Ethernet not working in Ubuntu 14.04

[Dheerendra Rathor]

I am facing a strange problem in my ubuntu. Ethernet is connected but internet is not working . I am attaching various configuration files related to network and output of `ifconfig`. Please help me getting internet back :)

[rahil momin]

Multiple possibilities..

please give output of "route" or "ip route list" to discount some of them.

Also verify is dnsmasq is running by "ps aux | grep -i dnsmasq"

also check if you can ping to a far away system.. like 10.7.10.250 or something

On Mon, Aug 4, 2014 at 6:20 PM, Dheerendra Rathor <dheeru....@gmail.com> wrote:

I am facing a strange problem in my ubuntu. Ethernet is connected but internet is not working . I am attaching various configuration files related to network and output of `ifconfig`. Please help me getting internet back :)

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[Dheerendra Rathor]

Route:
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         10.9.40.250     0.0.0.0         UG    0      0        0 eth0
10.9.32.0       *               255.255.224.0   U     1      0        0 eth0

IP route list:
default via 10.9.40.250 dev eth0  proto static
10.9.32.0/19 dev eth0  proto kernel  scope link  src 10.9.32.54  metric 1

dnsmasq:
nobody    1503  0.0  0.0  35224  1536 ?        S    01:06   0:00 /usr/sbin/dnsmasq --no-resolv --keep-in-foreground --no-hosts --bind-interfaces --pid-file=/run/sendsigs.omit.d/network-manager.dnsmasq.pid --listen-address=127.0.1.1 --conf-file=/var/run/NetworkManager/dnsmasq.conf --cache-size=0 --proxy-dnssec --enable-dbus=org.freedesktop.NetworkManager.dnsmasq --conf-dir=/etc/NetworkManager/dnsmasq.d

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From: rahil momin
Sent: ‎04-‎08-‎2014 07:35 PM
To: wncc...@googlegroups.com
Subject: Re: [WnCC] Ethernet not working in Ubuntu 14.04

[rahil momin]

The routes look fine (I can't confirm though)

Can you ping to 10.7.10.250 , 10.9.40.250 or any other system?

if yes, then it may be a dns issue.. or proxy

[Harsh Gupta]

Can you post the output of `lspci | grep -i ethernet` it will show the
name of your ethernet hardware. Then you should search on the web if
your hardware is supported.

Harsh

[Dheerendra Rathor]

Both pings are fine. 0% packet loss.

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From: rahil momin
Sent: ‎04-‎08-‎2014 07:50 PM

[Pritam Baral]

@Harsh: Inapplicable.

@Dheerendra, if your system can reach both 10.{7,9}.10.250 with 0% packet loss, it can reach netmon.iitb perfectly fine too.
Either use netmon.iitb.ac.in as a proxy, or log in to internet.iitb.ac.in. If problem persists, the next level of diagnostics should be firewall (post output of sudo iptables-save).

 

Regards,
Chhatoi Pritam Baral

[rahil momin]

If ping is working, then its most likely a DNS/Proxy issue.

Check if you can go to internet.iitb.ac.in
if not:

TEMPORARY SOLUTION:
edit /etc/resolv.conf as root

"gksudo gedit /etc/resolv.conf"

replace 127.0.0.1 or whatever with 10.200.1.11

save, exit.. check if internet.iitb.ac.in is now available (without touching the LAN cable)

if you can do that, you have to permanently set dns in network settings and/or change dnsmasq configs (or edit this file everytime you touch the Lan cable :P)

Check if you are using proxy.

[Pritam Baral]

@Rahil: disabling dnsmasq permanently is simple: remove it from /etc/NetworkManager.conf.

[Dheerendra Rathor]

I don't think hardware is an issue. It was working fine 2 days ago. Btw it is RTL8101E/RTL8102E PCI express fast Ethernet controller

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From: Harsh Gupta
Sent: ‎04-‎08-‎2014 08:06 PM

[Dheerendra Rathor]

@pritam sudo iptables-save is returning nothing. Netmon and internet.iitb.ac.in both are not working
@rahil changing nameserver is also not working

I just noticed a strange thing that wireshark is listing only Bluetooth as only available interface for capturing

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From: Pritam Baral
Sent: ‎04-‎08-‎2014 08:11 PM

To: wncc...@googlegroups.com
Subject: Re: [WnCC] Ethernet not working in Ubuntu 14.04

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[Pritam Baral]

Empty iptables-save, so firewall is clean. When you say internet.iitb.ac.in is "not working", do you mean the page can't be opened, or that you don't have internet even after logging in?

In any case, post the output of

wget goo.gl -O /dev/null

^This will most certainly let us know where exactly the problem lies.

BTW, wireshark is showing that probably because it wasn't started as root.

[Dheerendra Rathor]

problem solved temporarily:

when i tried to restart dnsmasq by 'sudo /etc/init.d/dnsmasq restart' it shows error dnsmasq: unknown interface wlan0

Since  I am using ap-hotspot for creating wifi, i tried to debug that and ran ap-hotspot in debug mode and i got the output:

* Stopping DNS forwarder and DHCP server dnsmasq

* (not running)

update-rc.d: warning:  start runlevel arguments (none) do not match hostapd Default-Start values (2 3 4 5)

update-rc.d: warning:  stop runlevel arguments (none) do not match hostapd Default-Stop values (0 1 6)

Disabling system startup links for /etc/init.d/hostapd ...

Removing any system startup links for /etc/init.d/hostapd ...

/etc/rc0.d/K20hostapd

/etc/rc1.d/K20hostapd

/etc/rc2.d/K80hostapd

/etc/rc3.d/K80hostapd

/etc/rc4.d/K80hostapd

/etc/rc5.d/K80hostapd

/etc/rc6.d/K20hostapd

Adding system startup for /etc/init.d/hostapd ...

/etc/rc0.d/K20hostapd -> ../init.d/hostapd

/etc/rc1.d/K20hostapd -> ../init.d/hostapd

/etc/rc6.d/K20hostapd -> ../init.d/hostapd

/etc/rc2.d/K80hostapd -> ../init.d/hostapd

/etc/rc3.d/K80hostapd -> ../init.d/hostapd

/etc/rc4.d/K80hostapd -> ../init.d/hostapd

/etc/rc5.d/K80hostapd -> ../init.d/hostapd

update-rc.d: warning:  start runlevel arguments (none) do not match dnsmasq Default-Start values (2 3 4 5)

update-rc.d: warning:  stop runlevel arguments (none) do not match dnsmasq Default-Stop values (0 1 6)

Disabling system startup links for /etc/init.d/dnsmasq ...

Removing any system startup links for /etc/init.d/dnsmasq ...

/etc/rc0.d/K85dnsmasq

/etc/rc1.d/K85dnsmasq

/etc/rc2.d/K85dnsmasq

/etc/rc3.d/K85dnsmasq

/etc/rc4.d/K85dnsmasq

/etc/rc5.d/K85dnsmasq

/etc/rc6.d/K85dnsmasq

Adding system startup for /etc/init.d/dnsmasq ...

/etc/rc0.d/K85dnsmasq -> ../init.d/dnsmasq

/etc/rc1.d/K85dnsmasq -> ../init.d/dnsmasq

/etc/rc6.d/K85dnsmasq -> ../init.d/dnsmasq

/etc/rc2.d/K85dnsmasq -> ../init.d/dnsmasq

/etc/rc3.d/K85dnsmasq -> ../init.d/dnsmasq

/etc/rc4.d/K85dnsmasq -> ../init.d/dnsmasq

/etc/rc5.d/K85dnsmasq -> ../init.d/dnsmasq

* Restarting DNS forwarder and DHCP server dnsmasq

...done.

/etc/resolvconf/update.d/libc: Warning: /etc/resolv.conf is not a symbolic link to /run/resolvconf/resolv.conf

net.ipv4.ip_forward = 1

Wireless Hotspot active

and after that i was able to login to internet.iitb.ac.in

Now the problem is first I have to start ap-hotspot (wireless got auto enabled at startup) then i can use internet.

and as soon I stop ap-hotspot internet goes down.

On 5 August 2014 02:32, Dheerendra Rathor <dheeru....@gmail.com> wrote:

when tried to open internet.iitb.ac.in, chrome shows unable to connect to internet. While using netmon in Firefox it doesn't prompt for authentication and return unable to find proxy server.

Output of wget goo.gl :
http://goo.gl/ resolving goo.gl (goo.gl)... Failed: Name or service not known.
Wget: Unable to resolve host address 'goo.gl'

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From: Pritam Baral
Sent: ‎04-‎08-‎2014 10:00 PM

To: wncc...@googlegroups.com
Subject: Re: [WnCC] Ethernet not working in Ubuntu 14.04

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[Dheerendra Rathor]

when tried to open internet.iitb.ac.in, chrome shows unable to connect to internet. While using netmon in Firefox it doesn't prompt for authentication and return unable to find proxy server.

Output of wget goo.gl :
http://goo.gl/ resolving goo.gl (goo.gl)... Failed: Name or service not known.
Wget: Unable to resolve host address 'goo.gl'

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From: Pritam Baral
Sent: ‎04-‎08-‎2014 10:00 PM

To: wncc...@googlegroups.com
Subject: Re: [WnCC] Ethernet not working in Ubuntu 14.04

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