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:

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_redirects=0
# sysctl -w net.ipv4.route.flush=1

See Also

https://workbench.cisecurity.org/benchmarks/8415

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b., CAT|II, CCI|CCI-000366, CSCv7|5.1, Rule-ID|SV-204616r603261_rule, Rule-ID|SV-204617r603261_rule, STIG-ID|RHEL-07-040650, STIG-ID|RHEL-07-040660, Vuln-ID|V-204616, Vuln-ID|V-204617

Plugin: Unix

Control ID: d3beb4bd793e4418ac0ec986ddc26573ea0043e89c96d6789714834fe35d9493