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Guide to the Secure Configuration of SUSE Linux Enterprise 15

Rules, Groups, and Values defined within the XCCDF Benchmark

  • Set Default iptables Policy for Forwarded Packets

    To set the default policy to DROP (instead of ACCEPT) for the built-in FORWARD chain which processes packets that will be forwarded from one interf...
    Rule Medium Severity
  • Rsyslog Logs Sent To Remote Host

    If system logs are to be useful in detecting malicious activities, it is necessary to send logs to a remote server. An intruder who has compromised...
    Group
  • Remote Log Server

    Specify an URI or IP address of a remote host where the log messages will be sent and stored.
    Value
  • Ensure Logs Sent To Remote Host

    To configure rsyslog to send logs to a remote log server, open <code>/etc/rsyslog.conf</code> and read and understand the last section of the file,...
    Rule Medium Severity
  • Configure TLS for rsyslog remote logging

    Configure <code>rsyslog</code> to use Transport Layer Security (TLS) support for logging to remote server for the Forwarding Output Module in <code...
    Rule Medium Severity
  • Configure CA certificate for rsyslog remote logging

    Configure CA certificate for <code>rsyslog</code> logging to remote server using Transport Layer Security (TLS) using correct path for the <code>De...
    Rule Medium Severity
  • Network Configuration and Firewalls

    Most systems must be connected to a network of some sort, and this brings with it the substantial risk of network attack. This section discusses th...
    Group
  • Ensure System is Not Acting as a Network Sniffer

    The system should not be acting as a network sniffer, which can capture all traffic on the network to which it is connected. Run the following to d...
    Rule Medium Severity
  • firewalld

    The dynamic firewall daemon <code>firewalld</code> provides a dynamically managed firewall with support for network “zones” to assign a level of tr...
    Group
  • Ensure Unnecessary Services and Ports Are Not Accepted

    Services and ports can be accepted or explicitly rejected or dropped by a zone. For every zone, a default behavior can be set that handles incoming...
    Rule Medium Severity
  • Inspect and Activate Default firewalld Rules

    Firewalls can be used to separate networks into different zones based on the level of trust the user has decided to place on the devices and traffi...
    Group
  • Install firewalld Package

    The firewalld package can be installed with the following command:
    $ sudo zypper install firewalld
    Rule Medium Severity
  • Verify firewalld Enabled

    The firewalld service can be enabled with the following command:
    $ sudo systemctl enable firewalld.service
    Rule Medium Severity
  • Strengthen the Default Ruleset

    The default rules can be strengthened. The system scripts that activate the firewall rules expect them to be defined in configuration files under t...
    Group
  • Ensure firewall rules exist for all open ports

    Any ports that have been opened on non-loopback addresses need firewall rules to govern traffic.
    Rule Medium Severity
  • Set Default firewalld Zone for Incoming Packets

    To set the default zone to <code>drop</code> for the built-in default zone which processes incoming IPv4 and IPv6 packets, modify the following lin...
    Rule Medium Severity
  • IPSec Support

    Support for Internet Protocol Security (IPsec) is provided with Libreswan.
    Group
  • Install libreswan Package

    The libreswan package provides an implementation of IPsec and IKE, which permits the creation of secure tunnels over untrusted networks. The <code>...
    Rule Medium Severity
  • Install strongswan Package

    The Strongswan package provides an implementation of IPsec and IKE, which permits the creation of secure tunnels over untrusted networks. The <code...
    Rule Medium Severity
  • Verify Any Configured IPSec Tunnel Connections

    Libreswan provides an implementation of IPsec and IKE, which permits the creation of secure tunnels over untrusted networks. As such, IPsec can be ...
    Rule Medium Severity
  • Ensure Outbound and Established Connections are Configured

    Configure the firewall rules for new outbound and established connections.
    Rule Medium Severity
  • iptables and ip6tables

    A host-based firewall called <code>netfilter</code> is included as part of the Linux kernel distributed with the system. It is activated by default...
    Group
  • Install iptables Package

    The iptables package can be installed with the following command:
    $ sudo zypper install iptables
    Rule Medium Severity
  • Ensure iptables are flushed

    nftables is a replacement for iptables, ip6tables, ebtables and arptables
    Rule Medium Severity
  • Inspect and Activate Default Rules

    View the currently-enforced <code>iptables</code> rules by running the command: <pre>$ sudo iptables -nL --line-numbers</pre> The command is analog...
    Group
  • Verify ip6tables Enabled if Using IPv6

    The ip6tables service can be enabled with the following command:
    $ sudo systemctl enable ip6tables.service
    Rule Medium Severity
  • Verify iptables Enabled

    The iptables service can be enabled with the following command:
    $ sudo systemctl enable iptables.service
    Rule Medium Severity
  • Set Default ip6tables Policy for Incoming Packets

    To set the default policy to DROP (instead of ACCEPT) for the built-in INPUT chain which processes incoming packets, add or correct the following l...
    Rule Medium Severity
  • Set configuration for IPv6 loopback traffic

    Configure the loopback interface to accept traffic. Configure all other interfaces to deny traffic to the loopback network.
    Rule Medium Severity
  • Set configuration for loopback traffic

    Configure the loopback interface to accept traffic. Configure all other interfaces to deny traffic to the loopback network.
    Rule Medium Severity
  • Strengthen the Default Ruleset

    The default rules can be strengthened. The system scripts that activate the firewall rules expect them to be defined in the configuration files <co...
    Group
  • Restrict ICMP Message Types

    In <code>/etc/sysconfig/iptables</code>, the accepted ICMP messages types can be restricted. To accept only ICMP echo reply, destination unreachabl...
    Group
  • Log and Drop Packets with Suspicious Source Addresses

    Packets with non-routable source addresses should be rejected, as they may indicate spoofing. Because the modified policy will reject non-matching ...
    Group
  • IPv6

    The system includes support for Internet Protocol version 6. A major and often-mentioned improvement over IPv4 is its enormous increase in the numb...
    Group
  • Disable Support for IPv6 Unless Needed

    Despite configuration that suggests support for IPv6 has been disabled, link-local IPv6 address auto-configuration occurs even when only an IPv4 ad...
    Group
  • Ensure IPv6 is disabled through kernel boot parameter

    To disable IPv6 protocol support in the Linux kernel, add the argument <code>ipv6.disable=1</code> to the default GRUB2 command line for the Linux ...
    Rule Low Severity
  • Disable IPv6 Networking Support Automatic Loading

    To prevent the IPv6 kernel module (<code>ipv6</code>) from binding to the IPv6 networking stack, add the following line to <code>/etc/modprobe.d/di...
    Rule Medium Severity
  • Disable IPv6 Addressing on All IPv6 Interfaces

    To disable support for (<code>ipv6</code>) addressing on all interface add the following line to <code>/etc/sysctl.d/ipv6.conf</code> (or another f...
    Rule Medium Severity
  • Disable IPv6 Addressing on IPv6 Interfaces by Default

    To disable support for (<code>ipv6</code>) addressing on interfaces by default add the following line to <code>/etc/sysctl.d/ipv6.conf</code> (or a...
    Rule Medium Severity
  • Configure IPv6 Settings if Necessary

    A major feature of IPv6 is the extent to which systems implementing it can automatically configure their networking devices using information from ...
    Group
  • IPV6_AUTOCONF

    Toggle global IPv6 auto-configuration (only, if global forwarding is disabled)
    Value
  • net.ipv6.conf.default.accept_source_route

    Trackers could be using source-routed packets to generate traffic that seems to be intra-net, but actually was created outside and has been redirec...
    Value
  • net.ipv6.conf.default.autoconf

    Enable auto configuration on IPv6 interfaces
    Value
  • net.ipv6.conf.default.forwarding

    Toggle IPv6 default Forwarding
    Value
  • net.ipv6.conf.default.max_addresses

    Maximum number of autoconfigured IPv6 addresses
    Value
  • net.ipv6.conf.default.router_solicitations

    Accept all router solicitations by default?
    Value
  • Configure Accepting Router Advertisements on All IPv6 Interfaces

    To set the runtime status of the <code>net.ipv6.conf.all.accept_ra</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ip...
    Rule Medium Severity
  • Configure Accepting Default Router in Router Advertisements on All IPv6 Interfaces

    To set the runtime status of the <code>net.ipv6.conf.all.accept_ra_defrtr</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w...
    Rule Unknown Severity
  • Configure Accepting Prefix Information in Router Advertisements on All IPv6 Interfaces

    To set the runtime status of the <code>net.ipv6.conf.all.accept_ra_pinfo</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w ...
    Rule Unknown Severity
  • Configure Accepting Router Preference in Router Advertisements on All IPv6 Interfaces

    To set the runtime status of the <code>net.ipv6.conf.all.accept_ra_rtr_pref</code> kernel parameter, run the following command: <pre>$ sudo sysctl ...
    Rule Unknown Severity

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