In message <alpine.deb.2.02.1602260718460.11...@uplift.swm.pp.se>, Mikael Abrah amsson writes: > 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 > case nowadays? > > 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.
Because complaining is like talking to a brick wall most of the time. People work around the ISP idiocy by shifting ports, its easier than trying to get through help desk hell. > -- > Mikael Abrahamsson email: swm...@swm.pp.se -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org
