PubkeyAcceptedKeyTypes=+ssh-dss You also need that ^^ in their client if they are running on el8 machine as well .. i needed to put it in my ~/.ssh/config when connecting FROM an el8 machine to somewhere else. On 10/17/19 9:27 AM, Gianluca Cecchi wrote: > Hello, > I have some users that connect to a server with their DSA key that is of > type ssh-dss. > I'm migrating (installing as new) the server where they connect to CentOS 8 > + updates. > I was not able to connect with the keys to this new server even after > having added, as found in several internet pages, this directive at the end > of /etc/ssh/sshd_config of the CentOS 8 server: > > # Accept also DSA keys > PubkeyAcceptedKeyTypes=+ssh-dss > > and > systemctl restart sshd > > I kept getting in journal the message: > userauth_pubkey: key type ssh-dss not in PubkeyAcceptedKeyTypes [preauth] > > I saw that the sshd process had started with the option > ... -oPubkeyAcceptedKeyTypes=rsa-sha2-256,ecdsa-sha2-nistp256, > ecdsa-sha2-nistp256-cert-v01 at openssh.com,ecdsa-sha2-nistp384, > ecdsa-sha2-nistp384-cert-v01 at openssh.com,rsa-sha2-512,ecdsa-sha2-nistp521, > ecdsa-sha2-nistp521-cert-v01 at openssh.com,ssh-ed25519, > ssh-ed25519-cert-v01 at openssh.com,ssh-rsa,ssh-rsa-cert-v01 at openssh.com > > So I found the unit file for sshd that refers > to /etc/crypto-policies/back-ends/opensshserver.config > In the mean time I was able to reach my target going and editing the > /etc/sysconfig/sshd file adding the whole line obtained from the above and > adding ssh-dss > > CRYPTO_POLICY='-oCiphers=aes256-gcm at openssh.com, > chacha20-poly1305 at openssh.com,aes256-ctr,aes256-cbc,aes128-gcm at openssh.com,aes128-ctr,aes128-cbc > -oMACs=hmac-sha2-256-etm at openssh.com,hmac-sha1-etm at openssh.com, > umac-128-etm at openssh.com,hmac-sha2-512-etm at openssh.com > ,hmac-sha2-256,hmac-sha1,umac-128 at openssh.com,hmac-sha2-512 > -oGSSAPIKexAlgorithms=gss-gex-sha1-,gss-group14-sha1- -oKexAlgorithms= > curve25519-sha256 at libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1 > -oHostKeyAlgorithms=rsa-sha2-256,ecdsa-sha2-nistp256, > ecdsa-sha2-nistp256-cert-v01 at openssh.com,ecdsa-sha2-nistp384, > ecdsa-sha2-nistp384-cert-v01 at openssh.com,rsa-sha2-512,ecdsa-sha2-nistp521, > ecdsa-sha2-nistp521-cert-v01 at openssh.com,ssh-ed25519, > ssh-ed25519-cert-v01 at openssh.com,ssh-rsa,ssh-rsa-cert-v01 at openssh.com > -oPubkeyAcceptedKeyTypes=rsa-sha2-256,ecdsa-sha2-nistp256, > ecdsa-sha2-nistp256-cert-v01 at openssh.com,ecdsa-sha2-nistp384, > ecdsa-sha2-nistp384-cert-v01 at openssh.com,rsa-sha2-512,ecdsa-sha2-nistp521, > ecdsa-sha2-nistp521-cert-v01 at openssh.com,ssh-ed25519, > ssh-ed25519-cert-v01 at openssh.com,ssh-rsa,ssh-rsa-cert-v01 at openssh.com > ,ssh-dss' > > and now it works with pubkey authentication based on DSA keys. > Not going to the querelle of OpenSSH 7 removing DSA keys and DSA vs RSA > (eg. some considerations by some years ago here: > https://security.stackexchange.com/questions/5096/rsa-vs-dsa-for-ssh-authentication-keys > ), > any hint on smarter way to add? > I suppose further updates could change content > of /etc/crypto-policies/back-ends/opensshserver.config that btw is part > of crypto-policies-20181217-6.git9a35207.el8.noarch and > not openssh-server-7.8p1-4.el8.x86_64 > > HIH others incurring in this problem and thanks in advance for any > insight/hint, > Gianluca > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos > -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 198 bytes Desc: OpenPGP digital signature URL: <http://lists.centos.org/pipermail/centos/attachments/20191017/32481aaf/attachment-0005.sig>