assign everything(ip address,netmask and network up) in a single command line.
#ifconfig eth0 netmask 255.255.255.0 up
10.How to assign a Broadcast address to a network interface
#ifconfig eth0 broadcast 192.168.1.255
Note:Broadcaste address is a 32 bit address pattern in which all host bits are "1"
11.How to assign all ip address,netmask and broadcast address at a time
#ifconfig etho 192.168.1.1 netmask 255.255.255.0 broadcast 192.168.1.255
12.How to change the Mac Address of a Network Interface card
#ifconfig eth0 hw ether FF:GG:HH:II:JJ:KK
13.How to add a new alias to a network interface
#ifconfig eth0:0 192.168.1.100
14.How To View or Verify whether New alias set or not on network interface
[root@satish ~]# ifconfig eth0:0
eth0:0 Link encap:Ethernet HWaddr 00:1B:B9:B3:BD:4F
inet addr:192.168.1.100 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
Interrupt:201 Base address:0xc00
15.How to remove alias network
#ifconfig eth0:0 down
16.How to change MTU(Maximum Transmission Unit) for a network interface
#ifconfig mtu 1000
17.How to enable Promiscuous mode
#ifconfig eth0 promisc
18.How to Disable Promiscuous mode
#ifconfig eth0 -promisc
what is Promiscuous mode?
answer: Promiscous mode is used to accept all the packets that flows through the NIC(Network Interface Card)
Most of today hacking and network capturing tools used this mode to capture and analyze the packets that flow through the Network Interface card.
What happens in a Normal Mode?
In a Normal mode whenever a packet received by a NIC,it verify that whether the packet belongs to itself or not. If it's not, it drops the packet normaly, while it's not so in Promiscuous mode.
How to get your external IP Address?
[root@localhost ~]# curl ifconfig.me
106.223.44.33
[root@localhost ~]#
Dear Readers if you have any suggestion regarding this post slashroot welcome you to share your knowledge.
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