mailing list archives
RE: IP announce DOS
From: "Burton Strauss" <BStrauss3 () comcast net>
Date: Fri, 10 Jun 2005 10:31:44 -0500
Addresses come in two kinds ...
If the address space was allocated TO YOU, either directly by a regional
registry (ARIN, RIPE, LACNIC, APNIC, AFRINIC, etc.) or by IANA, you have the
rights to move it.
If the address space was allocated to the ISP and subdivided, by them, then
you DO NOT own it and can not move it.
(Hence called portable and non-portable).
You can check the status of a block by doing a whois query (whois -h
whois.arin.net <address>) and you'll usually be able to figure it out from
$ nslookup www.skylist.net
$ whois -h whois.arin.net 18.104.22.168
[Redirected to rwhois.corenap.com:4321]
%rwhois V-1.5:003fff:00 cache02.ns.corenap.com (by Network Solutions, Inc.
network:Tech-Contact:hostmaster () corenap com
network:Updated-By:hostmaster () corenap com
If you look, you'll see that there are two blocks - a big one to Corenet and
a subnet to Skylist. If it were your space, portable, then you should only
see the single allocation (sometimes this is listed in the output as
'NetType: Direct Allocation'.
From: Thomas Ng [mailto:thomasng () ida gov sg]
Sent: Thursday, June 09, 2005 10:50 PM
To: 'Alex Thurlow'; security-basics () securityfocus com
Subject: RE: IP announce DOS
Shouldn't it be that each ISPs have their own big blocks? Chances are, the
class C given to you is in the middle of one of these huge blocks. I am not
sure what is your agreement with the old and new ISP, but I don't think it
is that simple to transfer the same set of IPs from one ISP to another. It
is technically possible ... but I don't think it is that simple.
Usually what I do when I change ISP is to just ask for a new set of IPs from
the new ISP, change the DNS, allow the TTLs to run out and shift to the new
sets of IP address. If you play with the DNS correctly, you can get minimal
downtime, dependent on size and sophistication of your network.
From: Alex Thurlow [mailto:buddychrist () gmail com]
Sent: Thursday, June 09, 2005 5:24 AM
To: 'security-basics () securityfocus com'
Subject: IP announce DOS
I'm not positive this is the correct list to ask, but it is a security
concern, so I thought I would. The company I work for had T1 lines
running to our office provided by a local provider. We had our own C
block of IPs being announced by them and routed to us over those T1s.
Our relationship with them went sour (for many reasons I won't get
here), and we had to move to a different provider. We had the routing
switched over to them. Everything was fine. Here it is a few weeks
later, and suddenly our old provider starts announcing these IPs
The end result is a partial DOS attack (hence writing to this list) as
some people can't reach us. They won't stop the announcement. I
know all the details on what they've said there as it's now gone to
executives and legal people dealing with them. Is there anything we
do here from a network standpoint? Someone we can report them to?
do people protect themselves from just anyone announcing IPs that
Thanks in advance,
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