Ubuntu – No internet in Ubuntu 14.04

I use Windows 10 and Ubuntu 14.04 on my laptop. I am able to access internet (wired and WiFi) on my laptop when I use Windows 10 but not with Ubuntu 14.04. The modem is working perfectly fine, there is no problem with modem, however when I open Firefox in Ubuntu I get an error "server not found". I am not able to use internet through wired or WiFi connection in Ubuntu.

$ lspci -knn | grep -EA3 'Eth|Net'
09:00.0 Network controller [0280]: Intel Coropration Centrino Wireless-N 1030 [Rainbow Peak]
[8086:008b] (rev34)
            Subsystem: Intel Coropration Centrino Wireless-N 1030 BGN [8086:5315]
            Kernel driver in use: iwlwifi
0a:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5209 PCI Express Card
Reader [10ec:5209] (rev 01)
--
10:00.0 Ethernet controller [0200]: Qualcomm Atheros AR8151 v2.0 Gigabit Ethernet [1969:1083]
(rev c0)
           Subsystem: Hewlett-Packard Company Device [103c:1651]
           Kernel driver in use: atlid

$ rfkill list
0: hci0: Bluetooth
            Soft blocked: no
            Hard blocked: no
1: phy0: Wireless LAN
            Soft blocked: no
            Hard blocked: no

dmesg | grep iwl: