[120008] in North American Network Operators' Group
Re: Breaking the internet (hotels, guestnet style)
daemon@ATHENA.MIT.EDU (Steven Bellovin)
Mon Dec 7 21:51:21 2009
From: Steven Bellovin <smb@cs.columbia.edu>
In-Reply-To: <3512DFEB-431F-4EDB-A8DB-7ACC04FF7A43@puck.nether.net>
Date: Mon, 7 Dec 2009 21:48:25 -0500
To: Jared Mauch <jared@puck.nether.net>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Dec 7, 2009, at 6:00 PM, Jared Mauch wrote:
>=20
> On Dec 7, 2009, at 5:29 PM, John Levine wrote:
>=20
>>> Will be interesting to see if ISPs respond to a large scale thing =
like
>>> this taking hold by blocking UDP/TCP 53 like many now do with tcp/25
>>> (albeit for other reasons). Therein lies the problem with some of =
the
>>> "net neturality" arguments .. there's a big difference between =
"doing it
>>> because it causes a problem for others", and "doing it because it =
robs
>>> me of revenue opportunities".
>>=20
>> I do hear of ISPs blocking requests to random offsite DNS servers.
>> For most consumer PCs, that's more likely to be a zombie doing DNS
>> hijacking than anything legitimate. If they happen also to block
>> 8.8.8.8 that's just an incidental side benefit.
>=20
> I've found more and more hotel/edge networks blocking/capturing this =
traffic.
>=20
> The biggest problem is they tend to break things horribly and fail =
things like the
> oarc entropy test.
>=20
> They will often also return REFUSED (randomly) to valid well formed =
DNS queries.
>=20
> While I support the capturing of malware compromised machines until =
they are
> repaired, I do think more intelligence needs to be applied when =
directing these systems.
>=20
> Internet access in a hotel does not mean just UDP/53 to their selected =
hosts plus TCP/80,
> TCP/443.
It's why I run an ssh server on 443 somewhere -- and as needed, I =
ssh-tunnel http to a squid proxy, smtp, and as many IMAP/SSL connections =
as I really need...
--Steve Bellovin, http://www.cs.columbia.edu/~smb
