Can outsiders identify a machine with 2 IP addresses?

Not really as far as I know. Given the 2 IP's they will know that they both are on linodes and both are in the same datacenter. If you have reverse DNS set up right (and you probably will if they're sending email), then they could look at registrations for DNS and guess. That's it though.

> I ask because I am interested in setting up a mailing list server separate from my main site, so as not to risk the spam rating of the main site. Is it necessary for these services to be split on completely different machines?

You shouldn't worry about that at all. I'd be much more worried about neighbors on your netblock spamming which can get the whole network on blacklists.

OK, thanks for the quick answer.

The only thing they can find out is that linode owns both ips

OK, that is great to know. Thanks for that!

Chris

@bd3521:

The only thing they can find out is that linode owns both ips

False!!!!!

ssh-keyscan is your friend….

That of course assumes you have ssh running on both addresses which is easy to fix..

Yeah, there are a lot of ways depending on what services you have running and configuration of those services. For instance, most mail servers will by default attach to all IPs and it give out your real hostname.