我有一个名为的系统用户用户1（主要的）。我尝试在名为外国用户以及主要的（用户1）。为此，我使用 生成了几个密钥ssh-keygen。我添加了外国用户到.ssh/授权密钥用户文件用户1。我已检查.ssh文件夹（700）和.ssh/授权密钥文件 (600)。一切正常。我可以连接用户1从外国用户。
现在，我添加了一个名为用户2（我使用的是 Kubuntu）。我重复了完全相同的步骤。但这次，当我尝试连接时用户2从外国用户，我得到了这个：
Connection closed by 192.168.0.201
但是，如果我转到文件/etc/ssh/sshd_config并将行切换usePAM yes为usePAM no，保存并重新启动 ssh 服务，我就可以连接用户2从外国用户。
会发生什么？如果usePAM设置为yes，并且我尝试使用 进行 ssh 连接-vvv，则会得到以下信息：
OpenSSH_6.2p2 Ubuntu-6ubuntu0.4, OpenSSL 1.0.1e 11 Feb 2013
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to 192.168.0.201 [192.168.0.201] port 8022.
debug1: Connection established.
debug3: Incorrect RSA1 identifier
debug3: Could not load "/home/foreignuser/.ssh/id_rsa" as a RSA1 public key
debug1: identity file /home/foreignuser/.ssh/id_rsa type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-4096
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-4096
debug1: identity file /home/foreignuser/.ssh/id_rsa-cert type -1
debug1: identity file /home/foreignuser/.ssh/id_dsa type -1
debug1: identity file /home/foreignuser/.ssh/id_dsa-cert type -1
debug1: identity file /home/foreignuser/.ssh/id_ecdsa type -1
debug1: identity file /home/foreignuser/.ssh/id_ecdsa-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.2p2 Ubuntu-6ubuntu0.4
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.2p2 Ubuntu-6ubuntu0.4
debug1: match: OpenSSH_6.2p2 Ubuntu-6ubuntu0.4 pat OpenSSH*
debug2: fd 3 setting O_NONBLOCK
debug3: put_host_port: [192.168.0.201]:8022
debug3: load_hostkeys: loading entries for host "[192.168.0.201]:8022" from file "/home/foreignuser/.ssh/known_hosts"
debug3: load_hostkeys: found key type ECDSA in file /home/foreignuser/.ssh/known_hosts:31
debug3: load_hostkeys: loaded 1 keys
debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],[email protected],[email protected],ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,[email protected],[email protected],aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,[email protected],[email protected],aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-md5,hmac-sha1,[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-md5,hmac-sha1,[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,[email protected],zlib
debug2: kex_parse_kexinit: none,[email protected],zlib
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: kex_parse_kexinit: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss,ecdsa-sha2-nistp256
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,[email protected],[email protected],aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,[email protected],[email protected],aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-md5,hmac-sha1,[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-md5,hmac-sha1,[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,[email protected]
debug2: kex_parse_kexinit: none,[email protected]
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: mac_setup: found [email protected]
debug1: kex: server->client aes128-ctr [email protected] none
debug2: mac_setup: found [email protected]
debug1: kex: client->server aes128-ctr [email protected] none
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ECDSA 80:e4:73:c4:4d:a9:30:97:08:3c:f9:f8:ab:80:f4:72
debug3: put_host_port: [192.168.0.201]:8022
debug3: put_host_port: [192.168.0.201]:8022
debug3: load_hostkeys: loading entries for host "[192.168.0.201]:8022" from file "/home/foreignuser/.ssh/known_hosts"
debug3: load_hostkeys: found key type ECDSA in file /home/foreignuser/.ssh/known_hosts:31
debug3: load_hostkeys: loaded 1 keys
debug3: load_hostkeys: loading entries for host "[192.168.0.201]:8022" from file "/home/foreignuser/.ssh/known_hosts"
debug3: load_hostkeys: found key type ECDSA in file /home/foreignuser/.ssh/known_hosts:31
debug3: load_hostkeys: loaded 1 keys
debug1: Host '[192.168.0.201]:8022' is known and matches the ECDSA host key.
debug1: Found key in /home/foreignuser/.ssh/known_hosts:31
debug1: ssh_ecdsa_verify: signature correct
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /home/foreignuser/.ssh/id_rsa (0x7fc896efb2a0),
debug2: key: /home/foreignuser/.ssh/id_dsa ((nil)),
debug2: key: /home/foreignuser/.ssh/id_ecdsa ((nil)),
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 RSA public key: /home/foreignuser/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Server accepts key: pkalg ssh-rsa blen 535
debug2: input_userauth_pk_ok: fp 8d:1e:b2:59:64:e5:07:bf:5c:9e:5b:ad:45:8a:c8:c2
debug3: sign_and_send_pubkey: RSA 8d:1e:b2:59:64:e5:07:bf:5c:9e:5b:ad:45:8a:c8:c2
debug1: read PEM private key done: type RSA
Connection closed by 192.168.0.201