1

for two days, my laptop cannot connect to the internet (a.k.a. all machines beyond my router) anymore. I have investigated the following things:

  1. The network access worked fine half a week ago.
  2. I have no idea, what could have caused the outage.
  3. System: Ubuntu 14.04, XFCE, fully patched
  4. I can access just fine the router's web interface and even other machines in my home net
  5. I cannot reach any server outside, neither by name nor by IP.
  6. I added Google's 8.8.8.8 as DNS resolver, no change (no surprise after finding 5...)
  7. ufw is disabled:

    $ sudo ufw status
    WARN: Doppeltes Profil 'Apache', zuletzt gefundenes wird verwendet
    WARN: Doppeltes Profil 'Apache Secure', zuletzt gefundenes wird verwendet
    WARN: Doppeltes Profil 'Apache Full', zuletzt gefundenes wird verwendet
    Status: Inaktiv
    
  8. iptables have no strange entries:

    $ sudo iptables-save
    *filter
    :INPUT ACCEPT [240:30526]
    :FORWARD ACCEPT [0:0]
    :OUTPUT ACCEPT [2994769:4696400653]
    COMMIT
    
  9. I checked with the router, there is no active firewall there. Also all other computers, each running Ubuntu, can connect to the net just fine.

  10. There's no difference between eth0 and wlan0, both do not work.

  11. ifconfig output:

    $ ifconfig
    eth0      Link encap:Ethernet  HWaddr 00:17:a4:e8:2a:9c  
              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)
              Interrupt:18 
    
    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:229 errors:0 dropped:0 overruns:0 frame:0
              TX packets:229 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:0 
              RX bytes:30871 (30.8 KB)  TX bytes:30871 (30.8 KB)
    
    tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
              inet addr:10.8.0.6  P-t-P:10.8.0.5  Mask:255.255.255.255
              UP POINTOPOINT RUNNING NOARP 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:100 
              RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
    
    wlan0     Link encap:Ethernet  HWaddr 00:1b:77:34:2f:09  
              inet addr:192.168.178.23  Bcast:192.168.178.255  Mask:255.255.255.0
              inet6 addr: fe80::21b:77ff:fe34:2f09/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:188 errors:0 dropped:0 overruns:0 frame:0
              TX packets:262 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000 
              RX bytes:27175 (27.1 KB)  TX bytes:35542 (35.5 KB)
    
  12. Output of route -n:

    $ route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         10.8.0.5        128.0.0.0       UG    0      0        0 tun0
    0.0.0.0         192.168.178.1   0.0.0.0         UG    0      0        0 wlan0
    10.0.0.0        10.8.0.5        255.255.255.0   UG    0      0        0 tun0
    10.8.0.1        10.8.0.5        255.255.255.255 UGH   0      0        0 tun0
    10.8.0.5        0.0.0.0         255.255.255.255 UH    0      0        0 tun0
    128.0.0.0       10.8.0.5        128.0.0.0       UG    0      0        0 tun0
    188.192.138.205 192.168.178.1   255.255.255.255 UGH   0      0        0 wlan0
    192.168.178.0   0.0.0.0         255.255.255.0   U     9      0        0 wlan0
    

I am basically at my wits' end now. What can I try to bring the laptop back to connecting to the 'Net? Any diagnosis data that you need will be given with pleasure.

3
  • If you can open your router's interface, you have an IP address. If you can't access anything outside the LAN network, you probably don't have a default gateway set. What's the output of route -n?
    – Alaa Ali
    Aug 4, 2014 at 21:08
  • I added the output to the question. However, the result looks similar to my working desktop computer.
    – Boldewyn
    Aug 4, 2014 at 21:15
  • 1
    Turn of VPN temporarily and it will work.
    – initall
    Aug 4, 2014 at 21:16

3 Answers 3

2

Try this:

# stop network manager
sudo /etc/init.d/NetworkManager stop
# if on a cable connection, re-run with dhcp
sudo ip link set dev eth0 down
sudo dhclient eth0
# try to ping via ip first
ping 8.8.8.8

(Update after ifconfig output)

Currently you use wlan, just to make sure plug in a caple and re-check with eth0 and DHCP. There must be a default route to the gateway as was noted in a comment, e.g.

 sudo ip route add default via 192.168.178.1
3
  • Hm. There is no /etc/init.dNetworkManager. The closest is /etc/init.d/networking.
    – Boldewyn
    Aug 4, 2014 at 21:18
  • Yep, that's it. service openvpn stop did it. Any idea, where it went wrong?
    – Boldewyn
    Aug 4, 2014 at 21:20
  • (Außerdem solltest du dich erholen, nicht private IT-Probleme von Mitarbeitern lösen :-P )
    – Boldewyn
    Aug 4, 2014 at 21:20
1

Try this:

  1. Click on the network symbol on the top right → Edit Connections:

  2. Highlight your VPN connection → Edit.

  3. Go to IPv4 SettingsRoutes... and check Use this connection only for resources on its network and save. Then try accessing the internet.

2
  • 1
    Thanks for the answer. I haven't tried it yet, since I'm not near the machine right now. Apparently it was the VPN going rogue. Would that be covered by your method?
    – Boldewyn
    Aug 5, 2014 at 7:20
  • 1
    @Boldewyn, yes, my answer will instruct your machine to send traffic whose IP addresses fall under the VPN through the VPN connection, and anything else through your normal wireless connection. This method will allow you to browse the internet normally while still connected to the VPN.
    – Alaa Ali
    Aug 5, 2014 at 9:05
0

what does your

 ifconfig

says?

do you get ip ? is your adapter configured for DHCP? is your router DHCP server enabled?

1
  • 1
    Yes, I get my IP address just fine. I update the question with ifconfig output.
    – Boldewyn
    Aug 4, 2014 at 21:07

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