SSHの設定

SSHの設定

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　SSHは標準でrootでのログインを許可しています。これを不許可にしておくと、少し幸せになれます。
# vi /etc/ssh/sshd_config
とすると、以下のようになっています。
================================================================
#AFSTokenPassing no

# Kerberos TGT Passing only works with the AFS kaserver
#KerberosTgtPassing no

#       $OpenBSD: sshd_config,v 1.56 2002/06/20 23:37:12 markus Exp $

# This is the sshd server system-wide configuration file. See
# sshd_config(5) for more information.

# This sshd was compiled with PATH=/usr/local/bin:/bin:/usr/bin

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented. Uncommented options change a
# default value.

#Port 22
#Protocol 2,1
#ListenAddress 0.0.0.0
#ListenAddress ::

# HostKey for protocol version 1
#HostKey /etc/ssh/ssh_host_key
# HostKeys for protocol version 2
#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_dsa_key

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

# Logging
#obsoletes QuietMode and FascistLogging
#SyslogFacility AUTH
SyslogFacility AUTHPRIV
#LogLevel INFO

# Authentication:

#LoginGraceTime 600
#PermitRootLogin yes # ここです
#StrictModes yes

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

# rhosts authentication should not be used
#RhostsAuthentication no
# 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/ssh_known_hosts
#RhostsRSAAuthentication no
# similar for protocol version 2
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# RhostsRSAAuthentication and HostbasedAuthentication
#IgnoreUserKnownHosts no

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

# Change to no to disable s/key passwords
#ChallengeResponseAuthentication yes

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

#AFSTokenPassing no

# Kerberos TGT Passing only works with the AFS kaserver
#KerberosTgtPassing no

# Set this to 'yes' to enable PAM keyboard-interactive authentication
# Warning: enabling this may bypass the setting of 'PasswordAuthentication'
#PAMAuthenticationViaKbdInt yes

#X11Forwarding no
X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
#PrintMotd yes
#PrintLastLog yes
#KeepAlive yes
#UseLogin no
#UsePrivilegeSeparation yes
#Compression yes

#MaxStartups 10
# no default banner path
#Banner /some/path
#VerifyReverseMapping no

# override default of no subsystems
Subsystem       sftp    /usr/libexec/openssh/sftp-server
================================================================
途中に
====================
#PermitRootLogin yes
====================
という記述があります。
これを
====================
PermitRootLogin no
====================
とします。

＜もっと幸せになれる方法＞
$ su -
で、rootになれるユーザーを限定します。
たとえば、pyzarをrootになれるユーザーにするのであれば、まず
# vi /etc/login.defs
とします。
=============================================================
# *REQUIRED*
#   Directory where mailboxes reside, _or_ name of file, relative to the
#   home directory. If you _do_ define both, MAIL_DIR takes precedence.
#   QMAIL_DIR is for Qmail
#
#QMAIL_DIR      Maildir
MAIL_DIR        /var/spool/mail
#MAIL_FILE      .mail

# Password aging controls:
#
#       PASS_MAX_DAYS   Maximum number of days a password may be used.
#       PASS_MIN_DAYS   Minimum number of days allowed between password changes.
#       PASS_MIN_LEN    Minimum acceptable password length.
#       PASS_WARN_AGE   Number of days warning given before a password expires.
#
PASS_MAX_DAYS   99999
PASS_MIN_DAYS   0
PASS_MIN_LEN    5
PASS_WARN_AGE   7

#
# Min/max values for automatic uid selection in useradd
#
UID_MIN                   500
UID_MAX                 60000

#
# Min/max values for automatic gid selection in groupadd
#
GID_MIN                   500
GID_MAX                 60000

#
# If defined, this command is run when removing a user.
# It should remove any at/cron/print jobs etc. owned by
# the user to be removed (passed as the first argument).
#
#USERDEL_CMD    /usr/sbin/userdel_local

#
# If useradd should create home directories for users by default
# On RH systems, we do. This option is ORed with the -m flag on
# useradd command line.
#
CREATE_HOME     yes
=============================================================
この、ファイルの最後の行に以下を追加します。
======================
SU_WHEEL_ONLY   yes
======================
次に
# vi /etc/group
とします。
=======================================
root:x:0:root
bin:x:1:root,bin,daemon
daemon:x:2:root,bin,daemon
sys:x:3:root,bin,adm
adm:x:4:root,adm,daemon
tty:x:5:
disk:x:6:root
lp:x:7:daemon,lp
mem:x:8:
kmem:x:9:
wheel:x:10:root # ここです
以下略
=======================================
これを以下に変更します。
=======================================
root:x:0:root
bin:x:1:root,bin,daemon
daemon:x:2:root,bin,daemon
sys:x:3:root,bin,adm
adm:x:4:root,adm,daemon
tty:x:5:
disk:x:6:root
lp:x:7:daemon,lp
mem:x:8:
kmem:x:9:
wheel:x:10:root,pyzar # ここです
以下略
=======================================
さらに、
# vi /etc/pam.d/su
とします。
===================================================================
#%PAM-1.0
auth       sufficient   /lib/security/pam_rootok.so
# Uncomment the following line to implicitly trust users in the "wheel" group.
#auth       sufficient   /lib/security/pam_wheel.so trust use_uid
# Uncomment the following line to require a user to be in the "wheel" group.
#auth       required     /lib/security/pam_wheel.so use_uid # ここです
auth       required     /lib/security/pam_stack.so service=system-auth
account    required     /lib/security/pam_stack.so service=system-auth
password   required     /lib/security/pam_stack.so service=system-auth
session    required     /lib/security/pam_stack.so service=system-auth
session    optional     /lib/security/pam_xauth.so
====================================================================
これを以下に変更します。
６行目のコメントをはずすだけです。
===================================================================
#%PAM-1.0
auth       sufficient   /lib/security/pam_rootok.so
# Uncomment the following line to implicitly trust users in the "wheel" group.
#auth       sufficient   /lib/security/pam_wheel.so trust use_uid
# Uncomment the following line to require a user to be in the "wheel" group.
auth    required    /lib/security/pam_wheel.so use_uid   # ここです
auth       required     /lib/security/pam_stack.so service=system-auth
account    required     /lib/security/pam_stack.so service=system-auth
password   required     /lib/security/pam_stack.so service=system-auth
session    required     /lib/security/pam_stack.so service=system-auth
session    optional     /lib/security/pam_xauth.so
====================================================================
これで、また少し幸せになれます。

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