Guide to the Secure Configuration of Oracle Linux 9
Rules, Groups, and Values defined within the XCCDF Benchmark
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net.ipv4.conf.default.log_martians
Disable so you don't Log Spoofed Packets, Source Routed Packets, Redirect PacketsValue -
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 -w net.ipv4.conf.all.accept_source_route=0</pre> ...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.ipv4.conf.all.arp_filter=<xccdf-1.2:sub idref="xccd...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 -w net.ipv4.conf.all.drop_gratuitous_arp=1</pre> ...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.ipv4.conf.all.log_martians=1</pre> To make sure t...Rule Unknown 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 net.ipv4.conf.all.route_localnet=0</pre> To make su...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 net.ipv4.conf.all.secure_redirects=0</pre> To mak...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 sysctl -w net.ipv4.conf.default.accept_redirects=0</pre...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 sysctl -w net.ipv4.conf.default.accept_source_route=...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 net.ipv4.conf.default.log_martians=1</pre> To mak...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 net.ipv4.conf.default.rp_filter=1</pre> To make sure...Rule Medium Severity -
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 sysctl -w net.ipv4.conf.default.secure_redirects=0</pre...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 -w net.ipv4.icmp_echo_ignore_broadcasts=1</pre> To...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 sysctl -w net.ipv4.icmp_ignore_bogus_error_response...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.ipv4.ip_local_port_range=32768 65535</pre> To make ...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_rfc1337=1</pre> To make sure that the setting is p...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.tcp_syncookies=1</pre> To make sure that the settin...Rule Medium Severity -
Network Parameters for Hosts Only
If the system is not going to be used as a router, then setting certain kernel parameters ensure that the host will not perform routing of network traffic.Group -
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_forward=0</pre> To make sure that the setting is per...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 guidance in this section.</code><br><br> nftables is a su...Group -
Uncomplicated Firewall (ufw)
The Linux kernel in Ubuntu provides a packet filtering system called netfilter, and the traditional interface for manipulating netfilter are the iptables suite of commands. iptables provide a compl...Group -
Uncommon Network Protocols
The system includes support for several network protocols which are not commonly used. Although security vulnerabilities in kernel networking code are not frequently discovered, the consequences ca...Group -
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, industrial, and medical applications. To configur...Rule Medium Severity -
Disable IEEE 1394 (FireWire) Support
The IEEE 1394 (FireWire) is a serial bus standard for high-speed real-time communication. To configure the system to prevent the <code>firewire-core</code> kernel module from being loaded, add the...Rule Low Severity -
Disable TIPC Support
The Transparent Inter-Process Communication (TIPC) protocol is designed to provide communications between nodes in a cluster. To configure the system to prevent the <code>tipc</code> kernel module...Rule Low Severity -
Disable Wireless Through Software Configuration
If it is impossible to remove the wireless hardware from the device in question, disable as much of it as possible through software. The following methods can disable software support for wireless ...Group -
Disable Bluetooth Kernel Module
The kernel's module loading system can be configured to prevent loading of the Bluetooth module. Add the following to the appropriate <code>/etc/modprobe.d</code> configuration file to prevent the ...Rule Medium Severity -
Deactivate Wireless Network Interfaces
Deactivating wireless network interfaces should prevent normal usage of the wireless capability. <br> <br> Configure the system to disable all wireless network interfaces with the followi...Rule Medium Severity -
File Permissions and Masks
Traditional Unix security relies heavily on file and directory permissions to prevent unauthorized users from reading or modifying files to which they should not have access. <br> <br> Severa...Group -
Verify Permissions on Important Files and Directories
Permissions for many files on a system must be set restrictively to ensure sensitive information is properly protected. This section discusses important permission restrictions which can be verifie...Group -
Ensure All World-Writable Directories Are Owned by root User
All directories in local partitions which are world-writable should be owned by root. If any world-writable directories are not owned by root, this should be investigated. Following this, the files...Rule Medium Severity -
Verify Permissions on /etc/audit/rules.d/*.rules
To properly set the permissions of/etc/audit/rules.d/*.rules, run the command:$ sudo chmod 0640 /etc/audit/rules.d/*.rules
Rule Medium Severity -
Ensure All SGID Executables Are Authorized
The SGID (set group id) bit should be set only on files that were installed via authorized means. A straightforward means of identifying unauthorized SGID files is determine if any were not install...Rule Medium Severity -
Ensure All SUID Executables Are Authorized
The SUID (set user id) bit should be set only on files that were installed via authorized means. A straightforward means of identifying unauthorized SUID files is determine if any were not installe...Rule Medium Severity -
Verify Permissions on Files with Local Account Information and Credentials
The default restrictive permissions for files which act as important security databases such as <code>passwd</code>, <code>shadow</code>, <code>group</code>, and <code>gshadow</code> files must be ...Group -
Verify Group Who Owns gshadow File
To properly set the group owner of/etc/gshadow, run the command:$ sudo chgrp root /etc/gshadow
Rule Medium Severity -
Verify Group Who Owns passwd File
To properly set the group owner of/etc/passwd, run the command:$ sudo chgrp root /etc/passwd
Rule Medium Severity -
Verify Group Who Owns shadow File
To properly set the group owner of/etc/shadow, run the command:$ sudo chgrp root /etc/shadow
Rule Medium Severity -
Verify User Who Owns Backup group File
To properly set the owner of/etc/group-, run the command:$ sudo chown root /etc/group-
Rule Medium Severity -
Verify User Who Owns Backup gshadow File
To properly set the owner of/etc/gshadow-, run the command:$ sudo chown root /etc/gshadow-
Rule Medium Severity -
Verify User Who Owns Backup passwd File
To properly set the owner of/etc/passwd-, run the command:$ sudo chown root /etc/passwd-
Rule Medium Severity -
Verify Group Who Owns Backup shadow File
To properly set the owner of/etc/shadow-, run the command:$ sudo chown root /etc/shadow-
Rule Medium Severity -
Verify User Who Owns group File
To properly set the owner of/etc/group, run the command:$ sudo chown root /etc/group
Rule Medium Severity -
Verify User Who Owns gshadow File
To properly set the owner of/etc/gshadow, run the command:$ sudo chown root /etc/gshadow
Rule Medium Severity -
Verify User Who Owns passwd File
To properly set the owner of/etc/passwd, run the command:$ sudo chown root /etc/passwd
Rule Medium Severity -
Verify User Who Owns shadow File
To properly set the owner of/etc/shadow, run the command:$ sudo chown root /etc/shadow
Rule Medium Severity -
Verify Permissions on Backup group File
To properly set the permissions of/etc/group-, run the command:$ sudo chmod 0644 /etc/group-
Rule Medium Severity -
Verify Permissions on Backup gshadow File
To properly set the permissions of/etc/gshadow-, run the command:$ sudo chmod 0000 /etc/gshadow-
Rule Medium Severity -
Verify Permissions on Backup passwd File
To properly set the permissions of/etc/passwd-, run the command:$ sudo chmod 0644 /etc/passwd-
Rule Medium Severity -
Verify Permissions on Backup shadow File
To properly set the permissions of/etc/shadow-, run the command:$ sudo chmod 0000 /etc/shadow-
Rule Medium Severity
Node 2
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