NetworkManager doesn't do DNS resolving [solved]

cyberpatrol · Last edited by cyberpatrol on Tue Aug 13, 2013 4:32 am; edited 1 time in total

I'm trying to use NetworkManager. It finds my ethernet card (eth0) and seems to establish a wired connection. It also overwrites /etc/resolv.conf correctly. But domain names aren't resolved.

When NetworkManager is started at boot time I get this message:

666threesixes666 · Posted: Mon Aug 12, 2013 11:19 pm Post subject:

my system shows

mkultra@mksrv [ ~ ]$ cat /etc/resolv.conf
nameserver 8.8.4.4

can you ping 8.8.8.8?? i set static ip and static dns on my setup....

cyberpatrol · Posted: Mon Aug 12, 2013 11:40 pm Post subject:

I haven't tried it, yet, but I doubt that I want to tell Google every website I visit.

My ISP's own DNS server is working correctly since I don't have a problem with DNS resolving when using /etc/init.d/net.eth0 to establish a network connection. And NetworkManager writes the same DNS IPs into /etc/resolv.conf as /etc/init.d/net.eth0 does, just with a different comment.

666threesixes666 · Posted: Tue Aug 13, 2013 12:04 am Post subject:

comment the report of cat /etc/resolv.conf with x.x.x.x or 8.8.8.8 instead of your real dns. don't worry ill spam their data hoard with 90,000 brazzers and gentoo hits for you. maybe set 8.8.8.8 for testing & reporting only....

Jaglover · Posted: Tue Aug 13, 2013 12:08 am Post subject:

I'd say look at ifconfig -a output. Is your eth0 getting an IP address?
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cyberpatrol · Posted: Tue Aug 13, 2013 12:19 am Post subject:

Adding 8.8.8.8 to resolv.conf doesn't help as expected.
ifconfig -a as well as nm-applet show an IP address given by my ISP. So the internet connection is established, just no DNS resolving.

Btw., I found out that `host <IP address>` doesn't work either with NetworkManager.

Jaglover · Posted: Tue Aug 13, 2013 12:29 am Post subject:

Try dig @<yourdnsyouaretesting> <somedomain>, will it resolve or give you an error? For instance, dig @8.8.8.8 www.google.gom
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cyberpatrol · Posted: Tue Aug 13, 2013 12:45 am Post subject:

dig gives me that output:

Jaglover · Posted: Tue Aug 13, 2013 12:53 am Post subject:

Do you have any firewall in action blocking port 53?
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cyberpatrol · Posted: Tue Aug 13, 2013 1:22 am Post subject:

Port 53 is open for UDP and blocked for TCP. If it was blocked, DNS resolving wouldn't work with net.eth0 either.

666threesixes666 · Posted: Tue Aug 13, 2013 1:25 am Post subject:

"don't have a problem with DNS resolving when using /etc/init.d/net.eth0" is what confuses me with the dig results....

cyberpatrol · Posted: Tue Aug 13, 2013 1:46 am Post subject:

Btw., this is the dig output with net.eth0:

666threesixes666 · Posted: Tue Aug 13, 2013 1:52 am Post subject:

so then

Jaglover · Posted: Tue Aug 13, 2013 2:03 am Post subject:

Just for testing I'd shut down that firewall and see if DNS queries get thru.
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cyberpatrol · Posted: Tue Aug 13, 2013 2:24 am Post subject:

@666threesixes666: Yes. No. I'm not starting dhcpcd manually. It get's started automatically by net.eth0 and NetworkManager.
@Jaglover: No need for shutting down the firewall, it's iptables/netfilter anyway. So I just could open it completely, but since it's only port 53, which is open, this can't be the reason.

Jaglover · Posted: Tue Aug 13, 2013 2:31 am Post subject:

Right, that's what I meant, open it completely (same as shut it down) and see if the problem goes away.
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cyberpatrol · Posted: Tue Aug 13, 2013 2:45 am Post subject:

That wouldn't change anything since DNS is done over port 53, and this port is already open. Otherwise net.eth0 wouldn't work. It's pretty unlikely that this is a firewall issue.

Jaglover · Posted: Tue Aug 13, 2013 2:53 am Post subject:

This is basic troubleshooting. You shut down the firewall to see if it is misconfigured. There are services that open an secondary port (as FTP), there are services that use TCP when you don't expect it. I'm trying to help you, eliminate the firewall and see if the problem persists. BTW, don't pay much attention to sixes, she is mostly misfiring.
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666threesixes666 · Posted: Tue Aug 13, 2013 2:55 am Post subject:

id go with what jags saying. rule out the firewall completely. 1 test, 20 seconds...

imaginasys · Posted: Tue Aug 13, 2013 2:57 am Post subject:

can you ping your gateway ? e.g. ping 192.168.1.1 (if you have a router).

do you have a default route to go to the web ? (show output of "route").

I'd suspect incorrect routing.

Regards,
BT :mrgreen:

cyberpatrol · Posted: Tue Aug 13, 2013 4:30 am Post subject:

I must apologize for the noise and thank you all for your help.

Well, opening the firewall helped indeed, but not the way you meant it. It turned out that I had a simple, and admittedly stupid, syntax error in my firewall script that I recently editied for NetworkManager, and didn't use directly with /etc/init.d/net.eth0, since /etc/init.d/iptables just loads a previously saved ruleset.

I just used some wrong braces for setting a variable with either a parameter or a default value: VAR=$(1:-default) instead of VAR=${1:-default}.

So, problem solved.

imaginasys · Posted: Tue Aug 13, 2013 1:24 pm Post subject:

OK! It happens!

Have fun with Gentoo!

cyberpatrol · Posted: Tue Aug 13, 2013 2:20 pm Post subject:

Thanks. I'll definitely will have fun with Gentoo, since I had it already for 5 or 6 years and I'm back after about 5 years of using Arch Linux.