Re: DNS requests for 1918 space
On Tue, 16 Mar 2004 11:22:55 EST, Geo. [EMAIL PROTECTED] said: I'm aware of the issues involved with an ISP passing the requests on to the root servers but was looking specifically for security type issues relating to a private network passing the requests out to their ISP's dns servers. Hint: Every such DNS request that escapes will either time out or get an error. The admin is unwilling or unable to fix the resulting breakage. The fact that it isn't being fixed should tell you a lot about the site pgp0.pgp Description: PGP signature
Re: DNS requests for 1918 space
Geo. wrote: Can anyone point me at any papers that talk about security issues raised by private networks passing dns requests for RFC 1918 private address space out to their ISP's dns servers? I've never seen the whole paper on the topic. Leaking the fact that you use 10.10.10.0/24 or whatever internally is not a big deal. It's security by obscurity of the very weak kind. Anyone with half of a clue will drop traffic with a source or destination address of their internal RFC1918 networks at the border, (and even if one uses registered addresses internally, you would be dropping traffic with a souce address of the internal network from entering at the border). That's the real security. I'm aware of the issues involved with an ISP passing the requests on to the root servers but was looking specifically for security type issues relating to a private network passing the requests out to their ISP's dns servers. These requests will not go to the root servers any more than any other reverse lookups ISP's DNS, $ dig -x 10 ns ; DiG 8.3 -x ns ;; res options: init recurs defnam dnsrch ;; got answer: ;; -HEADER- opcode: QUERY, status: NOERROR, id: 2 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 2 ;; QUERY SECTION: ;; 10.in-addr.arpa, type = NS, class = IN ;; ANSWER SECTION: 10.in-addr.arpa.1W IN NSblackhole-1.iana.org. 10.in-addr.arpa.1W IN NSblackhole-2.iana.org. ;; ADDITIONAL SECTION: blackhole-1.iana.org. 16m43s IN A 192.175.48.6 blackhole-2.iana.org. 16m43s IN A 192.175.48.42 ;; Total query time: 53 msec ;; FROM: sec-tools.corp.globalstar.com to SERVER: default -- 207.88.152.10 ;; WHEN: Tue Mar 16 09:53:44 2004 The IN-ADDR.ARPA delegations for RFC1918 space are just like any other block. You'll just end up hitting IANA's blackhole servers, and not all that much, the cache times are one week. Of course, the obvious fix is to run your own internal DNS which is authorative for your RFC1918 addresses. -- Crist J. Clark [EMAIL PROTECTED] Globalstar Communications(408) 933-4387 The information contained in this e-mail message is confidential, intended only for the use of the individual or entity named above. If the reader of this e-mail is not the intended recipient, or the employee or agent responsible to deliver it to the intended recipient, you are hereby notified that any review, dissemination, distribution or copying of this communication is strictly prohibited. If you have received this e-mail in error, please contact [EMAIL PROTECTED]
Re: DNS requests for 1918 space
Can anyone point me at any papers that talk about security issues raised by private networks passing dns requests for RFC 1918 private address space out to their ISP's dns servers? I'm aware of the issues involved with an ISP passing the requests on to the root servers but was looking specifically for security type issues relating to a private network passing the requests out to their ISP's dns servers. Geo. http://www.nanog.org/mtg-0210/wessels.html has some very good information about some of the problems w/ leaked queries. http://as112.net/ has some mitigation stratagies. --bill
Re: DNS requests for 1918 space
On 16 Mar 2004, at 13:07, Crist Clark wrote: The IN-ADDR.ARPA delegations for RFC1918 space are just like any other block. You'll just end up hitting IANA's blackhole servers, and not all that much, the cache times are one week. Also, those blackhole servers are anycast, so they might even be answered relatively locally. See http://www.as112.net/. Of course, the obvious fix is to run your own internal DNS which is authorative for your RFC1918 addresses. Joe
Re: DNS requests for 1918 space
On 16.03 11:22, Geo. wrote: Can anyone point me at any papers that talk about security issues raised by private networks passing dns requests for RFC 1918 private address space out to their ISP's dns servers? RFC1918
Re: DNS requests for 1918 space
The IN-ADDR.ARPA delegations for RFC1918 space are just like any other block. You'll just end up hitting IANA's blackhole servers, and not all that much, the cache times are one week. In theory, yes. In reality there are quite a few resolvers that, apparently, do not receive the delegation response and continue to hit the roots with PTR queries for RFC1918 space. Recent measurements at a single instance of an anycasted root server show that at least 250 such resolvers generate between 60-120 RFC1918 PTR queries/sec. Duane W.
Re: DNS requests for 1918 space
On Tue, 16 Mar 2004 10:08:28 PST, bill said: http://www.nanog.org/mtg-0210/wessels.html has some very good information about some of the problems w/ leaked queries. http://as112.net/ has some mitigation stratagies. That mitigates the issue, but fails to deal with the root cause. One has to wonder - if a network is spewing enough broken DNS packets that it's noticable, and it's not getting fixed, what *else* is wrong with the network. Remember - every packet you see is a timeout happening back at the misconfigured site. It's like a car with one headlight out - yes, it still works, but whenever I see one on the road, I wonder what ELSE is marginal (like brake pads) pgp0.pgp Description: PGP signature
Re: DNS requests for 1918 space
Duane Wessels wrote: The IN-ADDR.ARPA delegations for RFC1918 space are just like any other block. You'll just end up hitting IANA's blackhole servers, and not all that much, the cache times are one week. In theory, yes. In reality there are quite a few resolvers that, apparently, do not receive the delegation response and continue to hit the roots with PTR queries for RFC1918 space. Is there something special about RFC1918 in this respect? Wouldn't these resolvers not work for all of the IN-ADDR.ARPA space? Wouldn't they be hitting the roots with all kinds of PTR queries? Recent measurements at a single instance of an anycasted root server show that at least 250 such resolvers generate between 60-120 RFC1918 PTR queries/sec. I assume (and no idea really if it is a good assumption or not) that the bulk of these broken resolvers do not belong to ISPs. The original recipient said specficially that he was using his ISP's nameservers. If he has broken resolvers, but the ISP servers are sane, he'll obviously end up pounding the ISP servers and perhaps the IANA blackhole servers if the queries are unique, but not the root servers. But yes there are plenty of broken resolvers out there. One of my current favorites is something in Novell print services that likes to do A queries on a single printer name several dozen times per second, wait a few seconds or minutes, then do a query storm on another printer name. These account for over 90% of the queries on some internal DNS servers. -- Crist J. Clark [EMAIL PROTECTED] Globalstar Communications(408) 933-4387
