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Sshキー認証は、サーバーに物理的にログインしている場合にのみ機能します

更新：この問題はホームディレクトリの暗号化が原因でした

奇妙な問題があります。 SSH用のキーと無効なパスワードログインを作成してインストールしました。サーバーにSSHで接続しようとすると、 "アクセスが拒否されました（公開鍵）"が表示されます。ただし、モニターとキーボードをサーバーに接続し、サーバー自体にログインすると（SSH経由で接続しているユーザーを使用して）、これと同じラップトップからのssh（キー認証）が突然機能します。

マシンに物理的にログインしているが、物理的にログインしていない場合、リモートSSHが機能する可能性はありますか？

/var/log/auth.logでsshの試行が失敗した場合（syslogにアクティビティがない場合）に取得する唯一の情報は次のとおりです。

sshd[..] Connection closed by authenticating user <myuser> <ip> port <port> [preauth]

ラップトップでキーを作成し、サーバーにコピーして、アクセス許可を変更しました：chmod 700 ~/.ssh chmod 600 ~/.ssh/authorized_keys chown username. ~/.ssh/authorized_keys

sshd_configを変更してパスワードログインを無効にしました：

ChallengeResponseAuthentication no
PasswordAuthentication no
UsePAM no

サーバーに物理的にログインする前に失敗したリモートSSHの完全なログ：

ssh -vvv <myuser>@<myhost>
:qOpenSSH_7.6p1 Ubuntu-4, OpenSSL 1.0.2n  7 Dec 2017
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: resolving "<myhost>" port 22
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to <myhost> [85.148.172.169] port 22.
debug1: Connection established.
debug1: identity file /home/<myuser>/.ssh/id_rsa type 0
debug1: key_load_public: No such file or directory
debug1: identity file /home/<myuser>/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/<myuser>/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/<myuser>/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/<myuser>/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/<myuser>/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/<myuser>/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/<myuser>/.ssh/id_ed25519-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.6p1 Ubuntu-4
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.6p1 Ubuntu-4
debug1: match: OpenSSH_7.6p1 Ubuntu-4 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to <myhost>:22 as '<myuser>'
debug3: hostkeys_foreach: reading file "/home/<myuser>/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/<myuser>/.ssh/known_hosts:12
debug3: load_hostkeys: loaded 1 keys from <myhost>
debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c
debug2: Host key algorithms: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected],zlib
debug2: compression stoc: none,[email protected],zlib
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1
debug2: Host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected]
debug2: compression stoc: none,[email protected]
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
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
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: Server Host key: ecdsa-sha2-nistp256 SHA256:5P8C9BEdtx1FZJ+TqzHNOxnlpJSw1ufmItzAhRW8uTY
debug3: hostkeys_foreach: reading file "/home/<myuser>/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/<myuser>/.ssh/known_hosts:12
debug3: load_hostkeys: loaded 1 keys from <myhost>
debug3: hostkeys_foreach: reading file "/home/<myuser>/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/<myuser>/.ssh/known_hosts:13
debug3: load_hostkeys: loaded 1 keys from 85.148.172.169
debug1: Host '<myhost>' is known and matches the ECDSA Host key.
debug1: Found key in /home/<myuser>/.ssh/known_hosts:12
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug1: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey after 134217728 blocks
debug2: key: /home/<myuser>/.ssh/id_rsa (0x5635443895b0), agent
debug2: key: /home/<myuser>/.ssh/id_dsa ((nil))
debug2: key: /home/<myuser>/.ssh/id_ecdsa ((nil))
debug2: key: /home/<myuser>/.ssh/id_ed25519 ((nil))
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey
debug3: start over, passed a different list publickey
debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering public key: RSA SHA256:tLacXPO8rQRQIoy6xrKfJn2Q9o6bzEhVSnZHAzXtkNM /home/<myuser>/.ssh/id_rsa
debug3: send_pubkey_test
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey
debug1: Trying private key: /home/<myuser>/.ssh/id_dsa
debug3: no such identity: /home/<myuser>/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /home/<myuser>/.ssh/id_ecdsa
debug3: no such identity: /home/<myuser>/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /home/<myuser>/.ssh/id_ed25519
debug3: no such identity: /home/<myuser>/.ssh/id_ed25519: No such file or directory
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
<myuser>@<myhost>: Permission denied (publickey).
sshauthenticationssh-keys
2
robert

まず、設定してください：

UsePAM yes

sshd_configで、sshを再起動します。

# systemctl restart sshd

これはパスワード認証を有効にしません。PAMはユーザーを認証するだけではないため、パスワード認証が必要です。それが問題を解決する可能性があります。

そうでない場合は、ログイン後にユーザーのホームディレクトリをマウントするものがある可能性があります。たぶん、サーバーにはpam_mountやecryptfsなどが構成されていますか？

その場合は、サーバーの/etc/ssh/sshd_configに以下を追加することで、ユーザーごとに許可されたキーファイルのout-of-homedirを構成できます。

AuthorizedKeysFile  /etc/ssh/authorized_keys/%u

次に、ディレクトリがまだ存在しない場合は作成します。

# mkdir /etc/ssh/authorized_keys/
# chmod 755 /etc/ssh/authorized_keys/

sshを再起動します：

# systemctl restart sshd

これで、ユーザーmyuserの承認済みキーを/etc/ssh/authorized_keys/myuserに、644許可ビットを使用してインストールできます。

myuser@server:~$ Sudo cp .ssh/authorized_keys /etc/ssh/authorized_keys/myuser
myuser@server:~$ Sudo chmod 644 /etc/ssh/authorized_keys/myuser
myuser@server:~$ Sudo chown root.root /etc/ssh/authorized_keys/myuser
3
Lucio Crusca