Hello,
On Do, 2019-10-31 at 17:38 +0000, Michael Tremer wrote:
Hi,
On 31 Oct 2019, at 16:29, ummeegge ummeegge@ipfire.org wrote:
Hi all,
On Do, 2019-10-31 at 15:13 +0000, Michael Tremer wrote:
Hello,
I just had a conversation with Arne about our DNS setup right now.
We see are couple of problems which have been ongoing for a long time and we have worked out how we are going to solve them. In this email, I would like to involve everybody else in this conversation and hopefully you people have some ideas how to make this even better!
First of all we have some unreleased features:
Safe Search is implemented, but there is no UI to enable it
We can force unbound to only use TCP which circumvents some
problems with corrupted UDP packets. No UI either.
Then we have our long test script which we have tweaked a lot but it is largely a black box for users and therefore does not work. I am strongly believing in that we need to get rid of it. Entirely.
However, there is some other objectives that we would like to realise at the same time:
Being able to configure more than two name servers
Lay a foundation for DNS over TLS
Allow for users who really really really do not want any
security to disable DNSSEC. For some reason they believe that the security is causing their DNS problems when it is usually not.
- Adopt some recommended configuration from DNS flag day (EDNS
buffer size = 1232)
- Remove the many places where users can configure DNS servers
depending on how they connect to the Internet (Static, DHCP, PPP, …)
So the solution that we have come up with is as follows:
- Remove automatic fallback to recursor mode. This seems to
confuse people and they think that this is something bad. No idea why. People.
Remove the test script.
DNS servers can be configured on a new dns.cgi by the user. It
will be a list which can hold as many DNS servers as you like.
- DNS servers will be stored in a CSV file and when we receive
some from the ISP (via DHCP or PPP) we will add them and flag them as coming from the ISP
- There will be a switch to enable/disable using the ISP DNS
servers
- We will remove the UI from the setup. That will result in
people who use static not being able to configure any DNS servers during setup. We will compensate for that by changing to recursor mode when no DNS servers are known. That is the only thing we can do here since we do not want to ship a default list of DNS servers.
This will simplify the whole DNS problem by only providing one UI for everyone regardless of how they connect to the Internet. The user has a lot more influence on what is being configured so there should be less of a chance of useless DNS servers there.
Does anybody have any objections or additions to this?
Since this is going to be a huge project I am looking for people who would like to join in and contribute their time :) Hands up!
Best, -Michael
Regarding DNS-over-TLS but also the CGI we (me and a smaller testing group ~7 are known) have updated the DoT project until today and all is up and running since a year now. The CGI is based on the dnsforward.cgi and therefor pretty much the same.
And why is this not being put forward to be upstreamed at some time?
Pushed it some time ago to Git we had at that time also a bigger conversation in the mailinglist which included also similar points then here. Have asked there also for help to integrate all DNS related sections into one CGI but got at that time whether testers nor further help in any shape or form. Via forum was a much better resonance on testing side, therefor all has been done there until today.
As far as I know the project stalled. Why?
Made all updates especially for unbound init and en.pl but for DoT only with several already mentioned tests also until today. It makes no sense to go there further since a lot of work might be again made but useless since another way of implementation might be demanded and the complete integration of all DNS sections into one WUI is from my side at first not possible since i can not test it and at a second simply not possible according to my knowledge.
What did we tried there:
- We experienced with 'tcp_fastopen' which doesn´t work cause an
OpenSSL problem --> https://github.com/openssl/openssl/issues/4783 .
Is this on the client or server side?
I guess this is not critical at all and we have to wait until upstream fixes this.
Both should be enabled by default in IPFire.
have seen this here --> https://www.mail-archive.com/unbound-users@nlnetlabs.nl/msg00523.html in unbound mailinglist, there it looks like OpenSSL does not have a function to perform TFO on Linux in general...
- The current configuration uses 'qname-minimisation strict' since
february 2019 with no problems (or which i know of from the reports).
That is another thing we wanted to make configurable by the user.
Good idea.
There were concerns that this will cause problems in some environments.
Haven´t heard about problems in the forum topic but there where only a couple of testers (nevertheless > 10000 views with may some more quiet testers...)
- DNSSec runs if possible which is possible on 80% (10 configured
DoT´s whereby ~ 2 have a problem with DNSsec).
Those servers simply won’t be usable then.
Yes, even the certificate validation (crypto) worked there but nevertheless insecure.
- Have checked ESNI which was at a first glance possible but only
with an enabled DoH in Firefox whereby all superficial tests (Cloudflair mainly :( ) showed it as enabled but tshark did not shared that opinion. In my opinion not usable at this time but there is also movement in there...
I do not care about DNS over HTTPS. It is a flawed technology pushed by a large corporation.
Me too. Am also not a fan of the whole Cloudflair hype even they are meanwhile part of the Firefox configuration and Mozilla wanted to have the whole DoH thing per default on (beneath some other cruelties).
We have no benefit over DNS over TLS. Just more overhead.
ESNI is there a topic which is important but it should really find others ways than via DoH in my opinion.
- Have wrote a couple of scripts to check for usablility of the
configuration and we ended up with a work around which displays DNS- over-TLS in index.cgi with color codes (red=off ; orange = no DNSSec ; green = all is good) which looks like this --> https://people.ipfire.org/~ummeegge/screenshoots/DoT_indexCGI.png
What I talked about with Arne today was to remove the section on index.cgi.
We thought it will be crowded and the current DNS configuration which is actually in place can be viewed on the new DNS CGI. So this could go away.
I think this is a good idea. All that can also be made via an own CGI.
Telling from the screenshot we were right about the crowdedness.
:D . By the usage of 10+ addresses, yes it is...
What are the colours for?
red = The certificate is not trustworthy orange = Certificate is trustworthy but DNSsec do not works green = All is good
<-- am not happy with this but it works and might be enough for testings. So far to DoT.
I would need help in structuring the CGI for all the mentioned opportunities by starting it conceptionally togehter (not only talking or writing but in concrete code since i stuck with some stuff) and can then hold my hand up a little (that nobody see´s it ;) to help further. May it is not that far away to integrate all that in the meanwhile existing environment ?!
Where is your code? That would be a good start.
Have pushed now all i have --> https://git.ipfire.org/?p=people/ummeegge/ipfire-2.x.git;a=commit;h=d62c9a43...
Some thoughts from here.
Best,
Erik