Breaking the internet (hotels, guestnet style)

Steven Bellovin smb at cs.columbia.edu
Mon Dec 7 20:48:25 CST 2009


On Dec 7, 2009, at 6:00 PM, Jared Mauch wrote:

> 
> On Dec 7, 2009, at 5:29 PM, John Levine wrote:
> 
>>> 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".
>> 
>> 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.
> 
> I've found more and more hotel/edge networks blocking/capturing this traffic.
> 
> The biggest problem is they tend to break things horribly and fail things like the
> oarc entropy test.
> 
> They will often also return REFUSED (randomly) to valid well formed DNS queries.
> 
> 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.
> 
> 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









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