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  1. MINA SSHD
  2. SSHD-1118

Unable to connect with Fedora 33 which has dropped ssh-rsa from PubkeyAcceptedKeyTypes

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Information Provided
    • Affects Version/s: 2.4.0
    • Fix Version/s: None
    • Labels:
      None

      Description

      This problem was noted with Gerrit using a 2.4.0 mina sshd server [1] after a recent upgrade.  Some users using Fedora 33 started being not able to log in.

      It turns out that Fedora >=33 has dropped rsa-ssh from it's default PubkeyAcceptedKeyTypes in /etc/crypto-policies/back-ends/openssh.config.  You either have to modify your policy globally to "legacy" with "update-crypto-policies" or manually set PubkeyAcceptedKeyTypes=ssh-rsa for failing servers.

      I understand that server-sig-algs support isn't fully implemented in mina sshd as yet, so the client will not be seeing the negotiation list.

      However, it seems rsa-sha2-256/512 are supported?  It seems like forcing this with ssh -oPubkeyAcceptedKeyTypes=rsa-sha2-512 should work, but it does not (see related gerrit bug)?

      I can provide ssh connect logs, etc. if it will help; at this point I think it's mostly about understanding Fedora's change and any mina limitations so we can find the best solution for users.  Although Fedora 33 users are obviously a small minority now, it probably flags something other distros will take up sooner or later.

       

      Thanks!

       

       [1] https://bugs.chromium.org/p/gerrit/issues/detail?id=13930

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              • Assignee:
                Unassigned
                Reporter:
                iwienand Ian Wienand
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