Understanding Neighborcast

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This article gives a quick overview of the Neighborcast feature in the F-Secure Automatic Update Agent (AUA), and also provides detailed information on its download logic.

Neighborcast is configured via three options:
  • Neighborcast client (enabled/disabled) - controls whether the client tries to locate updates from clients in the same LAN.
  • Neighborcast server (enabled/disabled) - controls whether the client listens and responds to neighborcast queries and offers updates for download.
  • Neighborcast port - port used for neighborcast UDP queries.
When neighborcast is enabled, the client
  • gets a list of available updates from Policy Manager Server (PMS)/Automatic Update Server (AUS)
  • makes the decision to download an update
  • sends a neighborcast query via broadcast UDP packet over the configured neighborcast port
  • receives a unicast UDP reply back from other clients having the update
  • picks a suitable peer and sends it a unicast UDP 'open session'
  • after a positive confirmation, proceeds to download files over HTTP directly from the selected peer
  • after downloading all the files, terminates the neighborcast session
  • checks the received files against MD5 hashes and downloads any missing or corrupted files from PMS/AUS.
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