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Guide to the Secure Configuration of Oracle Linux 9

Rules, Groups, and Values defined within the XCCDF Benchmark

  • 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
  • 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
  • Configure NFS Servers

    The steps in this section are appropriate for systems which operate as NFS servers.
    Group
  • Ensure All-Squashing Disabled On All Exports

    The <code>all_squash</code> maps all uids and gids to an anonymous user. This should be disabled by removing any instances of the <code>all_squash<...
    Rule Low Severity
  • Use Kerberos Security on All Exports

    Using Kerberos on all exported mounts prevents a malicious client or user from impersonating a system user. To cryptography authenticate users to t...
    Rule Medium Severity
  • Configure the Exports File Restrictively

    Linux's NFS implementation uses the file <code>/etc/exports</code> to control what filesystems and directories may be accessed via NFS. (See the <c...
    Group
  • Export Filesystems Read-Only if Possible

    If a filesystem is being exported so that users can view the files in a convenient fashion, but there is no need for users to edit those files, exp...
    Group
  • Use Access Lists to Enforce Authorization Restrictions

    When configuring NFS exports, ensure that each export line in <code>/etc/exports</code> contains a list of hosts which are allowed to access that e...
    Group
  • Vendor Approved Time Servers

    The list of vendor-approved time servers
    Value
  • Reboot Required

    A system reboot is implicitly required after some actions in order to complete the reconfiguration of the system. In many cases, the changes will n...
    Group
  • 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 se...
    Rule Medium Severity
  • Install the ntp service

    The ntpd service should be installed.
    Rule High Severity
  • Enable the NTP Daemon

    The ntpd service can be enabled with the following command:
    $ sudo systemctl enable ntpd.service
    Rule Medium Severity
  • 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 f...
    Rule Low Severity
  • Disable network management of chrony daemon

    The <code>cmdport</code> option in <code>/etc/chrony.conf</code> can be set to <code>0</code> to stop chrony daemon from listening on the UDP port ...
    Rule Low Severity
  • 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...
    Rule Medium Severity
  • Ensure Chrony is only configured with the server directive

    Check that Chrony only has time sources configured with the server directive.
    Rule Medium Severity
  • 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 s...
    Rule Medium Severity
  • Obsolete Services

    This section discusses a number of network-visible services which have historically caused problems for system security, and for which disabling or...
    Group
  • Xinetd

    The <code>xinetd</code> service acts as a dedicated listener for some network services (mostly, obsolete ones) and can be used to provide access co...
    Group
  • Uninstall xinetd Package

    The xinetd package can be removed with the following command:
    $ sudo yum erase xinetd
    Rule Low Severity
  • Disable xinetd Service

    The xinetd service can be disabled with the following command:
    $ sudo systemctl mask --now xinetd.service
    Rule Medium Severity
  • NIS

    The Network Information Service (NIS), also known as 'Yellow Pages' (YP), and its successor NIS+ have been made obsolete by Kerberos, LDAP, and oth...
    Group
  • Rlogin, Rsh, and Rexec

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

    The rsh-server package can be removed with the following command:
    $ sudo yum erase rsh-server
    Rule High Severity
  • Uninstall rsh Package

    The rsh package contains the client commands for the rsh services
    Rule Unknown Severity
  • Disable rlogin Service

    The <code>rlogin</code> service, which is available with the <code>rsh-server</code> package and runs as a service through xinetd or separately as ...
    Rule High Severity
  • Uninstall tftp-server Package

    The tftp-server package can be removed with the following command:
     $ sudo yum erase tftp-server
    Rule High Severity
  • 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 comm...
    Rule High Severity
  • Remove Rsh Trust Files

    The files <code>/etc/hosts.equiv</code> and <code>~/.rhosts</code> (in each user's home directory) list remote hosts and users that are trusted by ...
    Rule High Severity
  • 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 ...
    Rule High Severity
  • Chat/Messaging Services

    The talk software makes it possible for users to send and receive messages across systems through a terminal session.
    Group
  • Uninstall talk-server Package

    The talk-server package can be removed with the following command:
     $ sudo yum erase talk-server
    Rule Medium Severity
  • Uninstall talk Package

    The <code>talk</code> package contains the client program for the Internet talk protocol, which allows the user to chat with other users on differe...
    Rule Medium Severity
  • Telnet

    The telnet protocol does not provide confidentiality or integrity for information transmitted on the network. This includes authentication informat...
    Group
  • Uninstall telnet-server Package

    The telnet-server package can be removed with the following command:
    $ sudo yum erase telnet-server
    Rule High Severity
  • Remove telnet Clients

    The telnet client allows users to start connections to other systems via the telnet protocol.
    Rule Low Severity
  • Disable telnet Service

    Make sure that the activation of the <code>telnet</code> service on system boot is disabled. The <code>telnet</code> socket can be disabled with t...
    Rule High Severity
  • TFTP Server

    TFTP is a lightweight version of the FTP protocol which has traditionally been used to configure networking equipment. However, TFTP provides littl...
    Group
  • TFTP server secure directory

    Specify the directory which is used by TFTP server as a root directory when running in secure mode.
    Value
  • Remove tftp Daemon

    Trivial File Transfer Protocol (TFTP) is a simple file transfer protocol, typically used to automatically transfer configuration or boot files betw...
    Rule Low Severity
  • SSH session Idle time

    Specify duration of allowed idle time.
    Value
  • SSH Server Listening Port

    Specify port the SSH server is listening.
    Value
  • Ensure tftp Daemon Uses Secure Mode

    If running the Trivial File Transfer Protocol (TFTP) service is necessary, it should be configured to change its root directory at startup. To do s...
    Rule Medium Severity
  • Print Support

    The Common Unix Printing System (CUPS) service provides both local and network printing support. A system running the CUPS service can accept print...
    Group
  • Configure the CUPS Service if Necessary

    CUPS provides the ability to easily share local printers with other systems over the network. It does this by allowing systems to share lists of av...
    Group
  • Proxy Server

    A proxy server is a very desirable target for a potential adversary because much (or all) sensitive data for a given infrastructure may flow throug...
    Group
  • Disable Squid if Possible

    If Squid was installed and activated, but the system does not need to act as a proxy server, then it should be disabled and removed.
    Group
  • Uninstall squid Package

    The squid package can be removed with the following command:
     $ sudo yum erase squid
    Rule Unknown Severity
  • Disable Squid

    The squid service can be disabled with the following command:
    $ sudo systemctl mask --now squid.service
    Rule Unknown Severity

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