3.2.2 Ensure packet redirect sending is disabled

Information

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.

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.

Solution

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

Example:

# printf "
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
" >> /etc/sysctl.d/60-netipv4_sysctl.conf

Run the following command to set the active kernel parameters:

# (
sysctl -w net.ipv4.conf.all.send_redirects=0
sysctl -w net.ipv4.conf.default.send_redirects=0
sysctl -w net.ipv4.route.flush=1
}

See Also

https://workbench.cisecurity.org/files/3742

Item Details

Category: CONFIGURATION MANAGEMENT, SYSTEM AND SERVICES ACQUISITION

References: 800-53|CM-2, 800-53|CM-6, 800-53|CM-7, 800-53|CM-7(1), 800-53|CM-9, 800-53|SA-3, 800-53|SA-8, 800-53|SA-10, CSCv7|5.1

Plugin: Unix

Control ID: 12c653f8127bfdb8648210607cdde981ea857ed452de4143adc3ce466b6ef62a