3.4.3.2.4 Ensure iptables firewall rules exist for all open ports

Information

Any ports that have been opened on non-loopback addresses need firewall rules to govern traffic.

Note:

- Changing firewall settings while connected over network can result in being locked out of the system
- Remediation will only affect the active system firewall, be sure to configure the default policy in your firewall management to apply on boot as well
- The remediation command opens up the port to traffic from all sources. Consult iptables documentation and set any restrictions in compliance with site policy

Without a firewall rule configured for open ports default firewall policy will drop all packets to these ports.

NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.

Solution

For each port identified in the audit which does not have a firewall rule establish a proper rule for accepting inbound connections:

# iptables -A INPUT -p <protocol> --dport <port> -m state --state NEW -j ACCEPT

See Also

https://workbench.cisecurity.org/benchmarks/13007

Item Details

Category: SECURITY ASSESSMENT AND AUTHORIZATION, SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|CA-9, 800-53|SC-7, 800-53|SC-7(5), CSCv7|9.4

Plugin: Unix

Control ID: 3052e4c11617052be2c894e708475405da31541a2edb295f7772d4051635e247