3.1.2 Ensure packet redirect sending is disabled - 'sysctl net.ipv4.conf.default.send_redirects'

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 the /etc/sysctl.conf file: net.ipv4.conf.all.send_redirects = 0net.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/files/1866

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7(12), CSCv6|11

Plugin: Unix

Control ID: b2f66dfd0abc438bc7e26d7a564e8eece8a4617e27dbcb17854abb99639f883b