[arch-general] BIND, systemd-resolved, and nscd
Hello Arch General, I hope this is the right mailing list; I'm a new subscriber. After a recent upgrade I found that DNS broke in two different ways on my computer, 1. BIND enabled DNSSEC by default, causing hostname resolution to stop working (for some reason my home wireless router broke the "trust chain", which I know nothing about) https://kb.isc.org/article/AA-01636/81/BIND-9.13.2-Release-Notes.html The default setting for dnssec-validation is now auto, which activates DNSSEC validation using the IANA root key. I had to add "dnssec-validation yes;" to /etc/named.conf. I have a forwarding BIND configuration so that Spamassassin's DNSBL queries can be handled specially. 2. There is a bug relating to systemd-resolved and nscd. It is also related to a decision made by systemd-resolved maintainers to never use DNS to resolve single-label hostnames: https://github.com/systemd/systemd/issues/2514 https://sourceware.org/bugzilla/show_bug.cgi?id=23546 This was very confusing to me because I had assumed that my computers were still using DNS to find each other via my router, as I had not changed anything related to that configuration. While trying to debug these problems, I remember checking the "Arch Linux - News" page (https://www.archlinux.org/news/) but I didn't find anything relevant there. I wonder it makes sense to expect that changes which break hostname resolution on home networks, or which may require reconfiguration on common setups to maintain existing functionality, should be announced on this page. I would be in favor of that but I don't know how I would phrase the announcement. For what it's worth, I was not able to find help with these problems on #archlinux or the BBS or superuser.com. Any thoughts? Best wishes, Frederick
I had to add "dnssec-validation yes;" to /etc/named.conf. I have a
Are you sure you didn't want these values? dnssec-enable no; dnssec-validation no; Matt Pallissard
On Thu, Sep 13, 2018 at 06:49:45AM -0700, Pallissard, Matthew wrote:
I had to add "dnssec-validation yes;" to /etc/named.conf. I have a
Are you sure you didn't want these values?
dnssec-enable no; dnssec-validation no;
Well, prior to the recent BIND releease, the default had been "yes" - which means "no" for me. I just wanted to make it behave the same way as it had before. I don't know if there's a difference between that and the options you suggested: ftp://ftp.isc.org/isc/bind9/cur/9.10/doc/arm/Bv9ARM.ch06.html#Configuration_File_Grammar If set to auto, DNSSEC validation is enabled, and a default trust anchor for the DNS root zone is used. If set to yes, DNSSEC validation is enabled, but a trust anchor must be manually configured using a trusted-keys or managed-keys statement. The default is yes. Here's my SU question BTW: https://superuser.com/questions/1349213/how-to-debug-local-named-with-broken... Matthew, do you know more about this stuff or were you just as confused as I was by the "yes means no" syntax? I didn't necessarily want to get into that in this thread, although it could potentially be something for us to complain to the BIND maintainers about. (viz., people thinking they had enabled dnssec-validation when in fact they hadn't) Frederick
On 2018-09-13T12:31:28, frederik@ofb.net wrote:
On Thu, Sep 13, 2018 at 06:49:45AM -0700, Pallissard, Matthew wrote:
I had to add "dnssec-validation yes;" to /etc/named.conf. I have a
Are you sure you didn't want these values?
dnssec-enable no; dnssec-validation no;
Well, prior to the recent BIND releease, the default had been "yes" - which means "no" for me. I just wanted to make it behave the same way as it had before. I don't know if there's a difference between that and the options you suggested:
ftp://ftp.isc.org/isc/bind9/cur/9.10/doc/arm/Bv9ARM.ch06.html#Configuration_File_Grammar
If set to auto, DNSSEC validation is enabled, and a default trust anchor for the DNS root zone is used. If set to yes, DNSSEC validation is enabled, but a trust anchor must be manually configured using a trusted-keys or managed-keys statement. The default is yes.
Here's my SU question BTW:
https://superuser.com/questions/1349213/how-to-debug-local-named-with-broken...
Matthew, do you know more about this stuff or were you just as confused as I was by the "yes means no" syntax? I didn't necessarily want to get into that in this thread, although it could potentially be something for us to complain to the BIND maintainers about. (viz., people thinking they had enabled dnssec-validation when in fact they hadn't)
Frederick
A few things. 1. Google's public DNS servers are DNSSEC validating forwarders, your router evidently is not. 2. I'm not sure what you mean by the yes-means-no syntax. The URL that you provided seems pretty cut and dry.
dnssec-enable yes; # returns dnssec resource records dnssec-enable nol # does not, validation cannot be performed dnssec-validation no; #does not validate dnssec-validation yes; #does validate (requires a trusted-keys or managed-keys statement, which you DO NOT have in your example) dnssec-validation autol #does validate (uses trusted/manged-keys blocks or the trust anchor compiled into named)
TL;DR If you want to 'make it behave the same way as it had before', it sounds like you need to disable DNSSEC validation. If you want to make it honour DNSSEC set dnssec-validation to 'auto' or 'yes' with the related keys statement. Matt Pallissard
> > Well, prior to the recent BIND releease, the default had been "yes" - > > which means "no" for me. > ... > 2. I'm not sure what you mean by the yes-means-no syntax. The URL that you provided seems pretty cut and dry. > ... > > dnssec-validation yes; #does validate (requires a trusted-keys or managed-keys statement, which you DO NOT have in your example) I think you just answered your own question. Except perhaps that the word "requires" is a bit misleading, because when you don't have that statement then 'named' still starts up and responds to queries, it just doesn't do DNSSEC validation. So 'named' itself does not "require" it. Your first email wondered if I didn't want "no" instead of "yes" and I was explaining that they are the same for my configuration, which is based on the default named.conf that ships with bind, which doesn't have a trusted-keys or managed-keys statement. In other words, they are also the same for the default configuration. As I explained, "yes" was the default validation setting and I was trying to restore the old behavior, which doesn't do validation. I was wondering why you had asked this question, if you had some kind of expert knowledge that I didn't have - but it looks like we are learning about this together, since you are referring to the URL I provided. The purpose of my original post was to ask whether this sort of change in the defaults of an important package belongs in the Arch news page (https://www.archlinux.org/news/), but I haven't received an answer yet. I'm open to advice on question-asking or if this is the right forum or whatever. Thanks, Frederick
On 2018-09-19T11:22:16, frederik@ofb.net wrote: > > > Well, prior to the recent BIND releease, the default had been "yes" - > > > which means "no" for me. > > ... > > 2. I'm not sure what you mean by the yes-means-no syntax. The URL that you provided seems pretty cut and dry. > > ... > > > dnssec-validation yes; #does validate (requires a trusted-keys or managed-keys statement, which you DO NOT have in your example) > > I think you just answered your own question. Except perhaps that the > word "requires" is a bit misleading, because when you don't have that > statement then 'named' still starts up and responds to queries, it > just doesn't do DNSSEC validation. So 'named' itself does not > "require" it. Fair point, maybe raise that on the ISC list. > Your first email wondered if I didn't want "no" instead of "yes" and I > was explaining that they are the same for my configuration, which is > based on the default named.conf that ships with bind, which doesn't > have a trusted-keys or managed-keys statement. In other words, they > are also the same for the default configuration. As I explained, "yes" > was the default validation setting and I was trying to restore the old > behavior, which doesn't do validation. I was wondering why you had > asked this question, if you had some kind of expert knowledge that I > didn't have - but it looks like we are learning about this together, > since you are referring to the URL I provided. Yea I ran into this as well. I just disabled dnssec locally and relied on my forwarders to handle it. Your question prompted me to look into it a bit more. > The purpose of my original post was to ask whether this sort of change > in the defaults of an important package belongs in the Arch news page > (https://www.archlinux.org/news/), but I haven't received an answer > yet. I'm open to advice on question-asking or if this is the right > forum or whatever. I could be wrong bit I don't think so, it's an upstream change of a default value. Matt Pallissard
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frederik＠ofb.net
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Pallissard, Matthew