February 2014 - Test - lists.nanog.org

common checks performed when passing on an IPv4 PA allocation from one end-customer to another
by Martin T 22 Feb '16

22 Feb '16

Hi, when one end-customer has been using for example /24 IPv4 allocation for a while and returns this(for example changes an ISP) to LIR, then are there some good practices before handing out this same /24 to a new customer? I guess LIR should: 1) remove all the DNS PTR records, classless of classful delegations 2) check if some of the IP addresses are in DNSBL(maybe the previous customer was a spammer). Example with 93.184.216.0/24: $ for ip in {0..255}.216.184.93;\ > do for addr in \ > cbl.abuseat.org \ > dnsbl.inps.de \ > no-more-funn.moensted.dk \ > dnsbl.sorbs.net \ > bl.spamcannibal.org \ > bl.spamcop.net \ > psbl.surriel.com \ > dnsrbl.swinog.ch; \ > do dig @8.8.8.8 "$ip"."$addr" +short | grep -q "^127.0.0." && \ > echo "DNSBL-Alarm: $ip is listed on $addr"; done; done $ Anything else? regards, Martin

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Big day for IPv6 - 1% native penetration
by Tomas Podermanski 05 Jan '16

05 Jan '16

Hi, It seems that today is a "big day" for IPv6. It is the very first time when native IPv6 on google statistics (http://www.google.com/intl/en/ipv6/statistics.html) reached 1%. Some might say it is tremendous success after 16 years of deploying IPv6 :-) T.

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How are you doing DHCPv6 ?
by Randy Carpenter 02 Apr '15

02 Apr '15

I am wondering how people out there are using DHCPv6 to handle assigning prefixes to end users. We have a requirement for it to be a redundant server that is centrally located. DHCPv6 will be relayed from each customer access segment. We have been looking at using ISC dhcpd, as that is what we use for v4. However, it currently does not support any redundancy. It also does not do very much useful logging for DHCPv6 requests. Certainly not enough to keep track of users and devices. So, my questions are: How are you doing DHCPv6 with Prefix Delegation? What software are you using? When DHCPv6 with Prefix Delegation seems to be about the only way to deploy IPv6 to end users in a generic device-agnostic fashion, I am wondering why it is so difficult to find a working solution. thanks, -Randy -- | Randy Carpenter | Vice President - IT Services | Red Hat Certified Engineer | First Network Group, Inc. | (800)578-6381, Opt. 1 ----

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Generating IPv6 list with filtergen.level3.net
by Smith, Courtney 28 Mar '15

28 Mar '15

Anyone out there know how to generate a IPv6 list Level3's filtergen? I tried Google but didn't find anything. () ascii ribbon campaign - against html e-mail /\ www.asciiribbon.org - against proprietary attachments

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The state of TACACS+
by Robert Drake 05 Jan '15

05 Jan '15

Ever since first using it I've always liked tacacs+. Having said that I've grown to dislike some things about it recently. I guess, there have always been problems but I've been willing to leave them alone. I don't have time to give the code a real deep inspection, so I'm interested in others thoughts about it. I suspect people have just left it alone because it works. Also I apologize if this is too verbose or technical, or not technical enough, or just hard to read. History: TACACS+ was proposed as a standard to the IETF. They never adopted it and let the standards draft expire in 1998. Since then there have been no official changes to the code. Much has happened between now and then. I specifically was interested in parsing tac_plus logs correctly. After finding idiosyncrasies I decided to look at the source and the RFC to see what was really happening. Logging, or why I got into this mess: In the accounting log, fields are sometimes logged in different order. It appears the client is logging whatever it receives without parsing it or modifying it. That means the remote system is sending them in different orders, so technically the fault lies with them. However, it seems too trusting to take in data and log it without looking at it. This can also cause issues when you send a command like (Cisco) "dir /all nvram:" on a box with many files. The device expands the command to include everything on the nvram (important because you might want to deny access to that command based on something it expanded), but it gets truncated somewhere (not sure if it's the device buffer that is full, tac_plus, or the logging part. I might tcpdump for a while to see if I can figure out what it looks like on the wire) I'm not sure if there are security implications there. Encryption: The existing security consists of md5 XOR <content> with the md5 being composed of a running series of 16 byte hashes, taking the previous hash as part of the seed of the next hash. A sequence number is used so simple replay shouldn't be a factor. Depending on how vulnerable iterative md5 is to it, and how much time you had to sniff the traffic, I would think this would be highly vulnerable to chosen plaintext if you already have a user-level login, or at least partial known plaintext (with the assumption they make backups, you can guess that at least some of the packets will have "show running-config" and other common commands). They also don't pad the encrypted string so you can guess the command (or password) based on the length of the encrypted data. For a better description of the encryption you can read the draft: http://tools.ietf.org/html/draft-grant-tacacs-02 I found an article from May, 2000 which shows that the encryption scheme chosen was insufficient even then. http://www.openwall.com/articles/TACACS+-Protocol-Security For new crypto I would advise multiple cipher support with negotiation so you know what each client and server is capable of. If the client and server supported multiple keys (with a keyid) it would be easier to roll keys frequently, or if it isn't too much overhead they could use public key. Clients: As for clients, Wikipedia lists several that seem to be based on the original open-source tac_plus from Cisco. shrubbery.net has the "official" version that debian and freebsd use. I looked at some of the others and they all seemed to derive from Cisco's code directly or shrubbery.net code, but they retained the name and started doing their own versioning. All the webpages look like they're from 1995. In some cases I think it's intentional but in some ways it shows a lack of care for the code, like it's been dropped since 2000. Documentation is old: This only applies to shrubbery.net's version. I didn't look at the other ones that closely. While all of it appears valid, one Q&A in the FAQ was about IOS 10.3/11.0. Performance questions use the sparc 2 as a target machine. There isn't an INSTALL or README, just the FAQ/CHANGES/COPYING (and a tac_plus.conf manpage), so the learning curve for new users is probably pretty steep. Also there isn't a clear maintainer. The best email address I found was listed in the tacacs+.spec file, for packaging on rpm systems. If you hit the website they give some hints with some outdated, though still functional links. And they list the official email as tac_plus(a)shrubbery.net Conclusion: Did everyone already know this but me? If so have you moved to Kerberos? Can Kerberos do everything TACACS+ was doing for router authorization? I've got gear that only supports radius and tacacsplus, so in some cases I have no choice but to use one of those, neither of which I would trust over an unencrypted wire. If TACACS+ isn't a dead end then it needs a push to bring the protocol to a new version. There are big name vendors involved in making supported clients and servers. There should be someone invested in keeping it secure and adding features.

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Re: EIGRP support !Cisco
by Nick Olsen 18 Apr '14

18 Apr '14

This is what I figured from a quick googling. Just wanted to make sure I wasn't missing anything.. Thanks! Nick Olsen Network Operations (855) FLSPEED x106 ---------------------------------------- From: "Nick Hilliard" <nick(a)foobar.org> Sent: Wednesday, January 08, 2014 1:03 PM To: nick(a)flhsi.com, nanog(a)nanog.org Subject: Re: EIGRP support !Cisco On 08/01/2014 17:52, Nick Olsen wrote: > Completely agree. But this is needed to integrate into an existing network. > OSPF would've been my first choice. you'll need to pay cisco tax then. Cisco opened up most of eigrp to the ietf as an informational rfc, but didn't release anything related to eigrp stub areas. This means that the ietf release is not that useful if a vendor wanted feature parity with cisco's implementation. So far I'm not aware of any vendors who have implemented it. Maybe some will do so in future. Nick

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Filter NTP traffic by packet size?
by Edward Roels 03 Mar '14

03 Mar '14

Curious if anyone else thinks filtering out NTP packets above a certain packet size is a good or terrible idea. >From my brief testing it seems 90 bytes for IPv4 and 110 bytes for IPv6 are typical for a client to successfully synchronize to an NTP server. If I query a server for it's list of peers (ntpq -np <ip>) I've seen packets as large as 522 bytes in a single packet in response to a 54 byte query. I'll admit I'm not 100% clear of the what is happening protocol-wise when I perform this query. I see there are multiple packets back forth between me and the server depending on the number of peers it has? Would I be breaking something important if I started to filter NTP packets > 200 bytes into my network?

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Verizon FIOS IPv6?
by Tristan Lear 02 Mar '14

02 Mar '14

My strategy, should I remember it tomorrow: We have a business-class FIOS connection where I work and a static IP as well. At least three people who work here have FIOS at home. I've read rumors about business class customers who really work their phone sex getting native ipv6, and I also heard somethin about static ip's. So I'll try that, and also mention that "we're transitioning our employees who remote in from home to FIOS but we'd like ipv6 for ... VPN purposes, NAT traversal, etc ..." I mean, that should get them a little wet right? I have a bit of a hairbrained theory that the reason ISP's have stagnated on ipv6 has to do with relationship between capitalism and scarcity. Having a limited quantity of anything makes it more valuable. Why wouldn't that apply to IP's?

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Managing IOS Configuration Snippets
by Ryan Shea 02 Mar '14

02 Mar '14

Howdy network operator cognoscenti, I'd love to hear your creative and workable solutions for a way to track in-line the configuration revisions you have on your cisco-like devices. Let me clearify/frame: You have a set of tested/approved configurations for your routers which use IOS style configuration. These configurations of course are always refined and updated. You break these pieces of configuration into logical sections, for example a configuration file for NTP configuration, a file for control plane filter and store these in some revision control system. Put aside for the moment whether this is a reasonable way to comprehend deployed configurations. What methods do some of you use to know which version of a configuration you have deployed to a given router for auditing and update purposes? Remarks are a convenient way to do this for ACLs - but I don't have similar mechanics for top level configurations. About a decade ago I thought I'd be super clever and encode versioning information into the snmp location - but that is just awful and there is a much better way everyone is using, right? Flexible commenting on other vendors/platforms make this a bit easier. Assume that this version encoding perfectly captures what is on the router and that no person is monkeying with the config... version 77 of the control plane filter is the same everywhere.

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Any experience with Comcast digital voice for OOB (offlist is fine)
by eric-list＠truenet.com 01 Mar '14

01 Mar '14

Sincerely, Eric Tykwinski TrueNet, Inc. P: 610-429-8300 F: 610-429-3222

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