Guide to the Secure Configuration of Oracle Linux 9

• GnuTLS library
• OpenSSL library
• NSS library
• OpenJDK
• Libkrb5
• BIND
• OpenSSH

part / --fstype=ext4 --size=100 --onpart=hda1 --encrypted --passphrase=PASSPHRASE
        

dconf update

/etc/dconf/db/local.d

/etc/dconf/db/local.d

user-db:user
system-db:local
system-db:site
system-db:distro

$ sudo yum install sudo

 sudo cvtsudoers -f sudoers /etc/sudoers | grep -E '^Defaults !?(rootpw|targetpw|runaspw)$' 

 Defaults !targetpw
      Defaults !rootpw
      Defaults !runaspw 

 sudo find /etc/sudoers /etc/sudoers.d \( \! -name '*~' -a \! -name '*.*' \) -exec grep -E --with-filename '^[[:blank:]]*Defaults[[:blank:]](.*[[:blank:]])?!?\b(rootpw|targetpw|runaspw)' -- {} \; 

 /etc/sudoers:Defaults !targetpw
      /etc/sudoers:Defaults !rootpw
      /etc/sudoers:Defaults !runaspw 

$ sudo chgrp root /etc/sudoers.d

$ sudo chown root /etc/sudoers.d 

$ sudo chmod 0750 /etc/sudoers.d

$ sudo chgrp root /etc/sudoers

$ sudo chown root /etc/sudoers 

$ sudo chmod 0440 /etc/sudoers

$ sudo chmod 4111 /usr/bin/sudo

$ sudo yum install gnutls-utils

$ sudo yum install nss-tools

$ sudo yum install openscap-scanner

$ sudo yum install rear

$ sudo yum install rng-tools

$ sudo yum install scap-security-guide

$ sudo yum erase gssproxy

$ sudo yum erase iprutils

$ sudo yum erase tuned

$ sudo yum install dnf-automatic

gpgcheck=1

gpgcheck=0

$ sudo uln_register

$ sudo rpm --import /media/cdrom/RPM-GPG-KEY-oracle

sudo rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-oracle

$ sudo yum update

$ sudo systemctl enable dnf-automatic.timer

$ sudo chgrp root /etc/issue.net

$ sudo chown root /etc/issue.net 

$ sudo chmod 0644 /etc/issue.net

$ sudo grep pam_succeed_if /etc/pam.d/sudo

session     required    pam_lastlog.so showfailed

$ sudo systemctl mask --now debug-shell.service

CtrlAltDelBurstAction=none

ln -sf /dev/null /etc/systemd/system/ctrl-alt-del.target

systemctl mask ctrl-alt-del.target

systemd.confirm_spawn=(1|yes|true|on)

/sbin/grubby --update-kernel=ALL --remove-args="systemd.confirm_spawn"

grub2-mkconfig -o /boot/grub2/grub.cfg

[Login]

StopIdleSessionSec=
        

$ sudo userdel unauthorized_user
        

$ sudo chage -I NUM_DAYS USER
        

$ sudo chage -M 180 -m 7 -W 7 USER

CREATE_HOME yes

FAIL_DELAY 
        

* hard maxlogins 
        

$ sudo mkdir --mode 000 /tmp/tmp-inst

/tmp     /tmp/tmp-inst/            level      root,adm

$ sudo mkdir --mode 000 /var/tmp/tmp-inst

/var/tmp /var/tmp/tmp-inst/    level      root,adm

typeset -xr TMOUT=
        

declare -xr TMOUT=
        

$ sudo chmod o-w FILE
        

$ sudo mkdir /home/USER
        

$ sudo chgrp USER_GROUP /home/USER
        

$ sudo chmod 0740 /home/USER/.INIT_FILE
        

$ sudo chmod 0750 /home/USER
        

# ls -ld /home/USER
        

# chmod g-w /home/USER
# chmod o-rwx /home/USER
        

# echo $PATH

/etc/passwd

$ sudo chgrp USER_GROUP /home/USER/.INIT_FILE
        

$ sudo chown USER /home/USER/.*

$ sudo chgrp USER_GROUP /home/USER/FILE_DIR
        

$ sudo chown -R USER /home/USER
        

$ sudo chmod 0750 /home/USER/FILE_DIR
        

$ sudo chgrp root /boot/grub2/grub.cfg

$ sudo chgrp root /boot/grub2/user.cfg

$ sudo chown root /boot/grub2/grub.cfg 

$ sudo chown root /boot/grub2/user.cfg 

$ sed -i 's/\(set superusers=\).*/\1"<unique user ID>"/g' /etc/grub.d/01_users

grubby --update-kernel=ALL

# grub2-setpassword

$ sudo chmod 600 /boot/grub2/grub.cfg

$ sudo chmod 600 /boot/grub2/user.cfg

$ sudo chgrp root /boot/grub2/user.cfg

# grub2-setpassword

$ sudo chgrp root /boot/grub2/grub.cfg

$ sudo chown root /boot/grub2/grub.cfg 

$ sudo chown root /boot/grub2/user.cfg 

$ sudo chmod 700 /boot/grub2/grub.cfg

$ sudo chmod 600 /boot/grub2/user.cfg

cron.*                                                  /var/log/cron

cron.* action(type="omfile" file="/var/log/cron")

$ActionSendStreamDriverAuthMode x509/name

action(type="omfwd" Target="some.example.com" StreamDriverAuthMode="x509/name")

$ActionSendStreamDriverMode 1

action(type="omfwd" ... StreamDriverMode="1")

$DefaultNetstreamDriver gtls

global(DefaultNetstreamDriver="gtls")

$ ls -l LOGFILE
        

$ sudo chgrp root LOGFILE
        

$ ls -l LOGFILE
        

$ sudo chown root LOGFILE
        

$ ls -l LOGFILE
        

$ sudo chmod 640 LOGFILE
        

$ sudo systemctl enable systemd-journald.service

 $ sudo yum install logrotate

# rotate log files frequency
daily

$ sudo systemctl enable logrotate.timer

$ sudo yum install syslog-ng-core

$ sudo systemctl enable syslog-ng.service

$ModLoad imtcp
$InputTCPServerRun 514

$ModLoad imudp
$UDPServerRun 514

$ModLoad imtcp
$InputTCPServerRun port
$ModLoad imudp
$UDPServerRun port
$ModLoad imrelp
$InputRELPServerRun port
        

module(load="imtcp")
module(load="imudp")
input(type="imtcp" port="514")
input(type="imudp" port="514")

*.* @
        

*.* @@
        

*.* :omrelp:
        

echo 'action(type="omfwd" protocol="tcp" Target="<remote system>" port="6514"
    StreamDriver="gtls" StreamDriverMode="1" StreamDriverAuthMode="x509/name" streamdriver.CheckExtendedKeyPurpose="on")' >> /etc/rsyslog.conf

echo 'global(DefaultNetstreamDriverCAFile="/etc/pki/tls/cert.pem")' >> /etc/rsyslog.conf

• drop
  

  Any incoming network packets are dropped, there is no reply. Only outgoing network connections are possible.

• block
  

  Any incoming network connections are rejected with an icmp-host-prohibited message for IPv4 and icmp6-adm-prohibited for IPv6. Only network connections initiated from within the system are possible.

• public
  

  For use in public areas. You do not trust the other computers on the network to not harm your computer. Only selected incoming connections are accepted.

• external
  

  For use on external networks with masquerading enabled especially for routers. You do not trust the other computers on the network to not harm your computer. Only selected incoming connections are accepted.

• dmz
  

  For computers in your demilitarized zone that are publicly-accessible with limited access to your internal network. Only selected incoming connections are accepted.

• work
  

  For use in work areas. You mostly trust the other computers on networks to not harm your computer. Only selected incoming connections are accepted.

• home
  

  For use in home areas. You mostly trust the other computers on networks to not harm your computer. Only selected incoming connections are accepted.

• internal
  

  For use on internal networks. You mostly trust the other computers on the networks to not harm your computer. Only selected incoming connections are accepted.

• trusted
  

  All network connections are accepted.