The system must not send IPv4 Internet Control Message Protocol (ICMP) redirects.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-22417	GEN003610	SV-37629r1_rule	ECSC-1	Medium

Description
ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages contain information from the system's route table possibly revealing portions of the network topology.

STIG	Date
Red Hat Enterprise Linux 5 Security Technical Implementation Guide	2017-03-01

Details

Check Text ( C-36828r1_chk )
Verify the system does not send IPv4 ICMP redirect messages. # grep [01] /proc/sys/net/ipv4/conf/*/send_redirects|egrep "default|all" If all of the resulting lines do not end with "0", this is a finding.

Fix Text (F-31666r1_fix)
Configure the system to not send IPv4 ICMP redirect messages. Edit /etc/sysctl.conf and add a setting for "net.ipv4.conf.all.send_redirects=0" and "net.ipv4.conf.default.send_redirects=0". # sysctl -p