Guide to the Secure Configuration of Red Hat Enterprise Linux 8
Rules, Groups, and Values defined within the XCCDF Benchmark
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net.ipv4.tcp_invalid_ratelimit
Configure the maximal rate for sending duplicate acknowledgments in response to incoming invalid TCP packets.Value -
Remove iptables-services Package
Theiptables-services
package can be removed with the following command:$ sudo yum erase iptables-services
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 -
Configure the Firewalld Ports
Configure the <code>firewalld</code> ports to allow approved services to have access to the system. To configure <code>firewalld</code> to open por...Rule Medium Severity -
Firewalld Must Employ a Deny-all, Allow-by-exception Policy for Allowing Connections to Other Systems
Red Hat Enterprise Linux 8 incorporates the "firewalld" daemon, which allows for many different configurations. One of these configurations is zone...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 -
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 -
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-services Package
Theiptables-services
package can be installed with the following command:$ sudo yum install iptables-services
Rule Medium Severity -
Install iptables Package
Theiptables
package can be installed with the following command:$ sudo yum install iptables
Rule Medium Severity -
net.ipv4.tcp_rfc1337
Enable to enable TCP behavior conformant with RFC 1337Value -
net.ipv4.tcp_syncookies
Enable to turn on TCP SYN Cookie ProtectionValue -
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
Theip6tables
service can be enabled with the following command:$ sudo systemctl enable ip6tables.service
Rule Medium Severity -
Verify iptables Enabled
Theiptables
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 -
Ensure ip6tables 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 -
Ensure iptables 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 iptables 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 -
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 -
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 -
IPV6_AUTOCONF
Toggle global IPv6 auto-configuration (only, if global forwarding is disabled)Value -
net.ipv6.conf.all.accept_ra_defrtr
Accept default router in router advertisements?Value -
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 Interface Usage of IPv6
To disable interface usage of IPv6, add or correct the following lines in <code>/etc/sysconfig/network</code>: <pre>NETWORKING_IPV6=no IPV6INIT=no<...Rule Unknown Severity -
Disable Support for RPC IPv6
RPC services for NFSv4 try to load transport modules for <code>udp6</code> and <code>tcp6</code> by default, even if IPv6 has been disabled in <cod...Rule Unknown 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 -
net.ipv6.conf.all.accept_ra_pinfo
Accept prefix information in router advertisements?Value -
Use Privacy Extensions for Address
To introduce randomness into the automatic generation of IPv6 addresses, add or correct the following line in <code>/etc/sysconfig/network-scripts/...Rule Unknown Severity -
Manually Assign Global IPv6 Address
To manually assign an IP address for an interface, edit the file <code>/etc/sysconfig/network-scripts/ifcfg-<i>interface</i></code>. Add or correct...Rule Unknown Severity -
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 -
Disable Accepting ICMP Redirects for All IPv6 Interfaces
To set the runtime status of the <code>net.ipv6.conf.all.accept_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w...Rule Medium Severity -
Disable Kernel Parameter for Accepting Source-Routed Packets on all IPv6 Interfaces
To set the runtime status of the <code>net.ipv6.conf.all.accept_source_route</code> kernel parameter, run the following command: <pre>$ sudo sysctl...Rule Medium Severity -
Configure Auto Configuration on All IPv6 Interfaces
To set the runtime status of the <code>net.ipv6.conf.all.autoconf</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv...Rule Unknown Severity -
Disable Kernel Parameter for IPv6 Forwarding
To set the runtime status of the <code>net.ipv6.conf.all.forwarding</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.i...Rule Medium Severity -
Configure Maximum Number of Autoconfigured Addresses on All IPv6 Interfaces
To set the runtime status of the <code>net.ipv6.conf.all.max_addresses</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w ne...Rule Unknown Severity
Node 2
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