Thank you, Comcast.

Keith Medcalf kmedcalf at dessus.com
Sat Feb 27 00:59:28 UTC 2016


The default configuration of IE (all versions), Firefox (all versions), Edge (all versions) and Chrome (all versions) is a zero-security configuration.  Of course it works fine in a zero-security configuration -- I said that from the get go.

It does not work if you do not permit javascript to run unless approved, and do not permit unapproved (and unapprovable scripts from third-party sites of unknown provenance) to run.  It does not work if you block cross-site access to widgets and crap coming from third-parties of equally unknown provenance.

I do not know what it is looking for, but it cannot do that, so therefore it does not work.

You may not care about how insecure your browser is -- I do.

> -----Original Message-----
> From: NANOG [mailto:nanog-bounces at nanog.org] On Behalf Of Naslund, Steve
> Sent: Friday, 26 February, 2016 10:11
> To: NANOG list
> Subject: RE: Thank you, Comcast.
> 
> Also worked fine in IE 11 and Firefox.  I didn't change any particular
> security settings either.  Might want to check your stuff before you rant
> on someone's web site.
> 
> Steven Naslund
> Chicago IL
> 
> -----Original Message-----
> From: NANOG [mailto:nanog-bounces at nanog.org] On Behalf Of Mike Hammett
> Sent: Friday, February 26, 2016 10:01 AM
> To: NANOG list
> Subject: Re: Thank you, Comcast.
> 
> Works fine on a default Chrome installation. *shrugs*
> 
> 
> 
> 
> -----
> Mike Hammett
> Intelligent Computing Solutions
> http://www.ics-il.com
> 
> Midwest-IX
> http://www.midwest-ix.com
> 
> ----- Original Message -----
> 
> From: "Keith Medcalf" <kmedcalf at dessus.com>
> To: "NANOG list" <nanog at nanog.org>
> Cc: "Nirmal Mody" <Nirmal_Mody at cable.comcast.com>
> Sent: Friday, February 26, 2016 9:55:20 AM
> Subject: RE: Thank you, Comcast.
> 
> 
> On Friday, 26 February, 2016 08:13, Jason_Livingood at comcast.com said:
> 
> > FWIW, Comcast's list of blocked ports is at
> > http://customer.xfinity.com/help-and-support/internet/list-of-blocked-
> > ports/. The suspensions this week are in direct response to reported
> > abuse from amplification attacks, which we obviously take very
> seriously.
> 
> God is that a horrid web page. I cannot view it. The wheels on the bus go
> round and round non-stop.
> 
> It has so much intertwined malicious javascript, cross-site scripting, and
> malicious trackers that the alarm klaxons go off when I attempt to access
> it. I spent a couple of minutes attempting to access the page but still
> maintaining blocks to the malicious links. Apparently, viewing the page
> requires that all security be turned off and that the viewer allows
> completely untrusted code from completely untrustworty sources to run
> unabated on the viewers computer.
> 
> I do not permit this. For anyone. Ever.
> 
> This pretty much ensures that I would never be one of your customers. If
> you cannot operate a server which serves renderable non-malicious web
> pages properly, what hope is there that you can do anything else right?
> 
> > We are in the process of considering adding some new ports to this
> > block list right now, and one big suggestion is SSDP. If you have any
> > others you wish to suggest please send them to me and the guy on the
> > cc line (Nirmal Mody).
> 
> > On 2/26/16, 9:31 AM, "NANOG on behalf of Keith Medcalf" <nanog-
> > bounces at nanog.org on behalf of kmedcalf at dessus.com> wrote:
> >
> >
> >
> > ISP's should block nothing, to or from the customer, unless they make
> > it clear *before* selling the service (and include it in the Terms and
> > Conditions of Service Contract), that they are not selling an Internet
> > connection but are selling a partially functional Internet connection
> > (or a limited Internet Service), and specifying exactly what the
> > built-in deficiencies are.
> >
> > Deficiencies may include:
> > port/protocol blockage toward the customer (destination blocks)
> > port/protocol blockage toward the internet (source blocks) DNS
> > diddling (filtering of responses, NXDOMAIN redirection/wildcards, etc)
> > Traffic Shaping/Policing/Congestion policies, inbound and outbound
> >
> > Some ISPs are good at this and provide opt-in/out methods for at least
> > the first three on the list. Others not so much.
> >
> >
> > -----Original Message-----
> > From: NANOG [mailto:nanog-bounces at nanog.org] On Behalf Of Maxwell Cole
> > Sent: Friday, 26 February, 2016 07:19
> > To: Mikael Abrahamsson
> > Cc: NANOG list
> > Subject: Re: Thank you, Comcast.
> > I agree,
> > At the very least things like SNMP/NTP should be blocked. I mean how
> > many people actually run a legit NTP server out of their home?
> > Dozens? And the
> > people who run SNMP devices with the default/common communities aren't
> > the ones using it.
> > If the argument is that you need a Business class account to run a
> > mail server then I have no problem extending that to DNS servers also.
> > Cheers,
> > Max
> > > On Feb 26, 2016, at 8:55 AM, Mikael Abrahamsson
> > <swmike at swm.pp.se>
> > wrote:
> > >
> > > On Fri, 26 Feb 2016, Nick Hilliard wrote:
> > >
> > >> Traffic from dns-spoofing attacks generally has src port =
> > 53 and dst
> > port = random. If you block packets with udp src port=53 towards
> > customers, you will also block legitimate return traffic if the
> > customers run their own DNS servers or use opendns / google dns / etc.
> > >
> > > Sure, it's a very interesting discussion what ports should
> > be blocked or
> > not.
> > >
> > > http://www.bitag.org/documents/Port-Blocking.pdf
> > >
> > > This mentions on page 3.1, TCP(UDP)/25,135,139 and 445.
> > They've been
> > blocked for a very long time to fix some issues, even though there is
> > legitimate use for these ports.
> > >
> > > So if you're blocking these ports, it seems like a small
> > step to block
> > UDP/TCP/53 towards customers as well. I can't come up with an argument
> > that makes sense to block TCP/25 and then not block port
> > UDP/TCP/53 as
> > well. If you're protecting the Internet from your customers
> > misconfiguraiton by blocking port 25 and the MS ports, why not
> > 53 as well?
> > >
> > > This is a slippery slope of course, and judgement calls are
> > not easy to
> > make.
> > >
> > > --
> > > Mikael Abrahamsson email: swmike at swm.pp.se
> >
> >
> >
> >
> >
> >
> 
> 
> 
> 






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