NTP users are strongly urged to take immediate action to ensure that their NTP daemons are not susceptible to being used in distributed denial-of-service (DDoS) attacks. Please also take this opportunity to defeat denial-of-service attacks by implementing Ingress and Egress filtering through BCP38.
ntp-4.2.8p12
was released on 14 August 2018. It addresses 1 low-/medium-severity security issue in ntpd, 1 low-severity security issue in ntpq and ntpdc, and provides 27 non-security bugfixes and 4 other improvements over 4.2.8p11.
Please see the NTP Security Notice for vulnerability and mitigation details.Are you using Autokey in production? If so, please contact Harlan - he's got some questions for you.
noepeer
behavior.
ntpd
can be vulnerable to Sybil attacks. If a system is set up to use a trustedkey and if one is not using the feature introduced in ntp-4.2.8p6 allowing an optional 4th field in the ntp.keys
file to specify which IPs can serve time, a malicious authenticated peer -- i.e. one where the attacker knows the private symmetric key -- can create arbitrarily-many ephemeral associations in order to win the clock selection of ntpd
and modify a victim's clock. Two additional protections are offered in ntp-4.2.8p11. One is the noepeer
directive, which disables symmetric passive ephemeral peering. The other extends the functionality of the 4th field in the ntp.keys
file to include specifying a subnet range.
noepeer
directive to prohibit symmetric passive ephemeral associations.
ippeerlimit
directive to limit the number of peer associations from an IP.
ntpd
instances.
noepeer
processing was reported by Martin Burnicki of Meinberg.