The SUSE operating system must not send Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirects.

From SLES 12 Security Technical Implementation Guide

Associated with: CCI-000366

SV-92195r3_rule The SUSE operating system must not send Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirects.

Vulnerability discussion

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.

Check content

Verify the SUSE operating system does not send IPv4 ICMP redirect messages. Check the value of the "all send_redirects" variables with the following command: # sysctl net.ipv4.conf.default.send_redirects net.ipv4.conf.default.send_redirects = 0 If the returned line does not have a value of "0” this is a finding.

Fix text

Configure the SUSE operating system to not allow interfaces to perform IPv4 ICMP redirects. Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" (or modify the line to have the required value): net.ipv4.conf.all.send_redirects=0 Run the following command to apply this value: # sysctl --system

Pro Tips

Lavender hyperlinks in small type off to the right (of CSS class id, if you view the page source) point to globally unique URIs for each document and item. Copy the link location and paste anywhere you need to talk unambiguously about these things.

You can obtain data about documents and items in other formats. Simply provide an HTTP header Accept: text/turtle or Accept: application/rdf+xml.