linux-formula/metadata/service/system/cis/cis-3-1-2.yml

# 3.1.2 Ensure packet redirect sending is disabled
#
# Description
# ===========
# ICMP Redirects are used to send routing information to other hosts. As a host
# itself does not act as a router (in a host only configuration), there is
# no need to send redirects.
#
# Rationale
# =========
# An attacker could use a compromised host to send invalid ICMP redirects to
# other router devices in an attempt to corrupt routing and have users access
# a system set up by the attacker as opposed to a valid system.
#
# Audit
# =====
#
# Run the following commands and verify output matches:
#
#   # sysctl net.ipv4.conf.all.send_redirects
#   net.ipv4.conf.all.send_redirects = 0
#   # sysctl net.ipv4.conf.default.send_redirects
#   net.ipv4.conf.default.send_redirects = 0
#
# Remediation
# ===========
#
# Set the following parameters in the /etc/sysctl.conf file:
#
#   net.ipv4.conf.all.send_redirects = 0
#   net.ipv4.conf.default.send_redirects = 0
#
# Run the following commands to set the active kernel parameters:
#
#   # sysctl -w net.ipv4.conf.all.send_redirects=0
#   # sysctl -w net.ipv4.conf.default.send_red

parameters:
  linux:
    system:
      kernel:
        sysctl:
          net.ipv4.conf.all.send_redirects: 0
          net.ipv4.conf.default.send_redirects: 0