r4 - 2009-09-20 - 19:20:58 - DaveHartYou are here: NTP >  Dev Web > DevelopmentIssues > ConfigurationAndAuthorizationLevelsForNtpd
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-4.2.8p15 was released on 23 June 2020. It addresses 1 medium-severity security issue in ntpd, and provides 13 non-security bugfixes over 4.2.8p13.

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.

Configuration and Authorization Levels for ntpd

Background and History


BrianUtterback suggests we need to classify operations on data types as follows:

  • public-read-only
  • private-read-only
  • safe-write
  • unsafe-write


In the context of prior discussions, safe-write would be any ntpq/ntpdc operation that changes the ntpd state, such as ntpq -c ":config tos minsane 3" except those segregated as particularly dangerous, risking not just timekeeping but the system on which it runs, including:

ntpq -c "saveconfig /path/to/overwrite"
ntpq -c ":config logfile /path/to/appendfile"
ntpq -c ":config enable stats"
ntpq -c ":config filegen ..."

-- DaveHart - 16 Sep 2009

Do we need a table of ntpq and ntpdc directives and state which category they fall under?

-- HarlanStenn - 16 Sep 2009

ntp-dev-4.2.5p217 addresses these issues by disabling saveconfig by default unless there is a saveconfigdir configured in ntp.conf. Further, the following ntp.conf knobs are rejected from remote configuration:

enable stats
filegen (except filegen ... enable and disable)

-- DaveHart - 20 Sep 2009

Edit | WYSIWYG | Attach | Printable | Raw View | Backlinks: Web, All Webs | History: r5 < r4 < r3 < r2 < r1 | More topic actions...
SSL security by CAcert
Get the CAcert Root Certificate
This site is powered by the TWiki collaboration platform
IPv6 Ready
Copyright & 1999-2022 by the contributing authors. All material on this collaboration platform is the property of the contributing authors. Ideas, requests, problems regarding the site? Send feedback