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.

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Are you using Autokey in production? If so, please contact Harlan - he's got some questions for you.

5.1. NTP Access Policy

It was proposed on news://comp.protocols.time.ntp to publish the access policy for ntp via ntp/tcp. Since ntp (the time protocol) only uses ntp/udp, ntp/tcp is available as a reserved port number for ntp.

It would be possible to publish both a machine readable version (in some standard format, to be determined) and a human readable version.

A simple solution is to use inetd to offer a file on connection to ntp/tcp. Example line in inetd.conf:

ntp  stream  tcp     nowait  nobody  /usr/libexec/tcpd       /bin/cat /etc/ntp-access-policy.txt

The file /etc/ntp-access-policy.txt would then contain the access policy.

-- KoosVanDenHout - 28 Aug 2003