[SOLVED] PC doesn't see DNSes

just-a-guest · 02-04-2015, 11:20 AM

DNS no more works for me. My NetworkManager getting ip addresses via dhcp, and everything seems fine, but when I am trying to ping anything by name, I am getting an error like "unknown host google.com".
I tried to setup then everything via "/etc/network/interfaces", and sometimes it works (at least my PC gets the IP of a provider server to login via l2tp), but just after that the problem appears again.
Below is the end of the "syslog" of the last time I tried to reconnect with NetworkManager, everything seems fine to me:

Code:

Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Auto-activating connection 'Проводное соединение 2'.
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) starting connection 'Проводное соединение 2'
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> (eth0): device state change: disconnected -> prepare (reason 'none') [30 40 0]
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> NetworkManager state is now CONNECTING
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 1 of 5 (Device Prepare) scheduled...
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 1 of 5 (Device Prepare) started...
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) scheduled...
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 1 of 5 (Device Prepare) complete.
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) starting...
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> (eth0): device state change: prepare -> config (reason 'none') [40 50 0]
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) successful.
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 3 of 5 (IP Configure Start) scheduled.
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) complete.
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 3 of 5 (IP Configure Start) started...
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> (eth0): device state change: config -> ip-config (reason 'none') [50 70 0]
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Beginning DHCPv4 transaction (timeout in 45 seconds)
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> dhclient started with pid 5093
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Beginning IP6 addrconf.
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 3 of 5 (IP Configure Start) complete.
Feb  4 19:24:59 constantine-N61Ja dhclient: Internet Systems Consortium DHCP Client 4.2.4
Feb  4 19:24:59 constantine-N61Ja dhclient: Copyright 2004-2012 Internet Systems Consortium.
Feb  4 19:24:59 constantine-N61Ja dhclient: All rights reserved.
Feb  4 19:24:59 constantine-N61Ja dhclient: For info, please visit https://www.isc.org/software/dhcp/
Feb  4 19:24:59 constantine-N61Ja dhclient:
Feb  4 19:24:59 constantine-N61Ja dhclient: parse_option_param: Bad format a
Feb  4 19:24:59 constantine-N61Ja NetworkManager[1115]: <info> (eth0): DHCPv4 state changed nbi -> preinit
Feb  4 19:24:59 constantine-N61Ja dhclient: parse_option_param: Bad format a
Feb  4 19:24:59 constantine-N61Ja dhclient: Listening on LPF/eth0/ae:bb:cb:32:2f:c3
Feb  4 19:24:59 constantine-N61Ja dhclient: Sending on   LPF/eth0/ae:bb:cb:32:2f:c3
Feb  4 19:24:59 constantine-N61Ja dhclient: Sending on   Socket/fallback
Feb  4 19:24:59 constantine-N61Ja dhclient: DHCPREQUEST of 10.20.235.17 on eth0 to 255.255.255.255 port 67 (xid=0x6a2667c1)
Feb  4 19:25:00 constantine-N61Ja avahi-daemon[1083]: Joining mDNS multicast group on interface eth0.IPv6 with address fe80::acbb:cbff:fe32:2fc3.
Feb  4 19:25:00 constantine-N61Ja avahi-daemon[1083]: New relevant interface eth0.IPv6 for mDNS.
Feb  4 19:25:00 constantine-N61Ja avahi-daemon[1083]: Registering new address record for fe80::acbb:cbff:fe32:2fc3 on eth0.*.
Feb  4 19:25:02 constantine-N61Ja dhclient: DHCPREQUEST of 10.20.235.17 on eth0 to 255.255.255.255 port 67 (xid=0x6a2667c1)
Feb  4 19:25:02 constantine-N61Ja dhclient: DHCPACK of 10.20.235.17 from 10.20.235.1
Feb  4 19:25:02 constantine-N61Ja dhclient: bound to 10.20.235.17 -- renewal in 26734 seconds.
Feb  4 19:25:02 constantine-N61Ja NetworkManager[1115]: <info> (eth0): DHCPv4 state changed preinit -> reboot
Feb  4 19:25:02 constantine-N61Ja NetworkManager[1115]: <info>   address 10.20.235.17
Feb  4 19:25:02 constantine-N61Ja NetworkManager[1115]: <info>   prefix 24 (255.255.255.0)
Feb  4 19:25:02 constantine-N61Ja NetworkManager[1115]: <info>   classless static route 10.0.0.0/8 gw 10.20.235.1
Feb  4 19:25:02 constantine-N61Ja NetworkManager[1115]: <info>   classless static route 91.207.136.0/24 gw 10.20.235.1
Feb  4 19:25:02 constantine-N61Ja NetworkManager[1115]: <info>   classless static route 37.18.152.0/24 gw 10.20.235.1
Feb  4 19:25:02 constantine-N61Ja NetworkManager[1115]: <info>   gateway 10.20.235.1
Feb  4 19:25:02 constantine-N61Ja NetworkManager[1115]: <info>   nameserver '91.207.136.55'
Feb  4 19:25:02 constantine-N61Ja NetworkManager[1115]: <info>   nameserver '91.207.136.36'
Feb  4 19:25:02 constantine-N61Ja NetworkManager[1115]: <info>   domain name 'ooonet.ru'
Feb  4 19:25:02 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 5 of 5 (IPv4 Configure Commit) scheduled...
Feb  4 19:25:02 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 5 of 5 (IPv4 Commit) started...
Feb  4 19:25:02 constantine-N61Ja avahi-daemon[1083]: Joining mDNS multicast group on interface eth0.IPv4 with address 10.20.235.17.
Feb  4 19:25:02 constantine-N61Ja avahi-daemon[1083]: New relevant interface eth0.IPv4 for mDNS.
Feb  4 19:25:02 constantine-N61Ja avahi-daemon[1083]: Registering new address record for 10.20.235.17 on eth0.IPv4.
Feb  4 19:25:03 constantine-N61Ja NetworkManager[1115]: <info> (eth0): device state change: ip-config -> secondaries (reason 'none') [70 90 0]
Feb  4 19:25:03 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) Stage 5 of 5 (IPv4 Commit) complete.
Feb  4 19:25:03 constantine-N61Ja NetworkManager[1115]: <info> (eth0): device state change: secondaries -> activated (reason 'none') [90 100 0]
Feb  4 19:25:03 constantine-N61Ja NetworkManager[1115]: <info> NetworkManager state is now CONNECTED_GLOBAL
Feb  4 19:25:03 constantine-N61Ja NetworkManager[1115]: <info> Policy set 'Проводное соединение 2' (eth0) as default for IPv4 routing and DNS.
Feb  4 19:25:03 constantine-N61Ja NetworkManager[1115]: <info> Writing DNS information to /sbin/resolvconf
Feb  4 19:25:03 constantine-N61Ja dnsmasq[1259]: setting upstream servers from DBus
Feb  4 19:25:03 constantine-N61Ja dnsmasq[1259]: using nameserver 91.207.136.36#53
Feb  4 19:25:03 constantine-N61Ja dnsmasq[1259]: using nameserver 91.207.136.55#53
Feb  4 19:25:03 constantine-N61Ja NetworkManager[1115]: <info> Activation (eth0) successful, device activated.
Feb  4 19:25:03 constantine-N61Ja dbus[766]: [system] Activating service name='org.freedesktop.nm_dispatcher' (using servicehelper)
Feb  4 19:25:03 constantine-N61Ja dbus[766]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
Feb  4 19:25:03 constantine-N61Ja ntpdate[5158]: Can't find host ntp.ubuntu.com: Name or service not known (-2)
Feb  4 19:25:03 constantine-N61Ja ntpdate[5158]: no servers can be used, exiting

This problem appeared some time ago, but till now it did somehow fixed on itself. But now I can't even connect to internet, I am writing this message from an old notebook - there everything works fine.

So bizzare, I have no even idea where to seek the problem…

Update: okay, perhaps this could be useful: I just managed to fix it again. I just restarted the PC without the cabel (of course, it was in old notebook). After the first reboot just after I saw a desktop I was trown to login screen again — my XServer just failed without a reason, even the «Xorg.0.log» was okay, I guess it was some fail of KDM. Then I rebooted again, and now everything works.

OS: Kubuntu 14.04.1 LTS

veerain · 02-04-2015, 12:14 PM

Just put this line on top of the file /etc/resolv.conf

Code:

nameserver 8.8.8.8

Comment other lines starting with nameserver by putting this at start of line '#'

Now try ping.

just-a-guest · 02-04-2015, 12:53 PM

Quote:

Originally Posted by veerain

Just put this line on top of the file /etc/resolv.conf

Code:

nameserver 8.8.8.8

Comment other lines starting with nameserver by putting this at start of line '#'

Now try ping.

No, this won't work. To use 8.8.8.8 I ought to be connected to the internet. But to connect I ought to have DNS, because my provider uses «ooonet.ru» as the name of l2tp server, instead of its IP.
But anyway, the problem not in the server DNS, but rather somewhere inside my system — because from my old laptop with Xubuntu I didn't had a problem with a network.

TB0ne · 02-04-2015, 01:55 PM

Quote:

Originally Posted by veerain

Just put this line on top of the file /etc/resolv.conf

Code:

nameserver 8.8.8.8

Comment other lines starting with nameserver by putting this at start of line '#' Now try ping.

Please, don't give such advice. Most distros these days overwrite resolv.conf, based on the /etc/sysconfig/network configuration files. So any changes you manually make WILL BE LOST when you reboot.

Quote:

Originally Posted by just-a-guest

No, this won't work. To use 8.8.8.8 I ought to be connected to the internet. But to connect I ought to have DNS, because my provider uses «ooonet.ru» as the name of l2tp server, instead of its IP. But anyway, the problem not in the server DNS, but rather somewhere inside my system — because from my old laptop with Xubuntu I didn't had a problem with a network.

You don't say what version/distro of Linux you're using, but you can still modify your DNS settings to (PERHAPS) sidestep this issue. Look for the /etc/sysconfig/network/config file...if you find it, open it up and look for the NETCONFIG_DNS_STATIC_SERVERS line. Modify it to be:

Code:

NETCONFIG_DNS_STATIC_SERVERS="8.8.8.8 8.8.4.4"

That will FORCE your system to use the public Google DNS servers, regardless of the DHCP address/information it gets handed. Those names should then be written to the resolv.conf file upon boot, and used by any network connections made. It will at least be a diagnostic tool.

just-a-guest · 02-04-2015, 02:50 PM

I didn't understood how could this help, since I won't have an access to Google DNS servers if I refuse a provider's ones. Because to connect to the internet xl2tp daemon ought to get IP address of the «ooonet.ru» provider's server.
Either way, I have no the file «/etc/sysconfig/network/config». Next I tried to grep recursively my «/etc/» dir to find the word «NETCONFIG_DNS_STATIC_SERVERS», but found nothing.

Quote:

You don't say what version/distro of Linux you're using

Sorry, I am happy owner of Kubuntu ^^
I'll add it in my post.

veerain · 02-04-2015, 02:58 PM

Well in that case you get IP Address of 'ooonet.ru' from some other internet connected system. And then put this line in /etc/hosts file.

Code:

x.x.x.x     ooonet.ru

Replace x.x.x.x ooonet.ru with proper ones.

Doc CPU · 02-04-2015, 03:18 PM

Hi there,

Quote:

Originally Posted by just-a-guest

To use 8.8.8.8 I ought to be connected to the internet. But to connect I ought to have DNS, because my provider uses «ooonet.ru» as the name of l2tp server, instead of its IP.

that sounds a bit weird. What do you mean by "l2tp"?

Anyway, usually you get your necessary configuration via DHCP. Apparently, this works in your scenario, and your ISP assigns the nameservers 91.207.136.36 and 91.207.136.55 for you. They should resolve all subsequent host name queries.

But I see there's also dnsmasq running on your system. Are you using it for a certain purpose? Maybe dnsmasq (or a bad configuration) is the culprit. Did you try to disable dnsmasq?

[X] Doc CPU

just-a-guest · 02-04-2015, 10:29 PM

Quote:

Originally Posted by doc cpu

Quote:

Originally Posted by just-a-guest

To use 8.8.8.8 I ought to be connected to the internet. But to connect I ought to have DNS, because my provider uses «ooonet.ru» as the name of l2tp server, instead of its IP.

that sounds a bit weird. What do you mean by "l2tp"?

VPN l2tp is a way of my provider to provide us with Internet.

Quote:

Originally Posted by doc cpu

But I see there's also dnsmasq running on your system. Are you using it for a certain purpose? Maybe dnsmasq (or a bad configuration) is the culprit. Did you try to disable dnsmasq?

No, I don't. I guess I installed it for a reason, but it was long before, and probably the reason now disappeared. Thank you, I have to disable it; I'll write this evening does it helped.

just-a-guest · 02-05-2015, 11:15 AM

Okay, I am launched my PC and an internet still doesn't work. Then I thought to try to ping, and look with «tcpdump -i eth0 | grep 91.207». I pinged «foo.com» to be sure that the address wasn't ever cached. When the ping wrote «unknown host» I didn't saw any message from tcpdump to DNS.
But the weird thing is that when I repeated this with the old laptop where everything works, despite successful ping, I didn't saw an output either.

UPD:
The problem solved → I did «sudo dpkg-reconfigure resolvconf» to recreate the symbolic link «/etc/resolv.conf» — since it was modified by me to follow many tutorials, it wasn't a link. Now it works.