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Guide to the Secure Configuration of Ubuntu 18.04

Rules, Groups, and Values defined within the XCCDF Benchmark

  • 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 ...
    Rule Medium Severity
  • Enable the NTP Daemon

    The ntp service can be enabled with the following command:
    $ sudo systemctl enable ntp.service
    Rule High Severity
  • Enable systemd_timesyncd Service

    The systemd_timesyncd service can be enabled with the following command:
    $ sudo systemctl enable systemd_timesyncd.service
    Rule High 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
  • 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
  • SSH RekeyLimit - size

    Specify the size component of the rekey limit.
    Value
  • SSH RekeyLimit - size

    Specify the size component of the rekey limit.
    Value
  • SSH Compression Setting

    Specify the compression setting for SSH connections.
    Value
  • 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
  • Chat/Messaging Services

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

    The telnet protocol does not provide confidentiality or integrity for information transmitted on the network. This includes authentication informat...
    Group
  • 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
  • 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
  • Remote Authentication Dial-In User Service (RADIUS)

    Remote Authentication Dial-In User Service (RADIUS) is a networking protocol, operating on port 1812 that provides centralized Authentication, Auth...
    Group
  • Hardware RNG Entropy Gatherer Daemon

    The rngd feeds random data from hardware device to kernel random device.
    Group
  • 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 ...
    Group
  • 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.
    Group
  • Samba(SMB) Microsoft Windows File Sharing Server

    When properly configured, the Samba service allows Linux systems to provide file and print sharing to Microsoft Windows systems. There are two soft...
    Group
  • Configure Samba if Necessary

    All settings for the Samba daemon can be found in <code>/etc/samba/smb.conf</code>. Settings are divided between a <code>[global]</code> configurat...
    Group
  • SSH Privilege Separation Setting

    Specify whether and how sshd separates privileges when handling incoming network connections.
    Value
  • SSH LoginGraceTime setting

    Configure parameters for how long the servers stays connected before the user has successfully logged in
    Value
  • SSH MaxStartups setting

    Configure parameters for maximum concurrent unauthenticated connections to the SSH daemon.
    Value
  • Restrict Printer Sharing

    By default, Samba utilizes the CUPS printing service to enable printer sharing with Microsoft Windows workstations. If there are no printers on the...
    Group
  • Restrict SMB File Sharing to Configured Networks

    Only users with local user accounts will be able to log in to Samba shares by default. Shares can be limited to particular users or network address...
    Group
  • Disable Samba if Possible

    Even after the Samba server package has been installed, it will remain disabled. Do not enable this service unless it is absolutely necessary to pr...
    Group
  • SNMP Server

    The Simple Network Management Protocol allows administrators to monitor the state of network devices, including computers. Older versions of SNMP w...
    Group
  • Disable SNMP Server if Possible

    The system includes an SNMP daemon that allows for its remote monitoring, though it not installed by default. If it was installed and activated but...
    Group
  • Configure SNMP Server if Necessary

    If it is necessary to run the snmpd agent on the system, some best practices should be followed to minimize the security risk from the installation...
    Group
  • SNMP read-only community string

    Specify the SNMP community string used for read-only access.
    Value
  • SNMP read-write community string

    Specify the SNMP community string used for read-write access.
    Value
  • SSH Server

    The SSH protocol is recommended for remote login and remote file transfer. SSH provides confidentiality and integrity for data exchanged between tw...
    Group
  • SSH enabled firewalld zone

    Specify firewalld zone to enable SSH service. This value is used only for remediation purposes.
    Value
  • SSH Approved ciphers by FIPS

    Specify the FIPS approved ciphers that are used for data integrity protection by the SSH server.
    Value
  • SSH Approved MACs by FIPS

    Specify the FIPS approved MACs (message authentication code) algorithms that are used for data integrity protection by the SSH server.
    Value
  • SSH session Idle time

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

    Specify port the SSH server is listening.
    Value
  • SSH Max authentication attempts

    Specify the maximum number of authentication attempts per connection.
    Value
  • SSH is required to be installed

    Specify if the Policy requires SSH to be installed. Used by SSH Rules to determine if SSH should be uninstalled or configured.<br> A value of 0 mea...
    Value
  • SSH Strong KEX by FIPS

    Specify the FIPS approved KEXs (Key Exchange Algorithms) algorithms that are used for methods in cryptography by which cryptographic keys are exch...
    Value
  • SSH Max Sessions Count

    Specify the maximum number of open sessions permitted.
    Value
  • SSH Max Keep Alive Count

    Specify the maximum number of idle message counts before session is terminated.
    Value
  • Install the OpenSSH Server Package

    The <code>openssh-server</code> package should be installed. The <code>openssh-server</code> package can be installed with the following command: <...
    Rule Medium Severity

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