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Guide to the Secure Configuration of Debian 12

Rules, Groups, and Values defined within the XCCDF Benchmark

  • FTP Server

    FTP is a common method for allowing remote access to files. Like telnet, the FTP protocol is unencrypted, which means that passwords and other data...
    Group
  • Configure Firewalls to Protect the FTP Server

    By default, <code>iptables</code> blocks access to the ports used by the web server. To configure <code>iptables</code> to allow port 21 traffic, ...
    Rule Unknown Severity
  • Mail Server Software

    Mail servers are used to send and receive email over the network. Mail is a very common service, and Mail Transfer Agents (MTAs) are obvious target...
    Group
  • Uninstall Sendmail Package

    Sendmail is not the default mail transfer agent and is not installed by default. The <code>sendmail</code> package can be removed with the followin...
    Rule Medium Severity
  • Disable Postfix Network Listening

    Edit the file <code>/etc/postfix/main.cf</code> to ensure that only the following <code>inet_interfaces</code> line appears: <pre>inet_interfaces =...
    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
  • 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
  • Chrony Configure Pool and Server

    <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
  • Verify Group Who Owns /etc/chrony.keys File

    To properly set the group owner of /etc/chrony.keys, run the command:
    $ sudo chgrp root /etc/chrony.keys
    Rule Medium Severity
  • Verify User Who Owns /etc/chrony.keys File

    To properly set the owner of /etc/chrony.keys, run the command:
    $ sudo chown root /etc/chrony.keys 
    Rule Medium Severity
  • Verify Permissions On /etc/chrony.keys File

    To properly set the permissions of /etc/chrony.keys, run the command:
    $ sudo chmod 0600 /etc/chrony.keys
    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
  • Uninstall xinetd Package

    The xinetd package can be removed with the following command:
    $ apt-get remove xinetd
    Rule Low Severity
  • Remove NIS Client

    The Network Information Service (NIS), formerly known as Yellow Pages, is a client-server directory service protocol used to distribute system conf...
    Rule Unknown Severity
  • Uninstall ypserv Package

    The ypserv package can be removed with the following command:
    $ apt-get remove ypserv
    Rule High Severity
  • Uninstall rsh-server Package

    The rsh-server package can be removed with the following command:
    $ apt-get remove rsh-server
    Rule High Severity
  • Uninstall rsh Package

    The rsh package contains the client commands for the rsh services
    Rule Unknown 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
  • Uninstall talk-server Package

    The talk-server package can be removed with the following command:
     $ apt-get remove 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
  • Uninstall telnet-server Package

    The telnet-server package can be removed with the following command:
    $ apt-get remove 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
  • Uninstall tftp-server Package

    The tftp-server package can be removed with the following command:
     $ apt-get remove tftp-server
    Rule High Severity
  • 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
  • Uninstall net-snmp Package

    The <code>snmp</code> package provides the snmpd service. The <code>snmp</code> package can be removed with the following command: <pre> $ apt-get...
    Rule Unknown Severity
  • 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
  • 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
  • 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
  • Remove the OpenSSH Server Package

    The <code>openssh-server</code> package should be removed. The <code>openssh-server</code> package can be removed with the following command: <pre>...
    Rule Medium Severity
  • 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
  • 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
  • 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
  • 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
  • Remove SSH Server iptables Firewall exception (Unusual)

    By default, inbound connections to SSH's port are allowed. If the SSH server is not being used, this exception should be removed from the firewall ...
    Rule Unknown Severity
  • 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 automat...
    Rule Medium Severity
  • 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 un...
    Rule Medium Severity
  • Disable Compression Or Set Compression to delayed

    Compression is useful for slow network connections over long distances but can cause performance issues on local LANs. If use of compression is req...
    Rule Medium Severity
  • Disable SSH Access via Empty Passwords

    Disallow SSH login with empty passwords. The default SSH configuration disables logins with empty passwords. The appropriate configuration is used ...
    Rule High Severity
  • Disable GSSAPI Authentication

    Unless needed, SSH should not permit extraneous or unnecessary authentication mechanisms like GSSAPI. <br> The default SSH configuration disallows ...
    Rule Medium Severity
  • Disable Kerberos Authentication

    Unless needed, SSH should not permit extraneous or unnecessary authentication mechanisms like Kerberos. <br> The default SSH configuration disallow...
    Rule Medium Severity
  • Disable PubkeyAuthentication Authentication

    Unless needed, SSH should not permit extraneous or unnecessary authentication mechanisms. To disable PubkeyAuthentication authentication, add or co...
    Rule Medium Severity
  • Disable SSH Support for .rhosts Files

    SSH can emulate the behavior of the obsolete rsh command in allowing users to enable insecure access to their accounts via <code>.rhosts</code> fil...
    Rule Medium Severity
  • Disable SSH Support for Rhosts RSA Authentication

    SSH can allow authentication through the obsolete rsh command through the use of the authenticating user's SSH keys. This should be disabled. <br> ...
    Rule Medium Severity
  • Disable SSH Root Login

    The root user should never be allowed to login to a system directly over a network. To disable root login via SSH, add or correct the following lin...
    Rule Medium Severity
  • Disable X11 Forwarding

    The X11Forwarding parameter provides the ability to tunnel X11 traffic through the connection to enable remote graphic connections. SSH has the cap...
    Rule Medium Severity
  • Do Not Allow SSH Environment Options

    Ensure that users are not able to override environment variables of the SSH daemon. <br> The default SSH configuration disables environment process...
    Rule Medium Severity
  • Enable GSSAPI Authentication

    Sites setup to use Kerberos or other GSSAPI Authenticaion require setting sshd to accept this authentication. To enable GSSAPI authentication, add ...
    Rule Medium Severity
  • Enable PAM

    UsePAM Enables the Pluggable Authentication Module interface. If set to “yes” this will enable PAM authentication using ChallengeResponseAuthentica...
    Rule Medium Severity
  • Enable Public Key Authentication

    Enable SSH login with public keys. <br> The default SSH configuration enables authentication based on public keys. The appropriate configuration is...
    Rule Medium Severity
  • Enable Use of Strict Mode Checking

    SSHs <code>StrictModes</code> option checks file and ownership permissions in the user's home directory <code>.ssh</code> folder before accepting l...
    Rule Medium Severity

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