From Red Hat Enterprise Linux 7 Security Technical Implementation Guide
Part of SRG-OS-000480-GPOS-00227
Associated with: CCI-000366
If the systems access control program is not configured with appropriate rules for allowing and denying access to system network resources, services may be accessible to unauthorized hosts.
If the "firewalld" package is not installed, ask the System Administrator (SA) if another firewall application (such as iptables) is installed. If an application firewall is not installed, this is a finding. Verify the system's access control program is configured to grant or deny system access to specific hosts. Check to see if "firewalld" is active with the following command: # systemctl status firewalld firewalld.service - firewalld - dynamic firewall daemon Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled) Active: active (running) since Sun 2014-04-20 14:06:46 BST; 30s ago If "firewalld" is active, check to see if it is configured to grant or deny access to specific hosts or services with the following commands: # firewall-cmd --get-default-zone public # firewall-cmd --list-all --zone=public public (default, active) interfaces: eth0 sources: services: mdns ssh ports: masquerade: no forward-ports: icmp-blocks: rich rules: rule family="ipv4" source address="92.188.21.1/24" accept rule family="ipv4" source address="211.17.142.46/32" accept If "firewalld" is not active, determine whether "tcpwrappers" is being used by checking whether the "hosts.allow" and "hosts.deny" files are empty with the following commands: # ls -al /etc/hosts.allow rw-r----- 1 root root 9 Aug 2 23:13 /etc/hosts.allow # ls -al /etc/hosts.deny -rw-r----- 1 root root 9 Apr 9 2007 /etc/hosts.deny If "firewalld" and "tcpwrappers" are not installed, configured, and active, ask the SA if another access control program (such as iptables) is installed and active. Ask the SA to show that the running configuration grants or denies access to specific hosts or services. If "firewalld" is active and is not configured to grant access to specific hosts or "tcpwrappers" is not configured to grant or deny access to specific hosts, this is a finding.
If "firewalld" is installed and active on the system, configure rules for allowing specific services and hosts. If "firewalld" is not "active", enable "tcpwrappers" by configuring "/etc/hosts.allow" and "/etc/hosts.deny" to allow or deny access to specific hosts.
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