Thank you, Comcast.
nanog at ics-il.net
Fri Feb 26 12:36:46 UTC 2016
I do on my network (well, the ISP, not the IX). It makes complete sense.
Intelligent Computing Solutions
----- Original Message -----
From: "Mikael Abrahamsson" <swmike at swm.pp.se>
To: "Jared Mauch" <jared at puck.nether.net>
Cc: "NANOG list" <nanog at nanog.org>
Sent: Friday, February 26, 2016 12:20:28 AM
Subject: Re: Thank you, Comcast.
On Thu, 25 Feb 2016, Jared Mauch wrote:
> Make sure you permit TCP/53 for DNS queries so if TC=1 lookups work.
Speaking of which, historically ISPs have been blocking TCP/135, TCP/445
and a few others towards customers (at least that's what I know). TCP/25
seems to be blocked as well.
Why isn't UDP/53 blocked towards customers? I know historically there were
resolvers that used UDP/53 as source port for queries, but is this the
I know providers that have blocked UDP/53 towards customers as a
countermeasure to the amplification attacks. As far as I heard, there were
no customer complaints.
Mikael Abrahamsson email: swmike at swm.pp.se
More information about the NANOG