[SOLVED] Linux Network Connectivity Problem; Dual Boot, Works on Windows, not Ubuntu

coderlen · 09-11-2019, 10:03 AM

I have a dual boot laptop, Ubuntu 18.0.4, and Windows 10. The Windows side has no problem with Internet connectivity, but the Linux side does. Ubuntu shows the wired and wireless network connectivity as OK, but there is no Internet access.

I am posting here a pdf file of the screen prints. Sorry, I couldn't figure out any other way to do it. Here is the link to the screen prints:

Screen Prints of Network-Internet Connectivity Issue 2019-09-11.pdf

Let me know if I need to post anything else. Thanks.

Firerat · 09-11-2019, 10:55 AM

internet is working, your dns resolver is not

can you provide output of

Code:

cat /etc/resolv.conf

text please the pdf is nice but the ping results could have been pasted here in a code box like this

[code]
paste here
[/code]

coderlen · 09-11-2019, 01:55 PM

Firerat, thanks for your response. I have logged onto the Linux side and done as you requested. But the results are not as you might expect.

I did a little digging, and I have once again included some pdf screen prints. I think it tells the story better than I can. Take a look and see. The /etc/resolv,conf is not found.

I will have to post back here later. The filesize of the pdf was too large.

Firerat · 09-11-2019, 02:18 PM

well

you typed /etc/resolv,conf with a comma , not a fullstop . ( period in US? )
if that was typed on the command line that is why it was not found.

you should be able to copy and paste the output from the command line

edit: I just realised, no internet

so can not copy paste?
instead of using a pdf you could save output to a text file and copy paste that

Firerat · 09-11-2019, 02:55 PM

ok, I'm going to try to pre-empt things

Network Manager should be handling the DNS setup

I'm going to try and guide you through adding 8.8.8.8 ( opendns )

Code:

sudo nmtui
#-> Edit Connection
#-> select your wifi
#-> IPv4 CONFIGURATION <Automatic> <Show>
#-> If not Automatic select that and pick auto
#-> select <show> 
#-> DNS servers ->  <add>
# enter 8.8.8.8
# [X] Ignore automatically obtained DNS parameters
# if it is marked X as above
# select the X and toggle with <spacebar>
# actually, may not need the 8.8.8.8 if ignore was checked
# optionally repeat with IPv6
# down at bottom select OK

reconnect the wifi, you should be able to resolve dns names
we then need to work out if we can add a better one from your router/ISP
although... many people choose to use 8.8.8.8

michaelk · 09-11-2019, 04:05 PM

As a FYI, Ubuntu 18 uses systemd-resolved as a DNS resolver by default so /etc/resolv.conf should look something like

Code:

nameserver 127.0.0.53
options ...
...

Is your system configured for DHCP? Have you changed any network settings? Connecting to a VPN?

What is the output of the command
systemd-resolve --status

You can use the command line as posted or the NetworkManager applet might be easier to use.

coderlen · 09-11-2019, 09:27 PM

Firerat and michaelk, I appreciate your responses, in spite of my busy schedule and not being able to follow up. I will take your suggestions and try them as soon as I complete this post.

OK. Since /etc/resolv.conf was not found, I changed directories to the /etc directory, and keyed in "ls -al". This is part of what Linux spit out:

Code:

drwxr-xr-x   2 root root    4096 Apr 27  2018 rcS.d
drwxr-xr-x   3 root root    4096 Apr 26  2018 resolvconf
lrwxrwxrwx   1 root root      27 Sep 10 22:46 resolv.conf -> /run/resolvconf/resolv.conf
-rwxr-xr-x   1 root root     268 Jul 21  2017 rmt

So I decided to keep digging.

Code:

len@len-Satellite-E45t-A:/etc$ cd resolvconf/
len@len-Satellite-E45t-A:/etc/resolvconf$ ls -al
total 20
drwxr-xr-x   3 root root    4096 Apr 26  2018 .
drwxr-xr-x 139 root root   12288 Sep 10 22:46 ..
drwxr-xr-x   2 root root    4096 Feb  6  2019 update-libc.d
len@len-Satellite-E45t-A:/etc/resolvconf$ cd update-libc.d/
len@len-Satellite-E45t-A:/etc/resolvconf/update-libc.d$ ls -al
total 12
drwxr-xr-x   2 root root    4096 Feb  6  2019 .
drwxr-xr-x   3 root root    4096 Apr 26  2018 ..
-rwxr-xr-x   1 root root     249 Feb  2  2018 avahi-daemon
len@len-Satellite-E45t-A:/etc/resolvconf/update-libc.d$

Doesn't look like resolv.conf is working like you would expect.

So now I will try your suggestions, and I'll post back here later.

Firerat · 09-11-2019, 10:16 PM

/etc/resolv.conf does exist
it is a link to /run/resolvconf/resolv.conf

but cat wouldn't care ... or maybe it would..
ok if the link was broken it would say "No such file or directory"

Code:

ls /run/resolvconf/
# note that is /run not /etc

we are looking for resolv.conf

I would double check
it is really easy to miss type it as resolve.conf

Code:

cat /etc/resolv.conf

tip: when using command line, you can use something called tab completion
<tab> is the tab key

Code:

cat /e<tab>res<tab>.<tab>

^^ that would be enough to get the whole command
handy for looking for things that you don't quite know the name of, a double tab give a list of possible completions

coderlen · 09-11-2019, 10:58 PM

Firerat, to answer your previous question, I did indeed post "/etc/resolv,conf", but I really did type "/etc/resolv.conf" at the command line. I just didn't proofread the post.

And I did try your suggestion for using Network Manager. That's a pretty nifty little tool, thanks for informing me about it. However, that did not fix the problem. And I was very careful to not spell it "resolve", I used "resolv". I did know about using tab for command-completion. But thanks, it never hurts to get more knowledge.

michaelk, here is the output of "systemd-resolve --status":

Code:

len@len-Satellite-E45t-A:~$ systemd-resolve --status
Global
          DNSSEC NTA: 10.in-addr.arpa
                      16.172.in-addr.arpa
                      168.192.in-addr.arpa
                      17.172.in-addr.arpa
                      18.172.in-addr.arpa
                      19.172.in-addr.arpa
                      20.172.in-addr.arpa
                      21.172.in-addr.arpa
                      22.172.in-addr.arpa
                      23.172.in-addr.arpa
                      24.172.in-addr.arpa
                      25.172.in-addr.arpa
                      26.172.in-addr.arpa
                      27.172.in-addr.arpa
                      28.172.in-addr.arpa
                      29.172.in-addr.arpa
                      30.172.in-addr.arpa
                      31.172.in-addr.arpa
                      corp
                      d.f.ip6.arpa
                      home
                      internal
                      intranet
                      lan
                      local
                      private
                      test

Link 3 (wlp3s0)
      Current Scopes: DNS
       LLMNR setting: yes
MulticastDNS setting: no
      DNSSEC setting: no
    DNSSEC supported: no
         DNS Servers: 192.168.1.1
          DNS Domain: ~.
                      zyxel.com

Link 2 (enp2s0)
      Current Scopes: none
       LLMNR setting: yes
MulticastDNS setting: no
      DNSSEC setting: no
    DNSSEC supported: no
lines 9-45/45 (END)

I have done some of my own research on the Internet. One suggestion was to use the iptables command to check if the connection is getting blocked by a firewall. Here is the result:

Code:

len@len-Satellite-E45t-A:~$ sudo iptables -L
[sudo] password for len: 
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
len@len-Satellite-E45t-A:~$

Here is a tracepath command, which supposedly helps show where the connection fails:

Code:

len@len-Satellite-E45t-A:~$ tracepath 8.8.8.8
 1?: [LOCALHOST]                      pmtu 1500
 1:  _gateway                                              2.507ms 
 1:  _gateway                                             18.019ms 
 2:  10.202.0.1                                           16.771ms 
 3:  10.192.110.170                                       15.217ms 
 4:  69.174.129.152                                       19.683ms 
 5:  no reply
 6:  no reply
 7:  no reply
 8:  no reply
 9:  no reply
10:  no reply
11:  no reply
12:  no reply
^Z
[1]+  Stopped                 tracepath 8.8.8.8
len@len-Satellite-E45t-A:~$

And finally, some ping commands:

Code:

len@len-Satellite-E45t-A:~$ ping www.ubuntu.com
ping: www.ubuntu.com: Name or service not known
len@len-Satellite-E45t-A:~$ ping www.microsoft.com
ping: www.microsoft.com: Name or service not known
len@len-Satellite-E45t-A:~$ ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=2.02 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=3.69 ms
64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=3.34 ms
64 bytes from 192.168.1.1: icmp_seq=4 ttl=64 time=3.23 ms
64 bytes from 192.168.1.1: icmp_seq=5 ttl=64 time=6.46 ms
64 bytes from 192.168.1.1: icmp_seq=6 ttl=64 time=3.32 ms
64 bytes from 192.168.1.1: icmp_seq=7 ttl=64 time=3.28 ms
64 bytes from 192.168.1.1: icmp_seq=8 ttl=64 time=3.30 ms
64 bytes from 192.168.1.1: icmp_seq=9 ttl=64 time=2.69 ms
64 bytes from 192.168.1.1: icmp_seq=10 ttl=64 time=2.65 ms
64 bytes from 192.168.1.1: icmp_seq=11 ttl=64 time=2.82 ms
64 bytes from 192.168.1.1: icmp_seq=12 ttl=64 time=2.74 ms
64 bytes from 192.168.1.1: icmp_seq=13 ttl=64 time=2.66 ms
^Z
[2]+  Stopped                 ping 192.168.1.1
len@len-Satellite-E45t-A:~$ ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=56 time=10.9 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=56 time=10.8 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=56 time=11.8 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=56 time=11.4 ms
64 bytes from 8.8.8.8: icmp_seq=5 ttl=56 time=13.8 ms
64 bytes from 8.8.8.8: icmp_seq=6 ttl=56 time=9.86 ms
64 bytes from 8.8.8.8: icmp_seq=7 ttl=56 time=12.7 ms
^Z
[3]+  Stopped                 ping 8.8.8.8
len@len-Satellite-E45t-A:~$

Hopefully, this will give you a lot of data to help me solve this problem. Hey, I really appreciate your help. I just don't have enough experience on Linux yet, so I regard your counsel as invaluable.

Firerat · 09-11-2019, 11:10 PM

what is in /run/resolvconf/
that is where /etc/resolv.conf is pointing to

Quote:

Originally Posted by Firerat

/etc/resolv.conf does exist
it is a link to /run/resolvconf/resolv.conf
<snip>

Code:

ls /run/resolvconf/
# note that is /run not /etc

we are looking for resolv.conf
<snip>

coderlen · 09-11-2019, 11:30 PM

Firerat, the /run directory does not contain a file or even a directory named "resolvconf". Perhaps that is important! That link is pointing to a non-existent file.

Firerat · 09-11-2019, 11:50 PM

yeap

when anything writes to /etc/resolv.conf it just disappears into a blackhole

ok, we can work around it.. until we figure out what is failing to create it

Code:

sudo mkdir /run/resolvconf

if you then reconnect with wifi it *should* populate the resolv.conf

this won't persist.
/run is a tmpfs it only exists in memory
once you reboot it will be gone

Firerat · 09-12-2019, 01:41 AM

after installing ubuntu bionic in a lxc I get

Code:

ls -l /etc/resolv.conf 
lrwxrwxrwx 1 root root 39 Sep 11 07:43 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf

note the date,
this would have been when the lxc image was created.

I deleted that file and rebooted ( the lxc )
it was not recreated.

after ln -s back to the stub
I installed resolvconf

Code:

apt install resolvconf
ls /etc/resolv.conf -l
lrwxrwxrwx 1 root root 29 Sep 12 05:54 /etc/resolv.conf -> ../run/resolvconf/resolv.conf

the contents were similar those in original /etc/resolv.conf
( "options edns0" line was removed ) see +bug/1817903

I then rebooted the lxc, and re listed

Code:

ls -l /etc/resolv.conf /run/resolvconf/
lrwxrwxrwx 1 root root  29 Sep 12 05:54 /etc/resolv.conf -> ../run/resolvconf/resolv.conf

/run/resolvconf/:
total 4
-rw-r--r-- 1 root root   0 Sep 12 05:59 enable-updates
drwxr-xr-x 2 root root  60 Sep 12 05:59 interface
-rw-r--r-- 1 root root 315 Sep 12 05:59 resolv.conf

The time stamp had not changed on /etc/resolv.conf
however, the time stamps in /run/resolvconf reflect the boot time

so, it would appear something has gone wrong with resolvconf
around Sep 10 22:46 , do you recall doing any installs/updates around that time?
the changelog for resolvconf shows no recent activity
last being

Code:

resolvconf (1.79ubuntu10.18.04.3) bionic; urgency=medium

  * d/resolvconf.resolvconf-pull-resolved.service
    Hack out the 'edns0' option that systemd-resolved has
    recently added to its stub-resolv.conf. (LP: #1817903)

 -- Dan Streetman <ddstreet@canonical.com>  Thu, 14 Mar 2019 17:35:23 -0400

options

reinstall resolvconf
Code:
```
sudo apt install resolvconf --reinstall
```
uninstall resolvconf and return to ubuntu bionic default
Code:
```
sudo apt purge resolvconf
```

Unless you recall a specific reason for having resolvconf I would go down the uninstall route.
It could be that resolvconf resolved the issue which +bug/1817903 refers to, in which case try the reinstall

if neither of those options work then I may have to track down what the ifupdown that is mentioned in bug/1817903 is/was doing

was this system upgraded to 18 or was it installed as 18?

coderlen · 09-12-2019, 09:37 AM

Firerat, here's a report for you. Thanks for your help.

Quote:

so, it would appear something has gone wrong with resolvconf
around Sep 10 22:46 , do you recall doing any installs/updates around that time?

Yes, I did this:

Code:

sudo nano /etc/network/interfaces

and then I added these lines to the "interfaces" file:

Code:

auto eth0
iface eth0 inet dhcp

auto eth1
iface eth1 inet dhcp

I also stopped, started, restarted the network services with these commands

Code:

sudo ifdown eth0 && sudo ifup eth0

I tried some other variants of "ifdown" and "ifup", can't remember now exactly. I was trying to get the network services to stop and restart.

I did the following, per your instructions:

Code:

len@len-Satellite-E45t-A:~$ sudo mkdir /run/resolvconf
[sudo] password for len: 
len@len-Satellite-E45t-A:~$ ls -l /etc/resolv.conf
lrwxrwxrwx 1 root root 27 Sep 10 22:46 /etc/resolv.conf -> /run/resolvconf/resolv.conf
len@len-Satellite-E45t-A:~$ sudo apt purge resolvconf
[sudo] password for len: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package 'resolvconf' is not installed, so not removed
The following packages were automatically installed and are no longer required:
  activity-log-manager libgeonames-common libgeonames0 libllvm6.0:i386
  libllvm7 libllvm7:i386 libnm-gtk0 libqt5quickwidgets5 libsimgearcore2018.2.2
  libsimgearscene2018.2.2 libtimezonemap-data libtimezonemap1
  libunity-control-center1
Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.
len@len-Satellite-E45t-A:~$ sudo apt autoremove
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages will be REMOVED:
  activity-log-manager libgeonames-common libgeonames0 libllvm6.0:i386
  libllvm7 libllvm7:i386 libnm-gtk0 libqt5quickwidgets5 libsimgearcore2018.2.2
  libsimgearscene2018.2.2 libtimezonemap-data libtimezonemap1
  libunity-control-center1
0 upgraded, 0 newly installed, 13 to remove and 2 not upgraded.
After this operation, 217 MB disk space will be freed.
Do you want to continue? [Y/n] Y
(Reading database ... 275565 files and directories currently installed.)
Removing activity-log-manager (0.9.7-0ubuntu26) ...
Removing libgeonames0:amd64 (0.2+17.04.20170220-0ubuntu1) ...
Removing libgeonames-common (0.2+17.04.20170220-0ubuntu1) ...
Removing libllvm6.0:i386 (1:6.0-1ubuntu2) ...
Removing libllvm7:amd64 (1:7-3~ubuntu0.18.04.1) ...
Removing libllvm7:i386 (1:7-3~ubuntu0.18.04.1) ...
Removing libnm-gtk0:amd64 (1.8.10-2ubuntu2) ...
Removing libqt5quickwidgets5:amd64 (5.9.5-0ubuntu1.1) ...
Removing libsimgearscene2018.2.2:amd64 (1:2018.2.2-0ubuntu1~ppa1~18.04.1) ...
Removing libsimgearcore2018.2.2:amd64 (1:2018.2.2-0ubuntu1~ppa1~18.04.1) ...
Removing libtimezonemap1:amd64 (0.4.5) ...
Removing libtimezonemap-data (0.4.5) ...
Removing libunity-control-center1 (15.04.0+18.04.20180216-0ubuntu1) ...
Processing triggers for desktop-file-utils (0.23-1ubuntu3.18.04.2) ...
Processing triggers for bamfdaemon (0.5.3+18.04.20180207.2-0ubuntu1) ...
Rebuilding /usr/share/applications/bamf-2.index...
Processing triggers for libc-bin (2.27-3ubuntu1) ...
Processing triggers for gnome-menus (3.13.3-11ubuntu1.1) ...
Processing triggers for hicolor-icon-theme (0.17-2) ...
Processing triggers for mime-support (3.60ubuntu1) ...
len@len-Satellite-E45t-A:~$

Still, the network is down. No joy.

Firerat · 09-12-2019, 10:26 AM

was this before or after problems?

eth0 is 'the old way' of naming network devices

also you are using Network Manager, you don't need to manually setup network with that configuration

Code:

ip addr

will get you something like this ( but more lines )

Code:

2: enp9s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group
3: wlp12s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group

but they might be the old style

...

what does /etc/resolv.conf look liek now that resovconf has been removed?

is it now
/etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf

what are the contents?