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DISA STIG for Red Hat Enterprise Linux 9

Rules and Groups employed by this XCCDF Profile

  • Configure System to Forward All Mail From Postmaster to The Root Account

    Verify the administrators are notified in the event of an audit processing failure. Check that the "/etc/aliases" file has a defined value for "root". <pre>$ sudo grep "postmaster:\s*root$" /etc/al...
    Rule Medium Severity
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  • Configure Operating System to Protect Mail Server

    The guidance in this section is appropriate for any host which is operating as a site MTA, whether the mail server runs using Sendmail, Postfix, or some other software.
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  • Configure Postfix if Necessary

    Postfix stores its configuration files in the directory /etc/postfix by default. The primary configuration file is /etc/postfix/main.cf.
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  • Control Mail Relaying

    Postfix's mail relay controls are implemented with the help of the smtpd recipient restrictions option, which controls the restrictions placed on the SMTP dialogue once the sender and recipient env...
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  • Prevent Unrestricted Mail Relaying

    Modify the <pre>/etc/postfix/main.cf</pre> file to restrict client connections to the local network with the following command: <pre>$ sudo postconf -e 'smtpd_client_restrictions = permit_mynetwork...
    Rule Medium Severity
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  • NFS and RPC

    The Network File System is a popular distributed filesystem for the Unix environment, and is very widely deployed. This section discusses the circumstances under which it is possible to disable NF...
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  • Uninstall nfs-utils Package

    The nfs-utils package can be removed with the following command: 
    $ sudo dnf remove nfs-utils
    Rule Low Severity
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  • Configure NFS Clients

    The steps in this section are appropriate for systems which operate as NFS clients.
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  • Mount Remote Filesystems with Restrictive Options

    Edit the file <code>/etc/fstab</code>. For each filesystem whose type (column 3) is <code>nfs</code> or <code>nfs4</code>, add the text <code>,nodev,nosuid</code> to the list of mount options in co...
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  • Mount Remote Filesystems with nodev

    Add the nodev option to the fourth column of /etc/fstab for the line which controls mounting of any NFS mounts.
    Rule Medium Severity
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  • Mount Remote Filesystems with noexec

    Add the noexec option to the fourth column of /etc/fstab for the line which controls mounting of any NFS mounts.
    Rule Medium Severity
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  • Mount Remote Filesystems with nosuid

    Add the nosuid option to the fourth column of /etc/fstab for the line which controls mounting of any NFS mounts.
    Rule Medium Severity
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  • Network Time Protocol

    The Network Time Protocol is used to manage the system clock over a network. Computer clocks are not very accurate, so time will drift unpredictably on unmanaged systems. Central time protocols can...
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  • The Chrony package is installed

    System time should be synchronized between all systems in an environment. This is typically done by establishing an authoritative time server or set of servers and having all systems synchronize th...
    Rule Medium Severity
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  • The Chronyd service is enabled

    chrony is a daemon which implements the Network Time Protocol (NTP) is designed to synchronize system clocks across a variety of systems and use a source that is highly accurate. More information o...
    Rule Medium Severity
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  • Disable chrony daemon from acting as server

    The <code>port</code> option in <code>/etc/chrony.conf</code> can be set to <code>0</code> to make chrony daemon to never open any listening port for server operation and to operate strictly in a c...
    Rule Low Severity
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  • Disable network management of chrony daemon

    The cmdport option in /etc/chrony.conf can be set to 0 to stop chrony daemon from listening on the UDP port 323 for management connections made by chronyc.
    Rule Low Severity
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  • Configure Time Service Maxpoll Interval

    The <code>maxpoll</code> should be configured to <xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_time_service_set_maxpoll" use="legacy"></xccdf-1.2:sub> in <code>/etc/ntp.conf</code> o...
    Rule Medium Severity
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  • Ensure Chrony is only configured with the server directive

    Check that Chrony only has time sources configured with the server directive.
    Rule Medium Severity
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  • A remote time server for Chrony is configured

    <code>Chrony</code> is a daemon which implements the Network Time Protocol (NTP). It is designed to synchronize system clocks across a variety of systems and use a source that is highly accurate. M...
    Rule Medium Severity
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  • Obsolete Services

    This section discusses a number of network-visible services which have historically caused problems for system security, and for which disabling or severely limiting the service has been the best a...
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  • NIS

    The Network Information Service (NIS), also known as 'Yellow Pages' (YP), and its successor NIS+ have been made obsolete by Kerberos, LDAP, and other modern centralized authentication services. NIS...
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  • Uninstall ypserv Package

    The ypserv package can be removed with the following command: 
    $ sudo dnf remove ypserv
    Rule High Severity
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  • Rlogin, Rsh, and Rexec

    The Berkeley r-commands are legacy services which allow cleartext remote access and have an insecure trust model.
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  • Uninstall rsh-server Package

    The rsh-server package can be removed with the following command: 
    $ sudo dnf remove rsh-server
    Rule High Severity
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  • Remove Host-Based Authentication Files

    The <code>shosts.equiv</code> file lists remote hosts and users that are trusted by the local system. To remove these files, run the following command to delete them from any location: <pre>$ sudo ...
    Rule High Severity
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  • Remove User Host-Based Authentication Files

    The <code>~/.shosts</code> (in each user's home directory) files list remote hosts and users that are trusted by the local system. To remove these files, run the following command to delete them fr...
    Rule High Severity
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  • Telnet

    The telnet protocol does not provide confidentiality or integrity for information transmitted on the network. This includes authentication information such as passwords. Organizations which use tel...
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  • Uninstall telnet-server Package

    The telnet-server package can be removed with the following command: 
    $ sudo dnf remove telnet-server
    Rule High Severity
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  • TFTP Server

    TFTP is a lightweight version of the FTP protocol which has traditionally been used to configure networking equipment. However, TFTP provides little security, and modern versions of networking oper...
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  • Uninstall tftp-server Package

    The tftp-server package can be removed with the following command: 
     $ sudo dnf remove tftp-server
    Rule High Severity
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  • Network Routing

    A router is a very desirable target for a potential adversary because they fulfill a variety of infrastructure networking roles such as access to network segments, gateways to other networks, filt...
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  • Disable Quagga if Possible

    If Quagga was installed and activated, but the system does not need to act as a router, then it should be disabled and removed.
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  • Uninstall quagga Package

    The quagga package can be removed with the following command: 
     $ sudo dnf remove quagga
    Rule Low Severity
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  • SSH Server

    The SSH protocol is recommended for remote login and remote file transfer. SSH provides confidentiality and integrity for data exchanged between two systems, as well as server authentication, throu...
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  • Install OpenSSH client software

    The openssh-clients package can be installed with the following command: 
    $ sudo dnf install openssh-clients
    Rule Medium Severity
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  • Install the OpenSSH Server Package

    The openssh-server package should be installed. The openssh-server package can be installed with the following command: 
    $ sudo dnf install openssh-server
    Rule Medium Severity
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  • Enable the OpenSSH Service

    The SSH server service, sshd, is commonly needed. The sshd service can be enabled with the following command: 
    $ sudo systemctl enable sshd.service
    Rule Medium Severity
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  • Verify Group Who Owns SSH Server config file

    To properly set the group owner of /etc/ssh/sshd_config, run the command: 
    $ sudo chgrp root /etc/ssh/sshd_config
    Rule Medium Severity
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  • Verify Owner on SSH Server config file

    To properly set the owner of /etc/ssh/sshd_config, run the command: 
    $ sudo chown root /etc/ssh/sshd_config
    Rule Medium Severity
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  • Verify Permissions on SSH Server config file

    To properly set the permissions of /etc/ssh/sshd_config, run the command: 
    $ sudo chmod 0600 /etc/ssh/sshd_config
    Rule Medium Severity
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  • Verify Permissions on SSH Server Private *_key Key Files

    SSH server private keys - files that match the <code>/etc/ssh/*_key</code> glob, have to have restricted permissions. If those files are owned by the <code>root</code> user and the <code>root</code...
    Rule Medium Severity
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  • Verify Permissions on SSH Server Public *.pub Key Files

    To properly set the permissions of /etc/ssh/*.pub, run the command: 
    $ sudo chmod 0644 /etc/ssh/*.pub
    Rule Medium Severity
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  • Configure OpenSSH Client if Necessary

    The following configuration changes apply to the SSH client. They can improve security parameters relwevant to the client user, e.g. increasing entropy while generating initialization vectors. Note...
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  • Verify the SSH Private Key Files Have a Passcode

    When creating SSH key pairs, always use a passcode. <br> You can create such keys with the following command: <pre>$ sudo ssh-keygen -n [passphrase]</pre> Red Hat Enterprise Linux 9, for certificat...
    Rule Medium Severity
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  • Configure OpenSSH Server if Necessary

    If the system needs to act as an SSH server, then certain changes should be made to the OpenSSH daemon configuration file <code>/etc/ssh/sshd_config</code>. The following recommendations can be app...
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  • Set SSH Client Alive Count Max

    The SSH server sends at most <code>ClientAliveCountMax</code> messages during a SSH session and waits for a response from the SSH client. The option <code>ClientAliveInterval</code> configures time...
    Rule Medium Severity
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  • Set SSH Client Alive Interval

    SSH allows administrators to set a network responsiveness timeout interval. After this interval has passed, the unresponsive client will be automatically logged out. <br> <br> To set this t...
    Rule Medium Severity
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  • Disable Host-Based Authentication

    SSH's cryptographic host-based authentication is more secure than <code>.rhosts</code> authentication. However, it is not recommended that hosts unilaterally trust one another, even within an organ...
    Rule Medium Severity
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  • Enable SSH Server firewalld Firewall Exception

    If the SSH server is in use, inbound connections to SSH's port should be allowed to permit remote access through SSH. In more restrictive firewalld settings, the SSH port should be added to the pro...
    Rule Medium Severity
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The content of the drawer really is up to you. It could have form fields, definition lists, text lists, labels, charts, progress bars, etc. Spacing recommendation is 24px margins. You can put tabs in here, and can also make the drawer scrollable.

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