Guide to the Secure Configuration of Red Hat Enterprise Linux 9
Rules, Groups, and Values defined within the XCCDF Benchmark
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Network Related Kernel Runtime Parameters for Hosts and Routers
Certain kernel parameters should be set for systems which are acting as either hosts or routers to improve the system's ability defend against cert...Group -
net.ipv4.conf.all.accept_redirects
Disable ICMP Redirect AcceptanceValue -
net.ipv4.conf.all.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.ipv4.conf.default.arp_filter
Controls whether the ARP filter is enabled or not. 1 - Allows you to have multiple network interfaces on the same subnet, and have the ARPs for ea...Value -
net.ipv4.conf.default.arp_ignore
Control the response modes for ARP queries that resolve local target IP addresses: 0 - (default): reply for any local target IP address, configure...Value -
net.ipv4.conf.all.forwarding
Toggle IPv4 ForwardingValue -
net.ipv4.conf.all.log_martians
Disable so you don't Log Spoofed Packets, Source Routed Packets, Redirect PacketsValue -
net.ipv4.conf.all.rp_filter
Enable to enforce sanity checking, also called ingress filtering or egress filtering. The point is to drop a packet if the source and destination I...Value -
net.ipv4.conf.all.secure_redirects
Enable to prevent hijacking of routing path by only allowing redirects from gateways known in routing table. Disable to refuse acceptance of secure...Value -
net.ipv4.conf.all.shared_media
Controls whether the system can send (router) or accept (host) RFC1620 shared media redirects. <code>shared_media</code> for the interface will be ...Value -
net.ipv4.conf.default.accept_redirects
Disable ICMP Redirect Acceptance?Value -
net.ipv4.conf.default.accept_source_route
Disable IP source routing?Value -
net.ipv4.conf.default.log_martians
Disable so you don't Log Spoofed Packets, Source Routed Packets, Redirect PacketsValue -
Disable Accepting Packets Routed Between Local Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.accept_local</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net...Rule Medium Severity -
Disable Accepting ICMP Redirects for All IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.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 IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.accept_source_route</code> kernel parameter, run the following command: <pre>$ sudo sysctl...Rule Medium Severity -
Configure ARP filtering for All IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.arp_filter</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.i...Rule Medium Severity -
Configure Response Mode of ARP Requests for All IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.arp_ignore</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.i...Rule Medium Severity -
Drop Gratuitious ARP frames on All IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.drop_gratuitous_arp</code> kernel parameter, run the following command: <pre>$ sudo sysctl...Rule Medium Severity -
Disable Kernel Parameter for IPv4 Forwarding on all IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.forwarding</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.i...Rule Medium Severity -
Enable Kernel Parameter to Log Martian Packets on all IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.log_martians</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net...Rule Unknown Severity -
Disable ATM Support
The Asynchronous Transfer Mode (ATM) is a protocol operating on network, data link, and physical layers, based on virtual circuits and virtual path...Rule Medium Severity -
Prevent Routing External Traffic to Local Loopback on All IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.route_localnet</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w n...Rule Medium Severity -
Enable Kernel Parameter to Use Reverse Path Filtering on all IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.rp_filter</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ip...Rule Medium Severity -
Disable Kernel Parameter for Accepting Secure ICMP Redirects on all IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.secure_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w...Rule Medium Severity -
Configure Sending and Accepting Shared Media Redirects for All IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.shared_media</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net...Rule Medium Severity -
Disable Kernel Parameter for Accepting ICMP Redirects by Default on IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.default.accept_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysct...Rule Medium Severity -
Disable Kernel Parameter for Accepting Source-Routed Packets on IPv4 Interfaces by Default
To set the runtime status of the <code>net.ipv4.conf.default.accept_source_route</code> kernel parameter, run the following command: <pre>$ sudo sy...Rule Medium Severity -
Enable Kernel Paremeter to Log Martian Packets on all IPv4 Interfaces by Default
To set the runtime status of the <code>net.ipv4.conf.default.log_martians</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w...Rule Unknown Severity -
Enable Kernel Parameter to Use Reverse Path Filtering on all IPv4 Interfaces by Default
To set the runtime status of the <code>net.ipv4.conf.default.rp_filter</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w ne...Rule Medium Severity -
dbadm_read_user_files SELinux Boolean
default - Default SELinux boolean setting.
on - SELinux boolean is enabled.
off - SELinux boolean is disabled.Value -
Configure Kernel Parameter for Accepting Secure Redirects By Default
To set the runtime status of the <code>net.ipv4.conf.default.secure_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysct...Rule Medium Severity -
Configure Sending and Accepting Shared Media Redirects by Default
To set the runtime status of the <code>net.ipv4.conf.default.shared_media</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w...Rule Medium Severity -
Enable Kernel Parameter to Ignore ICMP Broadcast Echo Requests on IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.icmp_echo_ignore_broadcasts</code> kernel parameter, run the following command: <pre>$ sudo sysctl ...Rule Medium Severity -
Enable Kernel Parameter to Ignore Bogus ICMP Error Responses on IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.icmp_ignore_bogus_error_responses</code> kernel parameter, run the following command: <pre>$ sudo s...Rule Unknown Severity -
Set Kernel Parameter to Increase Local Port Range
To set the runtime status of the <code>net.ipv4.ip_local_port_range</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.i...Rule Medium Severity -
Configure Kernel to Rate Limit Sending of Duplicate TCP Acknowledgments
Make sure that the system is configured to limit the maximal rate for sending duplicate acknowledgments in response to incoming TCP packets that ar...Rule Medium Severity -
Enable Kernel Parameter to Use TCP RFC 1337 on IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.tcp_rfc1337</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.tcp_...Rule Medium Severity -
Enable Kernel Parameter to Use TCP Syncookies on Network Interfaces
To set the runtime status of the <code>net.ipv4.tcp_syncookies</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.t...Rule Medium Severity -
Disable Kernel Parameter for Sending ICMP Redirects on all IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.send_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w n...Rule Medium Severity -
Disable Kernel Parameter for Sending ICMP Redirects on all IPv4 Interfaces by Default
To set the runtime status of the <code>net.ipv4.conf.default.send_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysctl ...Rule Medium Severity -
Disable Kernel Parameter for IP Forwarding on IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.ip_forward</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.ip_fo...Rule Medium Severity -
nftables
<code>If firewalld or iptables are being used in your environment, please follow the guidance in their respective section and pass-over the guidanc...Group -
Nftables Base Chain Hooks
The possible hooks which can be used to configure the base chain are: <code>ingress</code> (only in netdev family since Linux kernel 4.2, and inet ...Value -
Nftables Chain Names
The rules in nftables are attached to chains. Unlike in iptables, there are no predefined chains like INPUT, OUTPUT, etc. Instead, to filter pack...Value -
Nftables Base Chain Policies
This is the default verdict that will be applied to packets reaching the end of the chain (i.e, no more rules to be evaluated against). Currently ...Value -
Nftables Base Chain Priorities
Each nftables base chain is assigned a priority that defines its ordering among other base chains, flowtables, and Netfilter internal operations a...Value -
Disable CAN Support
The Controller Area Network (CAN) is a serial communications protocol which was initially developed for automotive and is now also used in marine, ...Rule Medium Severity -
Nftables Base Chain Types
Base chains are those that are registered into the Netfilter hooks, i.e. these chains see packets flowing through the Linux TCP/IP stack. The poss...Value -
Nftables Families
Netfilter enables filtering at multiple networking levels. With iptables there is a separate tool for each level: iptables, ip6tables, arptables, ...Value
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