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host key backup

Posted Feb 23, 2010 7:10 UTC (Tue) by xoddam (subscriber, #2322)
In reply to: Trust, but verify by nix
Parent article: Trust, but verify

> 'if you reinstall your OS but keep the same IP address, you'll get this message on all the machines that connect to it'.

To save this happening again (and again ...)

Would it make sense to (remotely) backup the host key and restore it after the reinstallation?

There could well be something I'm missing...

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host key backup

Posted Feb 23, 2010 22:56 UTC (Tue) by nix (subscriber, #2304) [Link]

Yes, it would. But people don't always do that (often they don't even
realise what the host key is *for* until it's too late, and then, oops!).

More than once I've seen disaster-recovery hosts hotswapped into the place
of the machine they replace, IP address and all... but oops! they have a
different host key! Too late to fix, the original machine is dead now.
(Yes, this is a configuration error. But it's a pretty common one. More
common than not, I'd almost say.)