Wifi Connectivity, eth0 and wlan0 interface?

Question

I do not have any problem in Internet connectivity, both in terminal and in browser.

Few days earlier, I used to get a dynamic ipv4 address to eth0 from my ISP and the interface used to be up and running. I do not know with what of my changes, the ip has migrated to wlan0 ?

1. Can you please explain, what exactly has happened ? It might help me further to understand the virtual NICs funda !

2. Can I consider the ip assigned to my PC is wlan0 ip ? (layer 3 ip to connect to external world )

Thanks.

Ubuntu 14.04 !
ifconfig eth0 
eth0      Link encap:Ethernet  HWaddr 00:1f:16:6c:b0:1f  
          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)

sriduth@sriduth-HP-G60-Notebook-PC:~$ ifconfig wlan0
wlan0     Link encap:Ethernet  HWaddr 00:24:2c:3b:f8:79  
          inet addr:192.168.1.102  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::224:2cff:fe3b:f879/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:509669 errors:0 dropped:0 overruns:0 frame:0
          TX packets:366807 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:715274922 (715.2 MB)  TX bytes:35266765 (35.2 MB)

sriduth@sriduth-HP-G60-Notebook-PC:~$ ping 192.168.1.102
PING 192.168.1.102 (192.168.1.102) 56(84) bytes of data.
64 bytes from 192.168.1.102: icmp_seq=1 ttl=64 time=0.075 ms
64 bytes from 192.168.1.102: icmp_seq=2 ttl=64 time=0.064 ms
^C
--- 192.168.1.102 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 999ms
rtt min/avg/max/mdev = 0.064/0.069/0.075/0.010 ms

sriduth@sriduth-HP-G60-Notebook-PC:~$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.1.254   0.0.0.0         UG    0      0        0 wlan0
10.0.0.0        172.24.4.2      255.255.255.0   UG    0      0        0 br-ex
172.24.4.0      0.0.0.0         255.255.255.0   U     0      0        0 br-ex
192.168.1.0     0.0.0.0         255.255.255.0   U     9      0        0 wlan0
192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

sriduth@sriduth-HP-G60-Notebook-PC:~$ cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback
sriduth@sriduth-HP-G60-Notebook-PC:~$ cat /etc/hosts
127.0.0.1   localhost sriduth-HP-G60-Notebook-PC
127.0.1.1   sriduth-HP-G60-Notebook-PC

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

Solution

With DHCP, computers request IP addresses and networking parameters automatically from a DHCP server, reducing the need for a network administrator or a user to configure these settings manually.

So your eth0 and your wlan0 connection will not all ways have the same ip address it may change each time you disconnect and reconnect to the internet since the ip addresses are assigned automatically.

Eth0 and wlan0 are not assigned by your ip, eth0 and wlan0 are device names assigned by ubuntu.

Eth0 is your ehternet connection and wlan0 is your wireless connection but sometimes wlan0 might be called eth1 instead it all depends on the driver your wireless card is using.

Comments

[Louis Matthijssen]

eth0 is ethernet (cable), wlan0 is wireless LAN (wireless). So, if you're using wireless the IP address belongs to wlan0. Both are not virtual interfaces.