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如何以 root 身份登录到云实例？

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如何以 root 身份登录到云实例？

我可以通过 SSH 以用户“ubuntu”身份成功登录到我的云实例，但无法以用户“root”身份登录。目前有几篇帖子涉及更改 ssh 配置以允许 root 访问，但我没有一个成功。例如，我对 /etc/ssh/sshd_config 文件进行了常规更改，即：

#Authentication
PermitRootLogin yes

这没有效果。

现在，当我尝试以“root”身份登录时收到的消息是：

请以用户“ubuntu”而不是“root”身份登录。

搜索“请登录”，我在'/usr/lib/python3/dist-packages/cloudinit/config/cc_ssh.py'文件（所有地方）中发现以下几行：

DISABLE_ROOT_OPTS = (
"no-port-forwarding,no-agent-forwarding,"
"no-X11-forwarding,command=\"echo \'Please login as the user \\\"$USER\\\""
" rather than the user \\\"root\\\".\';echo;sleep 10\"")

我对此不太理解。我猜想这个 Python 脚本是在首次创建实例时运行的，并且负责某些阻止我以“root”身份登录的附加 SSH 设置。

在我看来，有问题的 ssh 配置指令是“no-X11-forwarding”和另外两个。我得出这个结论是因为它们似乎与有问题的消息有关。

我猜想该command指令指示 ssh 守护程序在违反相关指令时显示此消息。我猜对了吗？

我要补充的是，我知道反对以 root 用户身份登录的论点。但是，这是一个私人实例，我将是唯一的用户。我需要以“root”身份进行 ssh 访问，因为我的部署脚本需要以 root 身份运行，以避免复杂化。

更新：下面提到的python脚本是Ubuntu的一部分云初始化包裹。

进一步更新：以下是 /etc/pam.d/sshd 文件的内容...

# PAM configuration for the Secure Shell service

# Standard Un*x authentication.
@include common-auth

# Disallow non-root logins when /etc/nologin exists.
account    required     pam_nologin.so

# Uncomment and edit /etc/security/access.conf if you need to set complex
# access limits that are hard to express in sshd_config.
# account  required     pam_access.so

# Standard Un*x authorization.
@include common-account

# SELinux needs to be the first session rule.  This ensures that any
# lingering context has been cleared.  Without this it is possible that a
# module could execute code in the wrong domain.
session [success=ok ignore=ignore module_unknown=ignore default=bad]        pam_selinux.so close

# Set the loginuid process attribute.
session    required     pam_loginuid.so

# Create a new session keyring.
session    optional     pam_keyinit.so force revoke

# Standard Un*x session setup and teardown.
@include common-session

# Print the message of the day upon successful login.
# This includes a dynamically generated part from /run/motd.dynamic
# and a static (admin-editable) part from /etc/motd.
session    optional     pam_motd.so  motd=/run/motd.dynamic
session    optional     pam_motd.so noupdate

# Print the status of the user's mailbox upon successful login.
session    optional     pam_mail.so standard noenv # [1]

# Set up user limits from /etc/security/limits.conf.
session    required     pam_limits.so

# Read environment variables from /etc/environment and
# /etc/security/pam_env.conf.
session    required     pam_env.so # [1]
# In Debian 4.0 (etch), locale-related environment variables were moved to
# /etc/default/locale, so read that as well.
session    required     pam_env.so user_readenv=1 envfile=/etc/default/locale

# SELinux needs to intervene at login time to ensure that the process starts
# in the proper default security context.  Only sessions which are intended
# to run in the user's context should be run after this.
session [success=ok ignore=ignore module_unknown=ignore default=bad]        pam_selinux.so open

# Standard Un*x password updating.
@include common-password

...以及 /etc/ssh/sshd_config 文件的内容...

# 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
HostKey /etc/ssh/ssh_host_ed25519_key
#Privilege Separation is turned on for security
UsePrivilegeSeparation yes

# Lifetime and size of ephemeral version 1 server key
KeyRegenerationInterval 3600
ServerKeyBits 1024

# 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 yes

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

# 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 yes

...按照要求。

答案1

查看该/root/.ssh/authorized_keys文件。你很可能会发现类似这样的内容：

root@instance-00:~# cat /root/.ssh/authorized_keys 
no-port-forwarding,no-agent-forwarding,no-X11-forwarding,command="echo 'Please login as the user \"ubuntu\" rather than the user \"root\".';echo;sleep 10" ssh-rsa AAAA...= user@host

（这是从不同的云提供商那里获得的，但配置似乎与亚马逊的相同）。

只需删除前面的所有内容ssh-rsa，您就应该能够以 root 身份远程登录（当然，其他人已经告诉过您这不是最佳做法的所有内容仍然适用！）

如果您真的很懒，您可以authorized_keys使用用户的文件覆盖该文件ubuntu：

root@instance-00:~# cp /home/ubuntu/.ssh/authorized_keys /root/.ssh/authorized_keys

如果你好奇这个前缀是怎么来的，你已经找到的相同 Python 代码 ( /usr/lib/python3/dist-packages/cloudinit/config/cc_ssh.py) 中有答案apply_credentials。请注意它如何设置授权密钥的前缀：

if disable_root:
    if not user:
        user = "NONE"
    key_prefix = disable_root_opts.replace('$USER', user)
else:
    key_prefix = ''

答案2

强烈建议阻止远程root登录服务器（出于安全原因）。

建议的方式是以普通用户身份登录，并使用sudo以获得root访问权限。

sudo为您提供每个命令的完全访问权限的最终命令root是：

sudo bash

对于应该执行的特定命令，root您可以使用：

sudo specific-command

执行命令的示例如下root：

sudo ls -lsa /root

注意：如果你想更改亚马逊政策并允许root登录，你可以使用以下答案amazon-ec2-root-login SO问答

参考下面设置root登录：

sudo -s (to become root)
vi /root/.ssh/authorized_keys

删除文件开头的行，直到看到单词ssh-rsa。

vi /etc/ssh/sshd_config

将变量设置PermitRootLogin为PermitRootLogin without-password（不带引号）

sudo /etc/init.d/sshd restart

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