[Bug 1766969] [NEW] DNS cannot be resolved in Hotel Hotspot

[Pete]

Public bug reported:

I was asked to create a new bug for this in
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1727237 as it
seems to be a different issue.

I have installed the nightly image of Kubuntu Bionic from 25th of April.

There systemd is in version 237-3ubuntu10.

When connecting to the wifi hotspot in my hotel (Quality Hotel Augsburg)
I cannot open the hotspot landing page that should give me access to the
WIFI. With Windows and on an Iphone it's working.

For the following distributions I can confirm it not working:
Kubuntu 17.10
Kubuntu 18.04 (nightly image 25th of April 2018)

The logs were taken on 18.04.

Workaround:
sudo systemctl disable systemd-resolved.service
sudo service systemd-resolved stop
sudo rm /etc/resolv.conf
sudo nano /etc/NetworkManager/NetworkManager.conf
  >> add "dns=default" under [main]
sudo service network-manager restart

Then I can connect to the WIFI and I see the login page in Firefox.

To capture some data I did the following:
 - connect to Hotspot
 - enter golem.de

Case 1: Fresh default Kubuntu install
With a default Kubuntu install it does not work. I can connect to the WIFI and get IP and DNS from DHCP but I cannot resolve any hostname. When trying to open the router ip directly in the browser it forwards to hotsplots.de which cannot be resolved.

Case 2: With aforementioned Workaround
I connect to the wifi, I open firefox and the login page shows up (if I havent been connected yet. In the capture I already was able to connect to the hotspot which allows immediately to connect to the webpage)

PS: I'll be in this hotel till Friday 27th if more information are
required.

** Affects: systemd (Ubuntu)
Importance: Undecided
Status: New


** Tags: dns systemd systemd-resolv
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Title:
DNS cannot be resolved in Hotel Hotspot

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[Pete]

Wireshark logs for default conf of Kubuntu and logs with workaround

** Attachment added: "wireshark logs"
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1766969/+attachment/5127251/+files/dnsresolv.7z

** Tags added: dns systemd systemd-resolv

** Description changed:

I was asked to create a new bug for this in
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1727237 as it
seems to be a different issue.

I have installed the nightly image of Kubuntu Bionic from 25th of April.

There systemd is in version 237-3ubuntu10.

+ When connecting to the wifi hotspot in my hotel (Quality Hotel Augsburg)
+ I cannot open the hotspot landing page that should give me access to the
+ WIFI. With Windows and on an Iphone it's working.
+
+ For the following distributions I can confirm it not working:
+ Kubuntu 17.10
+ Kubuntu 18.04 (nightly image 25th of April 2018)
+
+ The logs were taken on 18.04.
+
Workaround:
sudo systemctl disable systemd-resolved.service
sudo service systemd-resolved stop
- sudo rm /etc/resolv.conf
- sudo nano /etc/NetworkManager/NetworkManager.conf
- >> add "dns=default" under [main]
+ sudo rm /etc/resolv.conf
+ sudo nano /etc/NetworkManager/NetworkManager.conf
+   >> add "dns=default" under [main]
sudo service network-manager restart

+ Then I can connect to the WIFI and I see the login page in Firefox.

- Then I can connect to the WIFI and I see the login page in Firefox.
-
- To capture some data I did the following:
- - connect to Hotspot
- - enter golem.de
+ To capture some data I did the following:
+  - connect to Hotspot
+  - enter golem.de

Case 1: Fresh default Kubuntu install
- With a default Kubuntu install it does not work. I can connect to the WIFI and get IP and DNS from DHCP but I cannot resolve any hostname. When trying to open the router ip directly in the browser it forwards to hotsplots.de which cannot be resolved.
+ With a default Kubuntu install it does not work. I can connect to the WIFI and get IP and DNS from DHCP but I cannot resolve any hostname. When trying to open the router ip directly in the browser it forwards to hotsplots.de which cannot be resolved.

Case 2: With aforementioned Workaround
I connect to the wifi, I open firefox and the login page shows up (if I havent been connected yet. In the capture I already was able to connect to the hotspot which allows immediately to connect to the webpage)

** Description changed:

I was asked to create a new bug for this in
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1727237 as it
seems to be a different issue.

I have installed the nightly image of Kubuntu Bionic from 25th of April.

There systemd is in version 237-3ubuntu10.

When connecting to the wifi hotspot in my hotel (Quality Hotel Augsburg)
I cannot open the hotspot landing page that should give me access to the
WIFI. With Windows and on an Iphone it's working.

- For the following distributions I can confirm it not working:
+ For the following distributions I can confirm it not working:
Kubuntu 17.10
Kubuntu 18.04 (nightly image 25th of April 2018)

The logs were taken on 18.04.

Workaround:
sudo systemctl disable systemd-resolved.service
sudo service systemd-resolved stop
sudo rm /etc/resolv.conf
sudo nano /etc/NetworkManager/NetworkManager.conf
  >> add "dns=default" under [main]
sudo service network-manager restart

Then I can connect to the WIFI and I see the login page in Firefox.

To capture some data I did the following:
 - connect to Hotspot
 - enter golem.de

Case 1: Fresh default Kubuntu install
With a default Kubuntu install it does not work. I can connect to the WIFI and get IP and DNS from DHCP but I cannot resolve any hostname. When trying to open the router ip directly in the browser it forwards to hotsplots.de which cannot be resolved.

Case 2: With aforementioned Workaround
I connect to the wifi, I open firefox and the login page shows up (if I havent been connected yet. In the capture I already was able to connect to the hotspot which allows immediately to connect to the webpage)
+
+ PS: I'll be in this hotel till Friday 27th if more information are
+ required.
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Title:
DNS cannot be resolved in Hotel Hotspot

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[Launchpad Bug Tracker]

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: systemd (Ubuntu)
Status: New => Confirmed
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Title:
DNS cannot be resolved in Hotel Hotspot

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[Steve Langasek]

Can confirm that the dns logs indicate that systemd-resolved is not
falling back from UDP+EDNS0 to UDP in response to these NXDOMAIN
answers.

The existing patch only implements this fallback when the portal name
being looked up includes 'secure' as a substring:

+ if (DNS_PACKET_RCODE(p) == DNS_RCODE_NXDOMAIN && t->current_feature_level >= DNS_SERVER_FEATURE_LEVEL_EDNS0) {
+
+ char key_str[DNS_RESOURCE_KEY_STRING_MAX];
+ dns_resource_key_to_string(t->key, key_str, sizeof key_str);
+ if (strstr(key_str, "secure") != NULL) {
+ t->current_feature_level = t->current_feature_level - 1;
+
+ log_warning("Server returned error %s, suspecting DNS violation DVE-2018-0001, retrying transaction with reduced feature level %s.",

The packet capture shows a number of DNS lookups, but not containing the
substring 'secure'; and none that appear to correspond to the captive
portal itself. This may require a different sort of solution than the
previous bug, I'm not sure.
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Title:
DNS cannot be resolved in Hotel Hotspot

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[Dimitri John Ledkov]

I'm now questioning if it is at all sensible to use EDNS by default.

It seems like the fallback should be widened for all NXDOMAIN lookups.

I've validated, that lookups fail, when DNSSEC enabled (however with a
SERVFAIL, rather than NXDOMAIN). Note DNSSEC is not enabled by default.
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Title:
DNS cannot be resolved in Hotel Hotspot

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[Steve Langasek]

The internal resolver of systemd does not properly search the local dns.
Only fqdn's will resolve. This is easily mitigated and does not require
a whole bunch of enabling or disabling of things.

That is unrelated to this bug report.
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Title:
DNS cannot be resolved in Hotel Hotspot

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[Mark Daku]

I have encountered this bug as well.

I have raised it with systemd-resolved.
The internal resolver of systemd does not properly search the local dns. Only fqdn's will resolve. This is easily mitigated and does not require a whole bunch of enabling or disabling of things.

The DHCP process will almost always provide a valid DNS locally and the
DHCP client in systemd does actually create a valid resolve.conf. You
just have to point /etc/resolv.conf to it.

At the time of writing the systemd people refuse to accept that this is
a bug. They continue to refer to it as a documentation issue. I honestly
don't believe they are testing it.

# Just making sure I'm out of the / dir
cd /etc
# resolv.conf is a link to ../run/systemd/resolve/stub-resolv.conf Which directs thing to use the local resolved. So I nuke it.
sudo rm resolve.conf
# Then I go and use the actual resolv.conf that actually works.
sudo ln -s ../run/systemd/resolve/resolv.conf resolv.conf


The above workaround is good. It will allow you to take your laptop onto all different types of networks. It will work correctly. This is for at least systemd version 237 and above. I haven't checked to see if 236 has the proper file generated or not.
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Title:
DNS cannot be resolved in Hotel Hotspot

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[Mark Schroeder]

I have the latest systemd recommended by #1727237, and this issue still
occurs at Starbucks as well. The Starbucks WIFI defect is #1767900
which appears to be a duplicate of this one.

ii systemd 237-3ubuntu10
amd64 system and service manager

I'm in a Starbucks now. #1727237 (the systemd above) does not fix my
issue. aruba.odyssys.net is still not resolved using the stub-
resolv.conf file (linked from /etc/resolv.conf).

cd /etc
sudo /bin/rm resolv.conf
sudo /bin/ln -s ../run/systemd/resolve/resolv.conf resolv.conf

Using the original resolv.conf however, as per the changes above, does
work. I did not make any changes to /etc/hosts. The real resolv.conf
above contains the google nameservers and is sufficient to resolve
aruba.odyssys.net.

nameserver 8.8.8.8
nameserver 8.8.4.4
search home
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Title:
DNS cannot be resolved in Hotel Hotspot

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[Dimitri John Ledkov]

** Changed in: systemd (Ubuntu Cosmic)
Status: Confirmed => Fix Committed
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Title:
DNS cannot be resolved in Public / Hotel / Starbucks WiFi Hotspot

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[Dimitri John Ledkov]

** Also affects: systemd (Ubuntu Artful)
Importance: Undecided
Status: New

** Also affects: systemd (Ubuntu Cosmic)
Importance: Undecided
Status: Confirmed

** Also affects: systemd (Ubuntu Bionic)
Importance: Undecided
Status: New
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Title:
DNS cannot be resolved in Public / Hotel / Starbucks WiFi Hotspot

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[mike stewart]

This seems to affect many public Wifi Hotspots. A very common example is
the new setup by Starbucks/Google (usually seen as **Google Starbucks
Wifi**) in the US by (Tech behind it is https://globalreachtech.com/
with their http://odyssys.net/).

Under Ubuntu 16.04, Windows, Android, Mac OS, or iPhone, a WiFi guest
user can connect without problem. However, since upgrading to Ubuntu
18.04, I've encountered this in at least three separate Starbucks stores
in Southern California.


## WORKAROUND ##

An easier workaround, with fewer system modifications than the original
bug report is to use `ip route` to determine the IP address of the host
router, then add the hostname with that adress to `/etc/hosts`


Step by step details can be found here: https://askubuntu.com/a/1027605/139249
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DNS cannot be resolved in Public / Hotel / Starbucks WiFi Hotspot

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[mike stewart]

** Summary changed:

- DNS cannot be resolved in Hotel Hotspot
+ DNS cannot be resolved in Public / Hotel / Starbucks WiFi Hotspot
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[Steve Langasek]

I can reproduce @earth2mark-eeepc's findings at another Starbucks.
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