Is there any way for you to verify the internet connection itself? To me, it sounds like this is an ISP related problem and not Linux, because Linux detected your network card.

Tests you can try:

Ping:
(Should return packets, "cannot look up host" is a sign the network's down. Quit with CTRL-C.)

Refreshing DHCP:
Where eth0 is your network card. Requires root access.

If you've got a router, you may want to try a DHCP refresh on that to, and check the network status of both your WAN and LAN. Make sure everything looks OK.

The ping command said "Unknown host"

I am using Realtek (RTL) 8139c as my network card.

Here what I got when I tried:


/sbin/ifconfig -a

eth0 Link encap:Ethernet HWaddr 00:C0:9F:BB:BA:57
inet addr:169.254.75.254 Bcast:169.254.255.255 Mask:255.255.0.0
inet6 addr: fe80::2c0:9fff:febb:ba57/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:41 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:5384 (5.2 KiB)
Interrupt:6

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:2154 errors:0 dropped:0 overruns:0 frame:0
TX packets:2154 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:2756707 (2.6 MiB) TX bytes:2756707 (2.6 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)

-------------------------------------------------------------------------------------

# /sbin/route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 lo
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0

I do not understand what it says in return though. After applying the above said 2 commands in the terminal. Can you help me, this is really weird. All was fine until 3-4 days ago. Thanks.

Your DHCP is acting up. IP addresses of 169.254.*.* indicate that the address was the result of a failed attempt to get an IP address with the dhcpcd command.

If dhcpcd doesn't change your IP address from 169.254.*.*, then you should definitely contact your ISP as it seems like this is something to do with your ISP. Especially the fact that you said you didn't change anything; it's most likely you didn't.

Thanks, so it means that whenever ones gets an ip address like 169.254.*.* there has been a problem with the internet connection right? I just searched online and came across this page

http://en.wikipedia.org/wiki/Private_network

If you scroll down to the bottom of it, there is one line which says

That means you are right. Cheers I will contacct my isp asap. Cheers.