# 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