Hi Steve, thanks for bringing that up and debugging that much already. In regard to this issue you kind of continued in bug 1694161. You outlined there that the reason this hit you more than others was that you added a /etc/resolvconf/resolv.conf.d/tail to make libvirts dns resolution known in the host. I like the suggestion you made there as a proper solution via libvirt registering "correctly" into systemd resolvd.
I wondered if I should close the bug here as a dup to the other one then. But since this will take time to be worked on, upstreamed, and so on I wondered if you tried to add "--dns-loop-detect" as a workaround for your setup. It might break the DNS forwarding loops, but retain the name resolution you wanted. Do you think that is worth a try? -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/1694156 Title: systemd-resolved and libvirt dnsmasq instance get into a busy loop when a query is issued for a URI or SRV record Status in dnsmasq package in Ubuntu: New Status in libvirt package in Ubuntu: New Status in systemd package in Ubuntu: New Bug description: I have a zesty system that uses systemd-resolved, as per default, which also has dnsmasq configured for use on interface virbr0 for my libvirt bridge. This system is also part of a Kerberos realm. Recent versions of Kerberos do a lookup of a URI RR, à la: $ nslookup -q=URI _kerberos.dodds.net Server: 127.0.0.53 Address: 127.0.0.53#53 Non-authoritative answer: *** Can't find _kerberos.dodds.net: No answer Authoritative answers can be found from: $ There is no URI DNS record published for this domain, so the lack of response is correct. However, systemd-resolved and dnsmasq then get in a busy loop, passing the same query back and forth between each other. (Confirmed with wireshark.) If I query SRV records under the same domain (which is also part of what kerberos does), these positive results are correctly returned to the client, but systemd-resolved and dnsmasq again get into a busy loop. If I query a URI record for a domain /other than/ what I have configured as my DNS search domain, there is no busy loop. If I query other kinds of records (whether they return results or not), such as A, CNAME, and MX records, there is no busy loop. /etc/resolv.conf looks like: # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN # 127.0.0.53 is the systemd-resolved stub resolver. # run "systemd-resolve --status" to see details about the actual nameservers. domain dodds.net search dodds.net nameserver 127.0.0.53 nameserver 192.168.122.1 systemd-resolve says: $ systemd-resolve --status Global DNS Servers: 192.168.122.1 DNS Domain: dodds.net DNSSEC NTA: 10.in-addr.arpa 16.172.in-addr.arpa 168.192.in-addr.arpa 17.172.in-addr.arpa 18.172.in-addr.arpa 19.172.in-addr.arpa 20.172.in-addr.arpa 21.172.in-addr.arpa 22.172.in-addr.arpa 23.172.in-addr.arpa 24.172.in-addr.arpa 25.172.in-addr.arpa 26.172.in-addr.arpa 27.172.in-addr.arpa 28.172.in-addr.arpa 29.172.in-addr.arpa 30.172.in-addr.arpa 31.172.in-addr.arpa corp d.f.ip6.arpa home internal intranet lan local private test [...] Link 2 (wlan2) Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6 LLMNR setting: yes MulticastDNS setting: no DNSSEC setting: no DNSSEC supported: no DNS Servers: 192.168.0.1 DNS Domain: dodds.net $ I'm not sure where this bug lies. Both DNS servers are by design configured not to cache results, in order to avoid cache poisoning and information leaks, so neither DNS server can detect that they've already asked for the record and don't need to recurse. I think it's probably a bug for dnsmasq to be configured as a server for resolving 'dodds.net' - I have nowhere specified that this is appropriate and this potentially conflicts with legitimate records in this domain. But it also must be a bug that SRV/URI records result in recursion but A/CNAME/MX records do not. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/1694156/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
