I'm trying to rsync data between Amazon EC2 instances. This command works:

ssh -i path_to_key/key.pem user@machine1

This command does not:

rsync -e "ssh -i path_to_key/key.pem" user@machine1:/whatever ./
Address some_ip maps to some_amazonaws_domain_name, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!

What am I missing? Any way to fix that?

  • This warning should not prevent the command from working. Is it actually broken or you are just annoyed by the warning? If it is not working, try adding a -v to both rsync and ssh and posting the output here, like this: rsync -ve "ssh -vi path_to_key/key.pem" user@machine1:/whatever ./ – Aleksandar Ivanisevic Dec 29 '11 at 8:13
  • OMG, you are right, it really does work. I feel like an idiot. Assumed it wasn't working cause I had to fix the very same complain of ssh before. – clorz Dec 31 '11 at 23:45

Actually you are not missing anything, provided the path to the key is correct. The message you are seeing is because of the reverse lookup performed which will return aws domain name. It works like this, assuming that you are hosting abc.com on ip
lookup(abc.com) returns
but rev_lookup( will return some amazon domain.

This happened to some of the servers I was managing and I got it fixed by editing DNS records for reverse lookup. Try that.

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