[Bug 1897744] Re: VerifyHostKeyDNS not working due to missing trust-ad flag

[Launchpad Bug Tracker]

This bug was fixed in the package systemd - 245.4-4ubuntu3.3

---------------
systemd (245.4-4ubuntu3.3) focal; urgency=medium

  [ Rafael David Tinoco ]
  * d/p/lp1861941-dont-generate-disk-byuuid-for-bcache-uuid.patch:
    Reworded and reintroduced patch to fully explain delta is NOT a fix to
    LP: #1861941 if the bcache-tools patch exists, but should be kept anyway
    as the change makes sense for a better experience to end user.
    (LP: #1861941)
    https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=f8f64b3b58a04a83b1c426818b9affc41e0bff6c

  [ Dan Streetman ]
  * d/p/lp1882596-man-fix-some-manvolnum.patch:
    - fix some man section references (LP: #1882596)
    https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=3959ec95eff78d38ec4409807f151572afe83fe9
  * d/p/lp1895418-correct-resolved-conf-cache-default.patch:
    - fix resolved.conf default Cache= value (LP: #1895418)
    https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=ebe274a2b01658ee39b372d7033c35209510b028
  * d/p/lp1897744-resolve-enable-RES_TRUSTAD-towards-the-127.0.0.53-st.patch:
    - add resolv.conf 'trust-ad' option (LP: #1897744)
    https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=f6acc8c620b80adab7b048352d85e722b5ba8214
  * d/t/*:
    - Update tests to fix false negatives (LP: #1892358)
    https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=cee6c31a6caec7888270c9fa8757105ab950ed0c
    https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=a1c1a2bb0ff27faf84fe94583631dfd0f1f4ed8f
    https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=9417ce996766c133c2a33d4102ce1494f3166774

 -- Dan Streetman <ddstreet at canonical.com>  Thu, 08 Oct 2020 16:14:56
-0400

** Changed in: systemd (Ubuntu Focal)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1897744

Title:
  VerifyHostKeyDNS not working due to missing trust-ad flag

Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  [impact]

  without trust-ad resolv.conf option, glibc will strip AD from systemd-
  resolved responses. one thing this will prevent working is ssh
  VerifyHostKeyDNS

  [test case]

  see
  https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1898590/comments/7

  [regression potential]

  regressions would likely involve DNS lookup failures, probably if
  DNSSEC is enabled but possibly even without, and likely when the
  application requesting the dns lookup processes the response AD.

  [scope]

  this is needed only in focal.

  glibc first stripped the AD in version 2.31, so this is not needed in
  bionic or earlier.

  this was added upstream in commit a742f9828ea which was included in
  v246, so this is fixed already in groovy.

  [original description]

  Hi,

  1)
  Description:	Ubuntu 20.04.1 LTS
  Release:	20.04

  2)
  systemd:        245.4-4ubuntu3.2

  3)
  I set VerifyHostKeyDNS to YES and hosts are automatically verified via sshfp.

  4)
  I still get the security question
  Matching host key fingerprint found in DNS.
  Are you sure you want to continue connecting (yes/no/[fingerprint])?

  The issue is known and fixed in systemd v246.
  https://github.com/systemd/systemd/pull/16072

  Best regards
  Daniel

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