我想配置 sshd 以允许用户使用密钥对进行身份验证，然后回退到密码身份验证。但我正在努力从手册页/ sshd_config 文件中的信息中实现这一点。
我的 sshd_config：
Protocol 2
SyslogFacility AUTHPRIV
RSAAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile .ssh/authorized_keys
PasswordAuthentication yes
ChallengeResponseAuthentication no
GSSAPIAuthentication yes
GSSAPICleanupCredentials yes
UsePAM yes
AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
AcceptEnv LC_IDENTIFICATION LC_ALL
X11Forwarding yes
Subsystem sftp /usr/libexec/openssh/sftp-server
当我连接时，看起来好像正在发送私钥 - 但仍然提示我输入密码：
[colinm@server bin]$ ssh -v colinm@dev-server
OpenSSH_4.3p2, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to dev-server [10.168.172.81] port 22.
debug1: Connection established.
debug1: identity file /home/colinm/.ssh/identity type -1
debug1: identity file /home/colinm/.ssh/id_rsa type 1
debug1: identity file /home/colinm/.ssh/id_dsa type -1
debug1: loaded 3 keys
debug1: Remote protocol version 2.0, remote software version OpenSSH_4.3
debug1: match: OpenSSH_4.3 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.3
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'dev-server' is known and matches the RSA host key.
debug1: Found key in /home/colinm/.ssh/known_hosts:10
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-with-mic,password
debug1: Next authentication method: gssapi-with-mic
debug1: Unspecified GSS failure. Minor code may provide more information
No credentials cache found
debug1: Unspecified GSS failure. Minor code may provide more information
No credentials cache found
debug1: Unspecified GSS failure. Minor code may provide more information
No credentials cache found
debug1: Next authentication method: publickey
debug1: Trying private key: /home/colinm/.ssh/identity
debug1: Offering public key: /home/colinm/.ssh/id_rsa
debug1: Authentications that can continue: publickey,gssapi-with-mic,password
debug1: Trying private key: /home/colinm/.ssh/id_dsa
debug1: Next authentication method: password
colinm@dev-server's password:
是否有可能让服务器接受任一作为身份验证机制？
（是的，公钥被复制到〜/.ssh/authorized_keys，并且我使用此配置重新启动了sshd）。
更多调试显示密钥对没有失败：
...
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /home/colinm/.ssh/identity
debug3: no such identity: /home/colinm/.ssh/identity
debug1: Offering public key: /home/colinm/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,gssapi-with-mic,password
debug1: Trying private key: /home/colinm/.ssh/id_dsa
debug3: no such identity: /home/colinm/.ssh/id_dsa
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: ,password
答案1
通常sshd允许公钥身份验证、密码身份验证以及您已启用的其他身份验证。从输出中您可以看到首先尝试了 GSSAPI，但没有成功。接下来提供公钥，但未被接受，最后密码身份验证要求您输入密码。如果您输入错误的密码（或者该帐户的登录被禁用），它将失败，您将一无所获。
尽管您已将公钥上传到~/.ssh/authorized_keys文件中，但这还不足以使密钥身份验证正常工作。该sshd服务对权限也相当严格。目录的~/.ssh模式应为 700，文件的模式应为 600。目录的所有者~/.ssh应该是用户本身，而不是 root 或其他任何人。