r4 - 2011-03-29 - 15:50:34 - SteveKosteckeYou are here: NTP >  Support Web > ConfiguringAutokey > ConfiguringAutokeyDev
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.

Discussion of ConfiguringAutokey

ConfiguringAutokey was created to fill a need for an accurate step-by-step guide for setting up NTP Authentication using Autokey.

The information ipresented in ConfiguringAutokey was based on actual hands on testing of NTP Authentication after careful review of the Official NTP Authentication Documentation. This guide is not merely a compilation of existing information.

The information in ConfiguringAutokey was tested using various release versions of the NTP Reference Implementation, from both the stable and development tracks, on a variety of Linux and FreeBSD systems using different kernel versions.

-- SteveKostecke - 05 Dec 2005

Notes from Dr. Mills

The best advice is:

  1. Produce a working version of the configuration without Autokey.
  2. Roll keys for all group members using ntp-keygen with no options other than the -T option for the trusted hosts. Add the crypto command with no options to all configuration files. Add the autokey option to the server command for all clients of the trusted hosts. Verify the TC scheme works.
  3. Make the group keys with the -I option on a trusted host or trustedagent.
  4. Make the client keys from the group keys and distribute as in the original directions. Use an arbitray file name, preferably the name of the group.
  5. Add the ident option to the client server command with name the same as the client keys installed.
  6. For broadcast clients, use the same files, but use the ident option in the crypto command instead.

All this is in the autokey.html page along with a detailed description of the operations. Note also the relevant white pages at the NTP project page www.eecis.udel.edu/~ntp.html, especially the security analysis and the simulation and analysis of the on-wire protocol.

In contrast with the previous version, no options are required on the crypto command other than cited above. Note that the -s option is not required on the ntp-keygen program. These options can be added for special circumstances.


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