Laptop can't connect to wired internet

Question

Ubuntu 14.04. It detects wired connections but can't get an IP address. I've tried it with different wired networks and each time had the same problem, both with nm-applet and wicd. My other computer connects to my home network without a problem.

It's not blocked, soft or hard. I tried the suggestion here but it didn't change anything. One thing to note is that cable does not connect directly to the laptop but through a proprietary connector. Here is the output of ifconfig:

eth0      Link encap:Ethernet  HWaddr 24:f5:aa:c2:58:c7  
          inet6 addr: fe80::26f5:aaff:fec2:58c7/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:378 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

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:65536  Metric:1
          RX packets:8058 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8058 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:2163118 (2.1 MB)  TX bytes:2163118 (2.1 MB)

wlan0     Link encap:Ethernet  HWaddr 6c:29:95:19:08:1b  
          inet addr:192.168.1.133  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::6e29:95ff:fe19:81b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2280079 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1500378 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2912209727 (2.9 GB)  TX bytes:186227404 (186.2 MB)

Here is the contents of /etc/network/interfaces

# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet dhcp

Here is the output of sudo lspci -vvnn | grep -iA 10 ethernet.

03:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev 0c)
    Subsystem: Samsung Electronics Co Ltd Device [144d:c109]
    Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
    Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
    Latency: 0, Cache Line Size: 64 bytes
    Interrupt: pin A routed to IRQ 61
    Region 0: I/O ports at e000 [size=256]
    Region 2: Memory at f7c00000 (64-bit, non-prefetchable) [size=4K]
    Region 4: Memory at f0000000 (64-bit, prefetchable) [size=16K]
    Capabilities: [40] Power Management version 3
        Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=375mA PME(D0+,D1+,D2+,D3hot+,D3cold+)

have you already made a reset with your modem (cable-modem or w-lan modem?) - the modem has a reset-button and you could push this little button cautiously for 3 or 5 seconds. — dschinn1001, Mar 19 '16 at 03:17
@Reza is your Ethernet supposed to only be trying to get IPv6? — TheWanderer, Mar 21 '16 at 00:44
I don't think so. As I said I've tried it with several different networks. — Reza, Mar 21 '16 at 00:50
You need to tell more about the proprietary connector. Is it a Ethernet to USB adapter? — daltonfury42, Mar 21 '16 at 04:44
@Reza Does this installation have a GUI? I think you should go into System Settings >> Network >> Ethernet >> Options and make sure IPv4 is available. — TheWanderer, Mar 21 '16 at 12:42
Are you using a compatible driver for your network card? Can you provide the output of lspci -nnk | grep Ether -A2 ? — lamino, Mar 21 '16 at 14:24

score 1 · Answer 1 · edited Mar 22 '16 at 14:54

1

set network configuration manually. for that, follow the below commands:

ifconfig eth0 192.168.31.3 netmask 255.255.255.0 up

(IP and NetMask is example)

sevice networking restart

edited Mar 22 '16 at 14:54

Byte Commander

107,489

answered Mar 21 '16 at 02:02

ansar313

159
2
8

Ah it seems to work! But why automatics configuration didn't wotk? – Reza Mar 22 '16 at 01:12
It worked for the first time but not anymore. – Reza Mar 22 '16 at 12:12
use dhcp by following command:dhclient -v and thenservice networking restart. if it doesn't work you must make a complete network troubeshoting – ansar313 Mar 23 '16 at 10:03

score 1 · Answer 2 · edited Mar 24 '16 at 12:57

1

Add in /etc/network/interfaces

(this is example)

iface eth0 inet static
address 192.168.1.200
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1

Then

sudo /etc/init.d/networking restart

This way use static IP address.

edited Mar 24 '16 at 12:57

Mostafa Ahangarha

4,408

answered Mar 22 '16 at 16:04

Junshoong

11

I did so and applied the same settings in nm-connection-editor. It connects but I can't access the internet. Should I apply the same settings (for my laptop) in my router as well? – Reza Mar 23 '16 at 10:03
Can you not resolve addresses, or you can't connect to any external IPs? For example, ping google.com doenst work, but ping 8.8.8.8 does? If so, add 'dns-nameservers 192.168.1.1' to the eth0 interface config. As you're just missing name resolution. – Mar 24 '16 at 14:37
Thanks for your input however if I only edit that file the nm-applet or wicd still can't get an IP address. I can edit the connection in the applet to have manual IP but then I don't think this will work for other wired network and my question was why Ubuntu can't get the IP address while the same computer with windows can. – Reza Mar 25 '16 at 12:06

Laptop can't connect to wired internet

2 Answers2