systemd-resolved DNSSEC root trust anchor outdated ?

Marc Deslauriers marc.deslauriers at canonical.com
Sat Jan 12 17:47:26 UTC 2019


On 2019-01-12 9:36 a.m., Marc Deslauriers wrote:
> On 2019-01-11 11:01 p.m., J Doe wrote:
>> Hello,
>>
>> I currently run a server using Ubuntu 18.04.1 LTS with patches current to today (Jan 11, 2019).  I configured systemd-resolved to use DNSSEC validation by editing: /etc/systemd/resolved.conf and setting: DNSSEC=yes.
>>
>> When I check my syslog, I note that systemd-resolved is logging that the positive trust anchor for the root has been revoked:
>>
>> Jan 11 17:59:48 server systemd-resolved[728]: DNSSEC Trust anchor . IN DS 19036 8 2 49aac11d7b6f6446702e54a1607371607a1a41855200fd2ce1cdde32f24e8fb5 has been revoked. Please update the trust anchor, or upgrade your operating system.
>>
>> I checked: man dnssec-trust-anchors.d and read:
>>
>> "Note that systemd-resolved will automatically use a built-in trust anchor key for the Internet root domain if no positive trust anchors are defined for the root domain.”
>>
>> I verified that: /etc/dnssec-trust-anchors.d/*.positive, /run/dnssec-trust-anchors.d/*.positive, /usr/lib/dnssec-trust-anchors.d/*.positive do *NOT* exist, which means that only the compiled in root trust anchor key is being used and that systemd-resolved has found that it has been revoked.
>>
>> Does this require a new root trust anchor to be compiled in and then shipped in a systemd update or should I manually acquire the root trust anchor and place it in one of the directories mentioned in: man dnssec-trust-anchors.d ?
>>
>> For the meantime, I have disabled DNSSEC validation in: /etc/systemd/resolved.conf
>>
>> Thanks,
>>
>> - J
>>
> 
> It looks like resolved in 18.04 does in fact contain both the old and new trusty
> anchors hardcoded in resolved-dns-trusty-anchor.c. A quick look at the file
> suggests the expired one then gets removed from the list and the warning is issued.
> 
> Do you only get the warning once?
> 
> Marc.
> 

Wow, I managed to typo "trust" as "trusty" twice. Stupid muscle memory ;)

Marc.



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