[12/8/2010: This post seems to have been lost in my transformation from MT to WP. Sorry.]
Monthly Archives: November 2010
John Levine explains Why DNS blacklists don't work for IPv6 networks.
The reason is the vastly large IPv6 address space. IPv4 addressses are 32 bits long, allowing 4 billion addresses. That seems like (and is) a lot, but it's few enough that all the addresses will be handed out by sometime next year, and any given network has only a limited supply of them. This means that a single host usually has a single IPv4 address, or at most a few hundred addresses. IPv6 addresses are much longer, 128 bits long. They are so long that where as in IPv4, an ISP usually allocates a single IP address to each customer, ISPs will probably allocate a /64 of IPv6 space to each customer, that is, a range of addresses 64 bits long. While there are sensible technical reasons to do this, it also has the unfortunate effect that a computer can switch to a new IP address each time it sends a new message, and never reuse an address. (As a rough approximation, if you sent a billion messages a second, each with its own address, it would take about a thousand years to use all the addresses in a /64.)
He also has some suggestions for how to overcome the problem, but I'm skeptical about the workability of at least the first two of his ideas, which are whitelists or modifying DNSSEC to suit (it took forever to get the current version agreed).
Then again, who actually uses IPv6 for email anyway?
Happy low-sodium, low-sugar, low-cholesterol, low alcohol, measured Vitamin K Thanksgiving!
We arrived very early for our flight, fearing long waits for our turn at being groped. But in fact there were no queues at the security screening, and more TSA people than I have ever seen in one place.
At our concourse (“D”) they had both metal detectors and what I think were backscatter machines right next to each other. Most people were being run through the metal detector, a few through the scanners. None of us got picked for it; we all went through the metal detector and that was that. (Once again my metal valve didn't set it off.)
Then we spent a very long time in the airport waiting for our flight.
Matt Kernan was entering the USA, at Cincinnati/Northern Kentucky International Airport. He didn't have a connecting flight — he was heading home. The TSA wanted to subject him, as it apparently does all incoming passengers, to its glow or grope policy.
The problem, from the TSA's point of view, is that the arguably exigent circumstances that may exist for subjecting passengers to an intrusive suspicionless search when they are about to board an airplane — the fear of terrorist attack on a plane — do not exist when people are trying to leave the airport.
Mr. Kerman had four things many passengers do not have:
- He had time.
- He had, it appears, the iron self-control needed to remain polite at all times.
- He had a recording device (voice only).
- He had a good understanding of his rights.
Read all about it at the misnamed You Don't Need to See His Identification — misnamed, because in practice they do need to see your ID to establish that you are a citizen with a right to reenter the country. (Yes, there are rare cases of people establishing their right to re-enter by witness testimony when they have lost their passports, but that's not something you want to get into.)
To the lawyer's eye there are a few critical points here. The first is that, once you have successfully identified yourself as a US citizen and undergone the ordinary customs process to demonstrate an absence of contraband, you have an absolute legal right to re-enter the US. Court decisions are very clear about this.
The second point is that Mr. Kernan was very careful at all times to say he would comply with any order, but would not accede to invasive searches unless he was told he was being required to submit to it. This is the thing that no one wanted to go on the record as saying, most probably because the TSA's legal position on this is much, much shakier than for passengers attempting to board aircraft. Mr. Kernan also understood that asking a police officer if he was being detained or was free to go is the magic phrase which invokes your Constitutional rights.
I can't emphasize enough that anyone trying to do this better have a lot of time — it took Mr. Kernan 2.5 hours to get through the checkpoint — and especially the iron self-control to remain polite while dealing with officious and occasionally intimidating officialdom. There is a real chance of arrest; if your behavior was perfect it would, I think, be a false arrest, but absent a tape the chances of proving you were not causing a disturbance, or interference with an officer's pursuit of his duty, would not be good enough to make me happy. Mr. Kernan had the good fortune to engage with well-trained and and sensible local police officers and TSA officials who were not in the end vindictive. Your mileage may vary.
And there's the rub: the constitutional right to enter the country freely is made so risky and difficult to exercise as to be rendered almost meaningless.
(Spotted via boingboing's Traveller re-enters USA without passing through a pornoscanner or having his genitals touched.)