July 2003 - Test - lists.nanog.org

Cisco Vulnerability (updated?)
by Jason Frisvold 23 Jul '03

23 Jul '03

Apparently protocol 103 does not need to have a ttl of 0 or 1 when it hits the interface in order to cause the DoS ... Cisco has updated their advisory to reflect this (Version 1.9 now).. Just wanted to alert everyone... This makes the thought of some sort of virus causing this even more realistic.. no need to check ttl's, just fire away with protocol 103... Yikes... -- --------------------------- Jason H. Frisvold Backbone Engineering Supervisor Penteledata Engineering friz(a)corp.ptd.net RedHat Engineer - RHCE # 807302349405893 Cisco Certified - CCNA # CSCO10151622 MySQL Core Certified - ID# 205982910 --------------------------- "Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world." -- Albert Einstein [1879-1955]

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Re: rfc1918 ignorant
by Kevin Oberman 23 Jul '03

23 Jul '03

> Date: Wed, 23 Jul 2003 14:06:09 -0400 (EDT) > From: Dave Temkin <dave(a)ordinaryworld.com> > > Unless of course I block ICMP for the purposes of denying traceroute but > still allow DF/etc. Then it's not "broken" as you say. And where do the ICMPs come from if the DF bit results in a failure? Surely not an RFC1918 address. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman(a)es.net Phone: +1 510 486-8634

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Re: rfc1918 ignorant
by Kevin Oberman 23 Jul '03

23 Jul '03

> Date: Wed, 23 Jul 2003 13:50:05 -0400 (EDT) > From: Dave Temkin <dave(a)ordinaryworld.com> > Sender: owner-nanog(a)merit.edu > > > Needs is a tough call. Plenty of networks block ICMP at the border and > could very well be using 1918 addressing in between and you'd have no > idea. And the network is broken. People persist in blocking ICMP and then complain when things don't work right. Even if you explain why blocking ICMP is breaking something, they say "ICMP is evil and we have to block it". OK. they are broken and when things don't work, they need to tell their customers that they are choosing to run a network that does not work correctly. (Not that I expect anyone to do this.) I don't see anything "tough" about this call. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman(a)es.net Phone: +1 510 486-8634

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rfc1918 ignorant
by Muir, Ronald 23 Jul '03

23 Jul '03

I have been busy today and not monitoring the list. I hate it when I miss the start of an rfc1918 rant. It feels like old news when you have to go back and read the email string and miss out on the name calling and ranting in real time. -Ron

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RE: rfc1918 ignorant (fwd)
by Dave Temkin 23 Jul '03

23 Jul '03

---------- Forwarded message ---------- Date: Wed, 23 Jul 2003 07:53:26 -1000 From: DOUGS(a)oceanic.com To: oberman(a)es.net Cc: dave(a)ordinaryworld.com Subject: RE: rfc1918 ignorant There's a common misconception reflected here that I wanted to correct. I don't have nanog-post, so I apologize if its not appropriate to reply directly. You may repost my comments if you'd like. [Kevin Oberman <mailto:oberman@es.net> wrote on Wednesday, July 23, 2003 7:07 AM:] > Comcast and many others seem to > blithely ignore this for convenience sake. (It's not like they need a > huge amount of space to give private addresses to these links.) ARIN required cable operators to use RFC 1918 space for the management agents of the bridge cable modems that have been rolled out to the millions of residential cable modem customers. Doing so obviously requires a 1918 address on the cable router, but Cisco's implementation requires that address to be the primary interface address. There is also a publicly routable secondary which in fact is the gateway address to the customer, but isn't the address returned in a traceroute. Cisco has by far the lead in market share of the first gen Docsis cable modem router market so any trace to a cable modem customer is going to show this. In fact, Comcast and others _do_ need a huge amount of private IP space because of this. We didn't "blithely ignore" the RFC, but didn't have a choice in implementation. Perhaps Cisco will improve their implementation for the next round of CMTS development... Filtering of RFC 1918 space by cable ISPs is of course another topic. -Doug- [Kevin Oberman <mailto:oberman@es.net> wrote on Wednesday, July 23, 2003 7:07 AM:] >> Date: Wed, 23 Jul 2003 08:59:18 -0400 (EDT) >> From: Dave Temkin <dave(a)ordinaryworld.com> >> Sender: owner-nanog(a)merit.edu >> >> >> Is this really an issue? So long as they're not advertising the >> space I see no issue with routing traffic through a 10. network as >> transit. If you have no reason to reach their router directly (and >> after Cisco's last exploit, I'd think no one would want anyone to >> reach their router directly :-) ), what's the harm done? >> >> RFC1918 merely states that it shouldn't be routed on the global >> internet, not that it can't be used for transit space. > > That's not what is in my copy of 1918. > > "In order to use private address space, an enterprise needs to > determine which hosts do not need to have network layer connectivity > outside the enterprise in the foreseeable future and thus could be > classified as private. Such hosts will use the private address space > defined above. Private hosts can communicate with all other hosts > inside the enterprise, both public and private. However, they cannot > have IP connectivity to any host outside of the enterprise. While not > having external (outside of the enterprise) IP connectivity private > hosts can still have access to external services via mediating > gateways (e.g., application layer gateways)." > > As I read this, packets with a source address in 19298 space should > NEVER appear outside the enterprise. Comcast and many others seem to > blithely ignore this for convenience sake. (It's not like they need a > huge amount of space to give private addresses to these links.)

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Re: rfc1918 ignorant
by Kevin Oberman 23 Jul '03

23 Jul '03

> Date: Wed, 23 Jul 2003 08:59:18 -0400 (EDT) > From: Dave Temkin <dave(a)ordinaryworld.com> > Sender: owner-nanog(a)merit.edu > > > Is this really an issue? So long as they're not advertising the space I > see no issue with routing traffic through a 10. network as transit. If > you have no reason to reach their router directly (and after Cisco's last > exploit, I'd think no one would want anyone to reach their router directly > :-) ), what's the harm done? > > RFC1918 merely states that it shouldn't be routed on the global internet, > not that it can't be used for transit space. That's not what is in my copy of 1918. "In order to use private address space, an enterprise needs to determine which hosts do not need to have network layer connectivity outside the enterprise in the foreseeable future and thus could be classified as private. Such hosts will use the private address space defined above. Private hosts can communicate with all other hosts inside the enterprise, both public and private. However, they cannot have IP connectivity to any host outside of the enterprise. While not having external (outside of the enterprise) IP connectivity private hosts can still have access to external services via mediating gateways (e.g., application layer gateways)." As I read this, packets with a source address in 19298 space should NEVER appear outside the enterprise. Comcast and many others seem to blithely ignore this for convenience sake. (It's not like they need a huge amount of space to give private addresses to these links.) -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman(a)es.net Phone: +1 510 486-8634

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RE: rfc1918 ignorant
by Daryl G. Jurbala 23 Jul '03

23 Jul '03

Ahhh...but this all comes down to how one defines "enterprise" and it's network scope. IANALBPSB (I am not a lawyer but probably shoud be) Daryl PGP Key: http://www.introspect.net/pgp [...] > That's not what is in my copy of 1918. > > "In order to use private address space, an enterprise needs > to determine which hosts do not need to have network layer > connectivity outside the enterprise in the foreseeable future > and thus could be classified as private. Such hosts will use [...]

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rfc1918 ignorant
by Frank Louwers 23 Jul '03

23 Jul '03

Is there a site to "report" networks/isps that still leak rfc1918 space? By leaking I not only mean "don't filter", but actually _use_ in their network? If someone is keeping a list, feel free to add ServerBeach.com. All traceroutes to servers housed there, pass by 10.10.10.3. traceroute to www.serverbeach.com ... 20. 64-132-228-70.gen.twtelecom.net 21. 10.10.10.3 22. 66.139.72.12 Kind Regards, Frank Louwers -- Openminds bvba www.openminds.be Tweebruggenstraat 16 - 9000 Gent - Belgium

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second call for an unbundled portable /24
by Henry Linneweh 23 Jul '03

23 Jul '03

We have attempted in the past tried to deal with Arin on this issue and they as usual deny anything that could potentially be useful, in thwarting these attacks. There have been some people with good idea's, however when you have a 1 gig bi-directional pipe and you have 2Gb/s incoming these idea's then only look good on paper with nice graphic's to match. I think all the oc48 shelves need to be checked and the passwords changed..... Henry R. Linneweh

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RE: Cisco vulnerability and dangerous filtering techniques
by Austad, Jay 23 Jul '03

23 Jul '03

> How many thousands of "polls" do you think a looking glass can handle > simultaneously? I am all for the doomsday scenarios, but lets > make them a > little bit less sci-fi, shall we? How about "it would create > valid looking > OSPF packets with garbage in them?" or "create valid looking > STP packets" It was just a suggestion. I don't think it's plausible on a wide scale, but only a few queries would be needed to get an overview of the topology. Originally I was thinking traceroutes. It's not going to be exact, but it's going to glean enough information to cause more damage than without that info. If you were doing some sort of p2p, each host would simply need to perform many random traceroutes and correlate their data. The devices that appeared most often in that data would obviously be backbone routers, and the attack would start with those and work to the least frequent (with specific emphasis on the hops that were seen from the local trojan/worm/etc). Like I said, it's not going to be perfect, but it is better than blindly spewing out evil packets. Jay

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