If an organization registered an address they are responsible for keeping the contact name up to date. If they don't announce the route, they have not provided a valid contact, and there is no way to contact them, including publishing a list on major mailing lists, then it should be safe to recover the address since every reasonable effort was made to contact them. If a route is not announced, this is a NOOP anyway.
Things get out of date very, very quickly on the net (and real-life). And even the best run organizations sometimes have lapses. How about an example a little closer to home. Although its an AS number rather than an IP network number, what happens when the net runs out of AS numbers. Should things like AS 690 'reclaimed' based on out-of-date information? Although Elise is kind enough to forward messages on to ANS now, what if she got tired of it, and just dumped the message in the bit bucket. And the following week the NIC issued AS 690 to some other network. $ whois as 690 Merit Computer Network (ASN-NSFNET-T3-RT) 1075 Beal Avenue Ann Arbor, MI 48109 Autonomous System Name: NSFNET-T3-RT-AS Autonomous System Number: 690 Coordinator: Gerich, Elise (EG14) epg@MERIT.EDU 313 764 9430 (FAX) (313) 747-3745 Record last updated on 13-Apr-94. The InterNIC Registration Services Host contains ONLY Internet Information (Networks, ASN's, Domains, and POC's). Please use the whois server at nic.ddn.mil for MILNET Information.
If the route is announced, go through the AS path and/or traceroute asking the provider closest to the route for a contact name. Just send a "Dear IP Provider" letter stating "This appears to be your customer but we have no way to contact them. Can you help?". Most providers have a way of contacting their customers.
Sometimes not even the providers seems to know. I've dealt with several providers whose only contact information for a customer is a credit card number. They 'contact' the customer by disabling the connection, and what for the customer to call them. Not very friendly, and about as bad as hijacking the connection. Ok, maybe that's just the little guys. If you consider MFS as the 'provider' of MAE-East. You might expect MFS knew how to contact their mae-east customers. Sorry MFS, you're just a nice neutral example to show the half-life of contact information on the net is very, very short. I've been contacting other ISP's on mae-east off and on for several months. About 40% of MFS's mae-east customer contact information was outdated or non-existent. For example, the contact person doesn't work for the company any more. The company has changed names three or more times, moved twice, and no one knows the current company name, address or phone number. In a few cases, the phone number has been disconnected, with no forwarding number. Add the number of people who got the message, and didn't care to respond, I can easily understand a 60% non-response rate. -- Sean Donelan, Data Research Associates, Inc, St. Louis, MO Affiliation given for identification not representation