[Bug 1741176] [NEW] ssh-keyscan returns no key on some hosts

[latimerio]

Public bug reported:

after upgrading our control server to Ubunto 16.04 LTS I do not get a key response from ssh-keyscan from some legacy hosts while others with the same OpenSSH revision work ok.
Here is a sample output where you can see that in the first query that there is just the SSH version displayed but no key part.
The queried hosts are all HP-UX 10.20 with OpenSSH 4.1

ssh-keyscan -t rsa -4 host1
# host1:22 SSH-2.0-OpenSSH_4.1

ssh-keyscan -t rsa -4 host2
# host2:22 SSH-2.0-OpenSSH_4.1
host2 ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEAswUwKzs87EU9Q7gVGIyupZowMT1o8FB+u/DKAy6sgjyZ8/RBGwl0R7DIdNw5U6E9sAwE5tyB4CQp2G39o8YpHDo75co9+ALULiRC+xqaGmvMtY7aipHzlOyE6Sa0t0xKcfPXsk2ekq46S84vzhWy3yIJCHVbTBjiN4NXv96gPBU=

If I do the same on host1 from an Ubuntu 14.04.5 LTS it works
ssh-keyscan -t rsa host1
# host1 SSH-2.0-OpenSSH_4.1
host11 ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEAtBAPXd7KxHoKH52Q8jwPKRM2m9TFdivAyizkOTj7m0YHqdNjohLz6ID/7jlsq+8ou9KjSydpukiwc5goNutb2ndsAd/5+XcqRAGt1TyMxVAF0X5uFoic0QW3AvBORvIkhym36CS2ivMkaYkHaCn9k8XjbVjzXLW4+xmkplWdjXU=

** Affects: openssh (Ubuntu)
     Importance: Undecided
         Status: New

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to openssh in Ubuntu.
https://bugs.launchpad.net/bugs/1741176

Title:
  ssh-keyscan returns no key on some hosts

Status in openssh package in Ubuntu:
  New

Bug description:
  after upgrading our control server to Ubunto 16.04 LTS I do not get a key response from ssh-keyscan from some legacy hosts while others with the same OpenSSH revision work ok.
  Here is a sample output where you can see that in the first query that there is just the SSH version displayed but no key part.
  The queried hosts are all HP-UX 10.20 with OpenSSH 4.1

  ssh-keyscan -t rsa -4 host1
  # host1:22 SSH-2.0-OpenSSH_4.1

  ssh-keyscan -t rsa -4 host2
  # host2:22 SSH-2.0-OpenSSH_4.1
  host2 ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEAswUwKzs87EU9Q7gVGIyupZowMT1o8FB+u/DKAy6sgjyZ8/RBGwl0R7DIdNw5U6E9sAwE5tyB4CQp2G39o8YpHDo75co9+ALULiRC+xqaGmvMtY7aipHzlOyE6Sa0t0xKcfPXsk2ekq46S84vzhWy3yIJCHVbTBjiN4NXv96gPBU=

  If I do the same on host1 from an Ubuntu 14.04.5 LTS it works
  ssh-keyscan -t rsa host1
  # host1 SSH-2.0-OpenSSH_4.1
  host11 ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEAtBAPXd7KxHoKH52Q8jwPKRM2m9TFdivAyizkOTj7m0YHqdNjohLz6ID/7jlsq+8ou9KjSydpukiwc5goNutb2ndsAd/5+XcqRAGt1TyMxVAF0X5uFoic0QW3AvBORvIkhym36CS2ivMkaYkHaCn9k8XjbVjzXLW4+xmkplWdjXU=

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1741176/+subscriptions