Hello: Does anyone here happen to know how to deal with something like this: ........... debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ssh-rsa SHA256:RXNl/GKyDaKiIQ93BoDvrNSKUPFvA1PNeAO9QiirYZU debug1: Host '[review.opendev.org]:29418' is known and matches the RSA host key. debug1: Found key in /q/zaitcev/.ssh/known_hosts:133 debug1: rekey out after 4294967296 blocks debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: rekey in after 4294967296 blocks debug1: Will attempt key: /q/zaitcev/.ssh/id_rsa_ostk2014 RSA SHA256:nz5*** explicit agent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey debug1: Next authentication method: publickey debug1: Offering public key: /q/zaitcev/.ssh/id_rsa_ostk2014 RSA SHA256:nz5*** explicit agent debug1: send_pubkey_test: no mutual signature algorithm debug1: No more authentication methods to try. zaitcev@review.opendev.org: Permission denied (publickey). [zaitcev@suzdal swift-dark]$ I guess that ssh client in Fedora 33 has a cipher suite that has no intersection with the ssh server at review.opendev.org. But I do not understand what the server is offering, so I do not know what I need to enable. Thanks in advance, -- Pete
On 2020-12-26 14:48:27 -0600 (-0600), Pete Zaitcev wrote:
Does anyone here happen to know how to deal with something like this: [...] debug1: Offering public key: /q/zaitcev/.ssh/id_rsa_ostk2014 RSA SHA256:nz5*** explicit agent debug1: send_pubkey_test: no mutual signature algorithm debug1: No more authentication methods to try. [...] I guess that ssh client in Fedora 33 has a cipher suite that has no intersection with the ssh server at review.opendev.org. But I do not understand what the server is offering, so I do not know what I need to enable.
You're basically on track with your assumptions. OpenSSH 8.4 (client included in Fedora 33) has deprecated[*] ssh-rsa authentication because it relies on SHA-1 hashes but Fedora decided[**] to go a step further and update their own crypto policy to just go ahead and break it completely. You might try and see whether the UpdateHostKeys option works around this (our current Gerrit version does have SHA-2 support for RSA keys). Supposedly, switching to using elliptic curve keys (ed25519 or ecdsa) is another way to solve it. If that doesn't do the trick, you can add a host entry for review.opendev.org in your ~/.ssh/config file to set PubkeyAcceptedKeyTypes +rsa-sha2-256,rsa-sha2-512 so that it will look for them. There are also ways to downgrade the security of your connections, but I won't enumerate them here since you presumably chose Fedora 33 for a reason and I would rather not argue against their system security choices. [*] https://www.openssh.com/releasenotes.html [**] https://fedoraproject.org/wiki/Changes/StrongCryptoSettings2 -- Jeremy Stanley
On Sat, 26 Dec 2020 21:14:10 +0000 Jeremy Stanley <fungi@yuggoth.org> wrote:
debug1: send_pubkey_test: no mutual signature algorithm debug1: No more authentication methods to try.
You're basically on track with your assumptions. OpenSSH 8.4 (client included in Fedora 33) has deprecated[*] ssh-rsa authentication because it relies on SHA-1 hashes but Fedora decided[**] to go a step further and update their own crypto policy to just go ahead and break it completely. [*] https://www.openssh.com/releasenotes.html
Jeremy, thanks a lot. That's a piece of documentation that I didn't think to check. I was able to submit my review to Gerrit by allowing ssh-rsa with PubkeyAcceptedKeyTypes. -- Pete
participants (2)
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Jeremy Stanley
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Pete Zaitcev