Encontrei a resposta daqui: link
Basicamente eu tenho que adicionar isso ao ~/.ssh/config :
IdentitiesOnly yes
O cliente é o Ubuntu 16.04 com keychain , o servidor é o FreeBSD 10.3. Existe apenas uma chave em ~/.ssh/authorized_keys no servidor (esta chave é ECDSA p521 e não RSA), e o cliente tem chaves privadas e públicas dentro de ~/.ssh . O problema é que o cliente continua enviando todas as chaves RSA disponíveis em ~/.ssh primeiro - veja esta saída detalhada:
OpenSSH_7.2p2 Ubuntu-4, OpenSSL 1.0.2g-fips 1 Mar 2016
debug1: Reading configuration data /home/manuth/.ssh/config
debug1: /home/manuth/.ssh/config line 1: Applying options for r2d2.manuth.life
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to r2d2.manuth.life [103.12.163.90] port 900.
debug1: Connection established.
debug1: identity file /home/manuth/.ssh/dqar type 3
debug1: key_load_public: No such file or directory
debug1: identity file /home/manuth/.ssh/dqar-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.2p2 Ubuntu-4
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2 FreeBSD-20160310
debug1: match: OpenSSH_7.2 FreeBSD-20160310 pat OpenSSH* compat 0x04000000
debug1: Authenticating to r2d2.manuth.life:900 as 'manuth'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: [email protected]
debug1: kex: host key algorithm: ecdsa-sha2-nistp521
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp521 SHA256:awtuO9udROeroYOv3GJ8Z6xcHt4IQhjNkcKQ6eavuik
debug1: Host '[r2d2.manuth.life]:900' is known and matches the ECDSA host key.
debug1: Found key in /home/manuth/.ssh/known_hosts:10
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: manuth@wackypc
debug1: Authentications that can continue: publickey
debug1: Offering RSA public key: manuth@wackypc
debug1: Authentications that can continue: publickey
debug1: Offering RSA public key: manuth@wackypc
debug1: Authentications that can continue: publickey
debug1: Offering ECDSA public key: /home/manuth/.ssh/dqar
debug1: Server accepts key: pkalg ecdsa-sha2-nistp521 blen 172
debug1: Authentication succeeded (publickey).
Authenticated to r2d2.manuth.life ([103.12.163.90]:900).
Ainda a mesma saída, mesmo quando eu especificar isso em ~/.ssh/config no cliente:
host r2d2.manuth.life
IdentityFile ~/.ssh/dqar
Port 900
Tentei remover todas as chaves de keychain , mas não ajuda. Se eu adicionar uma chave pública RSA ao servidor, em seguida, especificar a chave privada RSA em ~/.ssh/config no cliente, ele selecionará a chave RSA imediatamente.
Encontrei a resposta daqui: link
Basicamente eu tenho que adicionar isso ao ~/.ssh/config :
IdentitiesOnly yes