Eu resolvi isso. O PAM contém arquivos diferentes e um dos arquivos common-auth foi mal configurado. Houve status de negação em qualquer login inválido, então eu mudei e o problema foi resolvido.
Eu estou tentando fazer o login na máquina Debian 9 com nome de usuário root, localmente e através do ssh. Ele faz o login com qualquer senha inválida. Quero acessar a máquina apenas com a senha correta. Por que uma senha inválida para a conta root funciona? Como posso corrigi-lo para que a entrada de senha correta seja necessária, localmente e por meio do ssh?
Para ssh, permiti apenas o usuário root. Curiosamente, quando eu altero o UsePAM para não, ele funciona com a senha de root correta.
resultado de depuração do ssh :
OpenSSH_7.9p1 Debian-1, OpenSSL 1.1.1 11 Sep 2018
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to 192.168.56.101 [192.168.56.101] port 22.
debug1: Connection established.
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_rsa-cert type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: identity file /root/.ssh/id_dsa-cert type -1
debug1: identity file /root/.ssh/id_ecdsa type -1
debug1: identity file /root/.ssh/id_ecdsa-cert type -1
debug1: identity file /root/.ssh/id_ed25519 type -1
debug1: identity file /root/.ssh/id_ed25519-cert type -1
debug1: identity file /root/.ssh/id_xmss type -1
debug1: identity file /root/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.9p1 Debian-1
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.4p1 Debian-10+deb9u4
debug1: match: OpenSSH_7.4p1 Debian-10+deb9u4 pat OpenSSH_7.0*,OpenSSH_7.1*,OpenSSH_7.2*,OpenSSH_7.3*,OpenSSH_7.4*,OpenSSH_7.5*,OpenSSH_7.6*,OpenSSH_7.7* compat 0x04000002
debug1: Authenticating to localhost:22 as 'root'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
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-nistp256 SHA256:>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
debug1: Host 'localhost' is known and matches the ECDSA host key.
debug1: Found key in /root/.ssh/known_hosts:3
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey after 134217728 blocks
debug1: Will attempt key: /root/.ssh/id_rsa
debug1: Will attempt key: /root/.ssh/id_dsa
debug1: Will attempt key: /root/.ssh/id_ecdsa
debug1: Will attempt key: /root/.ssh/id_ed25519
debug1: Will attempt key: /root/.ssh/id_xmss
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ssh-rsa,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/id_rsa
debug1: Trying private key: /root/.ssh/id_dsa
debug1: Trying private key: /root/.ssh/id_ecdsa
debug1: Trying private key: /root/.ssh/id_ed25519
debug1: Trying private key: /root/.ssh/id_xmss
debug1: Next authentication method: password
debug1: Authentication succeeded (password).
Authenticated to localhost ([localhost]:22).
debug1: channel 0: new [client-session]
debug1: Requesting [email protected]
debug1: Entering interactive session.
debug1: pledge: network
debug1: client_input_global_request: rtype [email protected] want_reply 0
debug1: Sending environment.
debug1: Sending env LANG = en_US.UTF-8
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug1: client_input_channel_req: channel 0 rtype [email protected] reply 0
debug1: channel 0: free: client-session, nchannels 1
debug1: fd 2 clearing O_NONBLOCK
Connection to localhost closed.
Transferred: sent 2356, received 6188 bytes, in 7.3 seconds
Bytes per second: sent 321.4, received 844.0
debug1: Exit status 0