From SUSE Linux Enterprise Server v11 for System z Security Technical Implementation Guide
Part of GEN003602
Associated with: CCI-001551
The processing of (ICMP) timestamp requests increases the attack surface of the system.
Verify the system does not respond to ICMP TIMESTAMP_REQUESTs Procedure: # iptables -L INPUT | grep "timestamp" This should return the following entries for "timestamp-reply" and "timestamp_request": DROP icmp -- anywhere anywhere icmp timestamp-request DROP icmp -- anywhere anywhere icmp timestamp-reply If either does not exist or does not "DROP" the message, this is a finding.
Configure the system to not respond to ICMP TIMESTAMP_REQUESTs. This is done by rejecting ICMP type 13 and 14 messages at the firewall. Procedure: 1. Check the SuSEfirewall2 configuration to see if custom rules are being used: # grep -v '^#' /etc/sysconfig/SuSEfirewall2 | grep FW_CUSTOMRULES If the command returns FW_CUSTOMRULES=”” then no custom rules are being used. In that case edit the /etc/sysconfig/SuSEfirewall2 file and use the vendor supplied file by setting FW_CUSTOMRULES="/etc/sysconfig/scripts/SuSEfirewall2-custom" 2. Edit the file defined by the FW_CUSTOMRULES variable and add these commands to append the INPUT chain: iptables -A INPUT -p ICMP --icmp-type timestamp-request -j DROP iptables -A INPUT -p ICMP --icmp-type timestamp-reply -j DROP Restart the firewall: # rcSuSEfirewall2 restart
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.
Powered by sagemincer