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Author Topic: Dyndns  (Read 1916 times)


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« on: January 31, 2019, 03:54:10 AM »

I already have good working v4 DynDns service for
How do I get hurricane to just do a lookup for and re-establish the tunnel?
I didn't see my use case in setup docs so did I miss something?


  • Sr. Network Engineer, Hurricane Electric
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Re: Dyndns
« Reply #1 on: January 31, 2019, 04:34:31 AM »

If we didn't know what the IP was, the process for a tunnel would wind up looking something like this at creation:
- Resolve hostname to IP
 - Resolution failure: Disallow tunnel creation, or leave existing IP/TTL alone if already created.
 - Hostname resolves
 - Did IP change?
  - Yes: Update tunnel IP
  - No: Wait TTL seconds and repeat cycle.

Now, this doesn't look too bad, until you look at the ultimate scenario system-wide, with sub-60s TTLs and over 70,000 tunnels to do this on.  Most of those IPs not changing for weeks or longer.  Lots of extra processing on our side for limited gain.  You'd also be down for the duration of the TTL regardless of when your IP changed.  By triggering it from your side, it's as close to effective at the time of the IP change as is possible.