I am about to loose my mind over this. I am using Ubuntu 14.04 LTS on a Lenovo T430s laptop with an Intel 82579lm ethernet card. I can get internet access via wifi (private router) without any problem. If I connect the laptop via an ethernet cable, I do get an IP-adress via DHCP, but I cannot access the internet via browser or ping anything. However, under Windows 7, which is also installed on the laptop, the ethernet connection works perfectly. So I can be sure it is no router or cable problem.
The driver version for the ethernet card (e1000e) is 3.2.6-k.
I've been searching all day for a solution, but nothing actually worked. Anybody has any idea? I'll post any command output needed, just let me know what I can do to help.
Edit: Using ifconfig I get the following output for eth0:
Link encap:Ethernet HWaddr 3c:97:0e:26:37:ab
inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::3e97:eff:fe26:37ab/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:158 errors:0 dropped:0 overruns:0 frame:0
TX packets:495 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:25044 (25.0 KB) TX bytes:57507 (57.5 KB)
So looks like some packets actually go through but no internet connection can be established