[SOLVED] Wireless DNS issue

t0m5k1 · 2017-11-11 10:55:38

I am pulling my hair out as this makes no sense to me.
I can connect to the same router using ethernet fine.
As soon as I connect via wifi I get valid ip but no DNS resolution from browsers!

no captive portal as this is a home connection.
no proxy.

This only affects browsers.

 t0m5k1  ~  ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: wlp0s29u1u3u4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:50:7f:35:ee:23 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.80/24 brd 192.168.0.255 scope global wlp0s29u1u3u4
       valid_lft forever preferred_lft forever
    inet6 2a02:c7f:121b:8200:66a2:8289:16d4:3399/64 scope global dynamic mngtmpaddr noprefixroute 
       valid_lft 3495sec preferred_lft 3495sec
    inet6 fd80:b4ab:cb3c:0:91b2:e532:f5dd:9f2/64 scope global mngtmpaddr noprefixroute 
       valid_lft forever preferred_lft forever
    inet6 fe80::250:7fff:fe35:ee23/64 scope link 
       valid_lft forever preferred_lft forever

 t0m5k1  ~  ip ro
default via 192.168.0.1 dev wlp0s29u1u3u4 src 192.168.0.80 metric 303 
192.168.0.0/24 dev wlp0s29u1u3u4 proto kernel scope link src 192.168.0.80 metric 303 

 t0m5k1  ~  ping bbc.co.uk
ping: bbc.co.uk: Name or service not known

I have no idea what is controlling the nameservers browsers use :

 t0m5k1  ~  resolvconf -l
# resolv.conf from wlp0s29u1u3u4.dhcp
# Generated by dhcpcd from wlp0s29u1u3u4.dhcp
domain Home
search Home
nameserver 192.168.0.1

# resolv.conf from wlp0s29u1u3u4.dhcp6
# Generated by dhcpcd from wlp0s29u1u3u4.dhcp6
nameserver fd80:b4ab:cb3c:0:9221:6ff:fe92:2ed4

# resolv.conf from wlp0s29u1u3u4.ra
# Generated by dhcpcd from wlp0s29u1u3u4.ra
nameserver fd80:b4ab:cb3c:0:9221:6ff:fe92:2ed4

 t0m5k1  ~  dig bbc.co.uk      

; <<>> DiG 9.11.2 <<>> bbc.co.uk
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 35750
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;bbc.co.uk.			IN	A

;; ANSWER SECTION:
bbc.co.uk.		274	IN	A	212.58.246.79
bbc.co.uk.		274	IN	A	212.58.244.22
bbc.co.uk.		274	IN	A	212.58.246.78
bbc.co.uk.		274	IN	A	212.58.244.23

;; Query time: 40 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sat Nov 11 09:27:25 GMT 2017
;; MSG SIZE  rcvd: 102

 t0m5k1  ~  cat /etc/resolv.conf
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients directly to
# all known DNS servers.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver 8.8.8.8
nameserver 8.8.4.4
nameserver 2001:4860:4860::8888
nameserver 2001:4860:4860::8844

As you can see from above resolvconf shows default DNS from DHCP but /etc/resolv.conf is being configured by systemd !!!

So as a test I drop wifi and reconnect ethernet then disable and stopped systemd-resolved, this resulted in no DNS resolution so I then thought logically If I now create and populate resolv.conf all should be grand:

 t0m5k1  ~  cat /etc/resolv.conf
nameserver 8.8.8.8
nameserver 8.8.4.4
#nameserver 2001:4860:4860::8888
#nameserver 2001:4860:4860::8844

but no:

 t0m5k1  ~  ping bbc.co.uk
ping: bbc.co.uk: Name or service not known

 t0m5k1  ~  ip ro                                                                                                                                                                                2 
default via 192.168.0.1 dev enp0s25 proto static 
192.168.0.0/24 dev enp0s25 proto kernel scope link src 192.168.0.14 

 t0m5k1  ~  dig bbc.co.uk             

; <<>> DiG 9.11.2 <<>> bbc.co.uk
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 16052
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;bbc.co.uk.			IN	A

;; ANSWER SECTION:
bbc.co.uk.		54	IN	A	212.58.244.22
bbc.co.uk.		54	IN	A	212.58.246.79
bbc.co.uk.		54	IN	A	212.58.244.23
bbc.co.uk.		54	IN	A	212.58.246.78

;; Query time: 28 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sat Nov 11 10:32:01 GMT 2017
;; MSG SIZE  rcvd: 102

 t0m5k1  ~  nslookup bbc.co.uk
Server:		8.8.8.8
Address:	8.8.8.8#53

Non-authoritative answer:
Name:	bbc.co.uk
Address: 212.58.246.79
Name:	bbc.co.uk
Address: 212.58.246.78
Name:	bbc.co.uk
Address: 212.58.244.22
Name:	bbc.co.uk
Address: 212.58.244.23
Name:	bbc.co.uk
Address: 2001:41c1:400c::bbc:1
Name:	bbc.co.uk
Address: 2001:41c1:4008::bbc:2
Name:	bbc.co.uk
Address: 2001:41c1:4008::bbc:4
Name:	bbc.co.uk
Address: 2001:41c1:4008::bbc:1
Name:	bbc.co.uk
Address: 2001:41c1:400c::bbc:3
Name:	bbc.co.uk
Address: 2001:41c1:400c::bbc:2
Name:	bbc.co.uk
Address: 2001:41c1:4008::bbc:3
Name:	bbc.co.uk
Address: 2001:41c1:400c::bbc:4

 t0m5k1  ~  pacu
:: Synchronising package databases...
error: failed retrieving file 'core.db' from arch.mirror.square-r00t.net : Could not resolve host: arch.mirror.square-r00t.net
error: failed retrieving file 'core.db' from arch.mirror.square-r00t.net : Could not resolve host: arch.mirror.square-r00t.net
<snip>
error: failed to update core (download library error)
error: failed retrieving file 'extra.db' from arch.mirror.square-r00t.net : Could not resolve host: arch.mirror.square-r00t.net
error: failed retrieving file 'extra.db' from arch.mirror.square-r00t.net : Could not resolve host: arch.mirror.square-r00t.net
<snip>
error: failed to update extra (download library error)
error: failed retrieving file 'community.db' from arch.mirror.square-r00t.net : Could not resolve host: arch.mirror.square-r00t.net
error: failed retrieving file 'community.db' from arch.mirror.square-r00t.net : Could not resolve host: arch.mirror.square-r00t.net
<snip>
error: failed to update community (download library error)
error: failed retrieving file 'multilib.db' from arch.mirror.square-r00t.net : Could not resolve host: arch.mirror.square-r00t.net
error: failed retrieving file 'multilib.db' from arch.mirror.square-r00t.net : Could not resolve host: arch.mirror.square-r00t.net
<snip>
error: failed to update multilib (download library error)
error: failed to synchronise any databases
error: failed to init transaction (download library error)

First question:
How do you disable systemd-resolved and still be able to get DNS resolution
Second:
Is systemd-resolved part of my WiFi issue with DNS?
Third:
I thought resolvconf was dealing/managing resolv.conf as I have been using netctl to handle my ethernet connection, Am I being forced to use systemd-resolved now?
Forth:
How do I change the lookup order for DNS? I'd like to put mDNS at the end and file as first choice.

Aside from my questions above I have no clue why I cannot resolve DNS when on WiFi, I am using WiCD to connect as it has always served me well when I use a laptop, this is the first time I have had to use WiFi on my desktop and I cannot keep using the ethernet as my office is not cabled and likely will not get cabled but am currently chaining 2 switches to get a cable to the PC and needless to say the wife is livid and the cat now thinks she has a new toy!

If you need more info/logs please ask.

Last edited by t0m5k1 (2017-11-11 11:57:43)

brebs · 2017-11-11 11:31:29

tcpdump will help.

Multiple ipv6 addresses on wlp0s29u1u3u4, indicates a DHCP release problem. Do you need to use ipv6, or is it there just to cause confusion? Could disable ipv6, by adding ipv6.disable=1 to your bootloader.

t0m5k1 · 2017-11-11 11:57:21

brebs wrote:

tcpdump will help.
Multiple ipv6 addresses on wlp0s29u1u3u4, indicates a DHCP release problem. Do you need to use ipv6, or is it there just to cause confusion? Could disable ipv6, by adding ipv6.disable=1 to your bootloader.

By your response I see you do not fully understand IPv6?

This is the actual IPv6 address given to me by my router which is part of the /64 provided me via the ISP (Sky), note "dynamic".

    inet6 2a02:c7f:121b:8200:66a2:8289:16d4:3399/64 scope global dynamic mngtmpaddr noprefixroute 
       valid_lft 3495sec preferred_lft 3495sec

This address is called ULA (Unique Link Address) this is a fail over IP if the one above stops working due to upstream issues and is provided by the stack once networking is confirmed as working.

    inet6 fd80:b4ab:cb3c:0:91b2:e532:f5dd:9f2/64 scope global mngtmpaddr noprefixroute 
       valid_lft forever preferred_lft forever

This address is a true link local address as part of it is based on my mac address: 00:50:7f:35:ee:23 and uses EUI-64, this address is created locally by the stack and is used to obtain the previous 2 addresses.

    inet6 fe80::250:7fff:fe35:ee23/64 scope link

None of the above is an issue and just shows a fully working and fully routed IPv6 network.
----

I have managed to resolve my issue with DNS failing over wifi by creating the following:

/etc/systemd/network/51-static.network

[Match]
Name=wlp0s29u1u3u4
[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1
DNS=8.8.8.8
DNS=8.8.4.4
DNS=2001:4860:4860::8888
DNS=2001:4860:4860::8844
NTP=0.uk.pool.ntp.org
[DHCP]
UseDNS=false
UseNTP=false

Once created I ran:

systemctl restart systemd-networkd.service

and all is working fine

lo1 · 2017-11-11 12:14:08

I was going to state the obvious about ipv6 but you worked that out on your own, all good!
I was thinking that the problem was a missing ipv6 route pointing at your access point/router or whatever, since i'm seeing only ipv4 in your routing table and i'm not sure this is how it should be.
I was hoping to sort that out, however, if you're ok with that workaround, stick with it! Please would you mind updating this thread if you find something new?

t0m5k1 · 2017-11-11 12:20:07

Hi Io1,

here is the IPv6 routing:

 t0m5k1  ~  ip -6 ro                                                                                                                                                                             1 
2a02:c7f:121b:8200::/64 dev wlp0s29u1u3u4 proto ra metric 1024 pref medium
fd80:b4ab:cb3c::/64 dev wlp0s29u1u3u4 proto ra metric 1024 pref medium
fe80::/64 dev wlp0s29u1u3u4 proto kernel metric 256 pref medium
default via fe80::9221:6ff:fe92:2ed4 dev wlp0s29u1u3u4 proto ra metric 1024 pref medium

Yea I am not to happy with the workaround but I think/guess it is because systemd for some reason was not aware of the wifi link and so giving it a static config seems to have worked.
I am looking into this further and will update this post with finding but I get the feeling I may need to have systemd handle the interface as a whole including connecting to the AP, not the best but at least it works.

ewaller · 2017-11-11 16:05:40

Are you using systemd-network to control your NICs?

Arch Linux

#1 2017-11-11 10:55:38

[SOLVED] Wireless DNS issue

#2 2017-11-11 11:31:29

Re: [SOLVED] Wireless DNS issue

#3 2017-11-11 11:57:21

Re: [SOLVED] Wireless DNS issue

#4 2017-11-11 12:14:08

Re: [SOLVED] Wireless DNS issue

#5 2017-11-11 12:20:07

Re: [SOLVED] Wireless DNS issue

#6 2017-11-11 16:05:40

Re: [SOLVED] Wireless DNS issue

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