Isn't blocking any port against the idea of Net Neutrality?
Justin Shore wrote:
Owen DeLong wrote:
Blocking ports that the end user has not asked for is bad.
I was going to ask for a clarification to make sure I read your
statement correctly but then again it's short enough I really don't
see any room to misinterpret it. Do you seriously think that a
typical residential user has the required level of knowledge to call
their SP and ask for them to block tcp/25, tcp & udp/1433 and 1434,
and a whole list of common open proxy ports? While they're at it they
might ask the SP to block the C&C ports for Bobax and Kraken. I'm
sure all residential users know that they use ports 447 and 13789. If
so then send me some of your users. You must be serving users around
the MIT campus.
Doing it and refusing to unblock is worse.
How you you propose we pull a customer's dynamically-assigned IP out
of a DHCP pool so we can treat it differently? Not all SPs use
customer-facing AUTH. I can think of none that do for CATV though I'm
sure someone will now point an oddball SP that I've never heard of
before.
Some ISPs have the even worse practice of blocking 587 and a few even
go to the horrible length to block 465.
I would call that a very bad practice. I haven't personally seen a
mis-configured MTA listening on the MSP port so I don't think they can
make he claim that the MSP port is a common security risk. I would
call tcp/587 a very safe port to have traverse my network. I think
those ISPs are either demonstrating willful ignorance or marketing
malice.
A few hotel gateways I have encountered are dumb enough to think they
can block TCP/53
which is always fun.
The hotel I stayed in 2 weeks ago that housed a GK class I took had
just such a proxy. It screwed up DNS but even worse it completely
hosed anything trying to tunnel over HTTP. OCS was dead in the
water. My RPC-over-HTTP Outlook client couldn't work either.
Fortunately they didn't mess with IPSec VPN or SSH. Either way it
didn't matter much since the network was unusable (12 visible APs from
room, all on overlapping 802.11b/g channels). The average throughput
was .02Mbps.
Lovely for you, but, not particularly helpful to your customers who
may actually want to use some of those services.
I take a hard line on this. I will not let the technical ignorance of
the average residential user harm my other customers. There is
absolutely no excuse for using Netbios or MS-SQL over the Internet
outside of an encrypted tunnel. Any user smart enough to use a proxy
is smart enough to pick a non-default port. Any residential user
running a proxy server locally is in violation of our AUP anyway and
will get warned and then terminated. My filtering helps 99.99% of my
userbase. The .001% that find this basic security filter intolerable
can speak with their wallets. They can find themselves another
provider if they want to use those ports or pay for a business circuit
where we filter very little on the assumption they as a business have
the technical competence to handle basic security on their own. (The
actual percentage of users that have raised concerns in the past 3
years is .0008%. I spoke with each of them and none decided to leave
our service.)
We've been down the road of no customer-facing ingress ACLs. We've
fought the battles of getting large swaths of IPs blacklisted because
of a few users' technical incompetence. We've had large portions of
our network null-routed in large SPs. Then we got our act together
and stopped acting like those ISPs who we all love to bitch about,
that do not manage their customer traffic, and are poor netizens of
this shared resource we call the Internet. Our problems have all but
gone away. Our residential and business users no longer call in on a
daily basis to report blacklisting problems. We no longer have
reachability issues with networks that got fed up with the abuse
coming from our compromised users and null-routed us. I stand by our
results as proof that what we're doing is right. Our customers seem
to agree and that's what matters.
Justin
