如何强制SSH只允许具有密钥的用户登录？

Question

我试着遵循这里的说明：http://lani78.wordpress.com/2008/08/08/generate-a-ssh-key-and-disable-password-authentication-on-ubuntu-server/

只允许在服务器上具有公钥的用户进行身份验证，但我无法使SSH不允许只使用用户名/密码登录。

这是我的sshd_config文件-我有遗漏什么吗？我已经试过重新启动SSH和计算机本身了。

# Package generated configuration file
# See the sshd_config(5) manpage for details


# What ports, IPs and protocols we listen for
Port 22
# Use these options to restrict which interfaces/protocols sshd will bind to
#ListenAddress ::
#ListenAddress 0.0.0.0
Protocol 2
# HostKeys for protocol version 2
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
#Privilege Separation is turned on for security
UsePrivilegeSeparation yes


# Lifetime and size of ephemeral version 1 server key
KeyRegenerationInterval 3600
ServerKeyBits 768


# Logging
SyslogFacility AUTH
LogLevel INFO


# Authentication:
LoginGraceTime 120
PermitRootLogin yes
StrictModes yes


RSAAuthentication yes
PubkeyAuthentication yes
#AuthorizedKeysFile        %h/.ssh/authorized_keys


# Don't read the user's ~/.rhosts and ~/.shosts files
IgnoreRhosts yes
# For this to work you will also need host keys in /etc/ssh_known_hosts
RhostsRSAAuthentication no
# similar for protocol version 2
HostbasedAuthentication no
# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication
#IgnoreUserKnownHosts yes


# To enable empty passwords, change to yes (NOT RECOMMENDED)
PermitEmptyPasswords no


# Change to yes to enable challenge-response passwords (beware issues with
# some PAM modules and threads)
ChallengeResponseAuthentication no


# Change to no to disable tunnelled clear text passwords
#PasswordAuthentication no


# Kerberos options
#KerberosAuthentication no
#KerberosGetAFSToken no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes


# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes


X11Forwarding yes
X11DisplayOffset 10
PrintMotd no
PrintLastLog yes
TCPKeepAlive yes
#UseLogin no


#MaxStartups 10:30:60
#Banner /etc/issue.net


# Allow client to pass locale environment variables
AcceptEnv LANG LC_*


Subsystem sftp /usr/lib/openssh/sftp-server


# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
UsePAM no

Answer 1

默认情况下，PasswordAuthentication设置为yes，因此在/etc/ssh/sshd_config中显式注释它并重新启动sshd没有任何效果。

您需要显式地将PasswordAuthentication no设置为只允许公钥身份验证。

# To disable tunneled clear text passwords, change to no here!
PasswordAuthentication no

PubkeyAuthentication yes

注意(man sshd_config)：PasswordAuthentication指定是否允许密码身份验证。默认情况是肯定的。

并重新启动sshd

• 用于sysvinit service ssh restart
• 用于systemd systemctl restart sshd.service。

此外，最佳实践是使用以下指令(顺序) DenyUsers AllowUsers DenyGroups AllowGroups来实现更精细的SSH访问控制粒度和灵活性。->引用：sshd_配置5男子 -> Ubuntu手册页不再包含此内容，因为它吸收了openssh上游文档(但是FreeBSD、EL 7、8手册页仍然有它们)。

最后但并非最不重要

注意:请注意将UsePAM no设置为这样的方式:密码锁定用户帐户(这不同于禁用/过期的用户帐户->、man passwd和man usermod)将无法登录，即使它们具有在~/.ssh/authorized_keys中配置的公钥身份验证。

Answer 2

根据这个关于SSH键的wiki页面和这个回答，您需要在您的sshd_config中更改这两行：

PasswordAuthentication no
ChallengeResponseAuthentication no

Answer 3

在/etc/ssh/sshd_config中，下面的设置适用于我：

PasswordAuthentication no
UsePAM no

最后，重新启动sshd守护进程。