3.1.1 Ensure IP forwarding is disabled - sysctl net.ipv4.ip_forward = 0

Information

The net.ipv4.ip_forward and net.ipv6.conf.all.forwarding flags are used to tell the system whether it can forward packets or not.

Rationale:

Setting the flags to 0 ensures that a system with multiple interfaces (for example, a hard proxy), will never be able to forward packets, and therefore, never serve as a router.

Solution

Set the following parameter in /etc/sysctl.conf or a /etc/sysctl.d/* file:

net.ipv4.ip_forward = 0
net.ipv6.conf.all.forwarding = 0

Run the following commands to set the active kernel parameters:

# sysctl -w net.ipv4.ip_forward=0
# sysctl -w net.ipv6.conf.all.forwarding=0
# sysctl -w net.ipv4.route.flush=1
# sysctl -w net.ipv6.route.flush=1

Notes:

This Benchmark recommendation maps to:

Red Hat Enterprise Linux 7 Security Technical Implementation Guide:

Version 2, Release: 3 Benchmark Date: 26 Apr 2019



Vul ID: V-72309

Rule ID: SV-86933r2_rule

STIG ID: RHEL-07-040740

Severity: CAT II

See Also

https://workbench.cisecurity.org/files/2688

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6, CSCv7|5.1

Plugin: Unix

Control ID: ac08da90ec4cba1ce14fbb691c45f1a0bb5161be48c2693da2a2ba5a14fd832d