Greetings,
On Fri, 26 Feb 2016, Keith Medcalf 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.
I wholeheartedly agree! When purchasing an "Internet connection", we
expect that to be full access to the Internet. Granted, *some* parts of
the Internet are up/down or never available, but the *protocols* should
*ALL* be available.
Customers regularly use various VPN protocols from GRE, SIT, and IPIP,
monitoring protocols such as SNMP, as well as RTP and SIP (where we spend
the bulk of our time troubleshooting). Customers EXPECT their packets to
be passed unhampered. Otherwise, all the provider is giving them is acces
to email and to surf for porn. That provider would simply be offering an
"entertainment" connection to the public Internet, not full Internet
access.
However, if a 'provider' wishes to block ANYTHING, then they need to
inform the customer IN WRITING exactly what will be blocked so that
customer doesn't waste their time and money with said (limited) service
and vote with their wallet by buying *real* Internet service, elsewhere.
--- Jay Nugent
Nugent Telecommunications consulting
Ypsilanti, Michigan
-----Original Message-----
From: NANOG [mailto:nanog-boun...@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 <swm...@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: swm...@swm.pp.se
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