Guide to the Secure Configuration of Alibaba Cloud Linux 2
Rules, Groups, and Values defined within the XCCDF Benchmark
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net.ipv4.icmp_ignore_bogus_error_responses
Enable to prevent unnecessary loggingValue -
net.ipv4.tcp_invalid_ratelimit
Configure the maximal rate for sending duplicate acknowledgments in response to incoming invalid TCP packets.Value -
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 -
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 -
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 -
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 -
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 -
Verify Group Who Owns Backup passwd File
To properly set the group owner of/etc/passwd-, run the command:$ sudo chgrp root /etc/passwd-
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 -
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 -
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 ...Group -
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 -
cron_userdomain_transition SELinux Boolean
default - Default SELinux boolean setting.
on - SELinux boolean is enabled.
off - SELinux boolean is disabled.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 -
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 -
Nftables Master configuration file
The file which contains top level configuration for nftables service, and with which, the service is started.Value -
Nftables Tables
Tables in nftables hold chains. Each table only has one address family and only applies to packets of this family. Tables can have one of six fami...Value -
SuSEfirewall2
The SuSEfirewall2 provides a managed firewall.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 ip...Group -
Verify ufw Enabled
Theufwservice can be enabled with the following command:$ sudo systemctl enable ufw.service
Rule Medium Severity -
Uncommon Network Protocols
The system includes support for several network protocols which are not commonly used. Although security vulnerabilities in kernel networking code ...Group -
Disable DCCP Support
The Datagram Congestion Control Protocol (DCCP) is a relatively new transport layer protocol, designed to support streaming media and telephony. T...Rule Medium Severity -
Disable SCTP Support
The Stream Control Transmission Protocol (SCTP) is a transport layer protocol, designed to support the idea of message-oriented communication, with...Rule Medium Severity -
Wireless Networking
Wireless networking, such as 802.11 (WiFi) and Bluetooth, can present a security risk to sensitive or classified systems and networks. Wireless net...Group -
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 ...Group -
Disable Unused Interfaces
Network interfaces expand the attack surface of the system. Unused interfaces are not monitored or controlled, and should be disabled. <br><br> If...Group -
Transport Layer Security Support
Support for Transport Layer Security (TLS), and its predecessor, the Secure Sockets Layer (SSL), is included in Red Hat Enterprise Linux in the Ope...Group -
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 t...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 impo...Group -
cups_execmem SELinux Boolean
default - Default SELinux boolean setting.
on - SELinux boolean is enabled.
off - SELinux boolean is disabled.Value -
cvs_read_shadow SELinux Boolean
default - Default SELinux boolean setting.
on - SELinux boolean is enabled.
off - SELinux boolean is disabled.Value -
Verify that local System.map file (if exists) is readable only by root
Files containing sensitive informations should be protected by restrictive permissions. Most of the time, there is no need that these files need ...Rule Unknown Severity -
Ensure All Files Are Owned by a User
If any files are not owned by a user, then the cause of their lack of ownership should be investigated. Following this, the files should be deleted...Rule Medium Severity -
Enable Kernel Parameter to Enforce DAC on Hardlinks
To set the runtime status of the <code>fs.protected_hardlinks</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w fs.protecte...Rule Medium Severity -
Enable Kernel Parameter to Enforce DAC on Symlinks
To set the runtime status of the <code>fs.protected_symlinks</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w fs.protected...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>gro...Group
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