DNS with dhcpcd and WiFi

ExecutorElassus · Posted: Thu Oct 12, 2017 7:20 pm Post subject: DNS with dhcpcd and WiFi

I have a laptop running gentoo, and it consistently has issues with WiFi. I can add access points by editing /etc/wpa_supplicant/wpa_supplicant.conf, and it connects fine. Ping with an IP address works fine, but ping with a URL returns nothing at all, and I get errors about "unable to resolve address" issues from the browser.

/etc/resolv.conf has four IP addresses manually entered (two each for OpenDNS and google), plus one added by the router from dhcpcd.

How can I debug why DNS lookups aren't working, and how can I fix it?

Cheers,

EE

UberLord · Posted: Thu Oct 12, 2017 7:48 pm Post subject:

libc (the main reader of /etc/resolv.conf) is normally limited to 3 resolvers max - so the last two won't be used.

But you can test DNS by use of the dig command

ExecutorElassus · Posted: Fri Oct 13, 2017 4:07 am Post subject:

What package provides dig? I don't seem to have it installed.

Also, the four nameservers I have listed are apparently added to resolv.conf, as deleting them gets overwritten on reboot. Where else might I have them listed?

Cheers,

EE
Update: I take it back. It's not just DNS: commenting out two nameservers, I could resolve addresses. But then I got "destination host unreachable" errors. Even checking with ping, it can't get past the router. So wifi connects to the router, but cant get past it. How can I debug this and fix it?

bbgermany · Posted: Fri Oct 13, 2017 5:52 am Post subject:

Hi,

did you set a default route? Please check with

ExecutorElassus · Posted: Fri Oct 13, 2017 3:04 pm Post subject:

'netstat -rn' returns:

bbgermany · Posted: Fri Oct 13, 2017 4:07 pm Post subject:

Hi,

there is your issue; two default gateways and no metric. Your system doesnt know which way it should go and where the packages return.

greets, bb
_________________
Desktop: Ryzen 5 5600G, 32GB, 2TB, RX7600
Notebook: Dell XPS 13 9370, 16GB, 1TB
Server #1: Ryzen 5 Pro 4650G, 64GB, 16.5TB
Server #2: Ryzen 4800H, 32GB, 22TB

UberLord · Posted: Sat Oct 14, 2017 9:28 am Post subject:

netstat won't show route metric - you need iproute2 for that

ExecutorElassus · Posted: Sun Oct 15, 2017 10:56 am Post subject:

'ip r' returns:

szatox · Advocate Joined: 27 Aug 2013 Posts: 3137

Does it start working either after removing this route manually:

ExecutorElassus · Posted: Sun Oct 15, 2017 5:39 pm Post subject:

I didn't get better results restarting dhcpcd; how do I remove that route manually?

Cheers,

EE

szatox · Advocate Joined: 27 Aug 2013 Posts: 3137

ExecutorElassus · Posted: Mon Oct 16, 2017 9:15 am Post subject:

no, restarting dhcpcd did not remove that route. However, removing it manually did enable me to get a working internet, hurrah!

Now: how do I ensure that the routes associated with enp4s0 aren't active when I'm not connected to an ethernet cable, so that only the routes associated with wlp3s0 are used?

Thanks for the help! It's almost there!

EE

nokilli · Apprentice Joined: 25 Feb 2004 Posts: 196

Not saying this is right, but I've always been manually starting and stopping these things.