Veganism & The “Carrying Capacity” Of Different Diets

 Media, Politics  No Responses »
Mar 052017
 

There is an article being advertised around that uses a scientific report detailing the carrying capacity (how many people agriculture can support) of different diets. The article itself is titled in a way to bash vegans for not being as environmentally friendly as they claim to be. Which is odd because the scientific report does show that a vegan diet is more efficient (in terms of how many people can be fed) than a normal diet; it’s just not quite as efficient as some diets – specifically diets that make use of grazing land that cannot be otherwise used.

So a relatively mainstream article is bashing vegans because?

Well the usual reason is because of the holier than thou attitude of vegans. Actually it’s the militant fundamentalist wing of the vegans who do the whole holier than thou thing; just like an iceberg most of the vegan population isn’t visible.

Of course any reputable news organisation would know this, so only resorts to demonisation of vegans as click-bait. Obviously desperate.

The interesting thing about the report is that they have actually shown that different diets can be more efficient (in terms of the number of people that can be fed) than others, and that the average diet is probably one of the least efficient possible diets. Even more interesting (especially for the meat eaters out there) is that omnivorous diets (admittedly with significantly reduced meat intake) can be even more efficient than a vegan diet.

This is apparently due to the fact that a vegan diet will not make use of marginal grazing land which can only be used for raising meat.

If the doom-mongers are right about climate change and rising population, all those dedicated meat eaters out there should probably be encouraging vegans (and vegetarians) so when things get marginal, there are still a few animals to share out.

Should Politicians Be Profiled?

 Politics  No Responses »
Feb 282017
 

With the enfant terrible Trump in charge of the USA and petulant Putin in charge of the Russian bear, it seems like an interesting idea to subject politicians to psychological profiling to determine their suitability for public office and power over us.

When you look at the list of monstrous political leaders we have had over just the last 100 years – Hitler, Pol-pot, Stalin, etc., the idea of testing politicians to find out if they are psychos or loonies starts to make a great deal of sense.

The first complaint about this would be that it would be an invasion of privacy. Well we don’t need to know the details; we simply need to have a trustworthy organisation certify that person A is suitable (or unsuitable) candidate.

The second issue is determining just what makes a suitable or unsuitable candidate which is something we need to persuade a bunch of psychologists and psychiatrists to propose.

The final issue is to get politicians to agree to it, and there we can simply refuse to vote for any candidate who has not been certified.

How Cloud Services Do Mail Wrong

 Computing  No Responses »
Feb 272017
 

Strictly speaking how some cloud services do mail wrong, but whilst it is not all, there are still quite a few that do which is why there are no names contained within this rant.

When you have some cloud-based service send email, it makes sense for the “From” header (i.e. what sensible normal people think of as the sender address) to contain the email address of the person using the cloud-based service.

Fair enough.

But if the real sender address or envelope sender address (which is contained within the SMTP transaction) comprises the email address of the person using the cloud-based service you may well run into problems. Many organisations publish an SPF record in their DNS to indicate what network addresses are approved for, and many mail servers check the envelope sender against the published authorised network addresses.

If the network address used by the cloud service provider does not match what is in the organisation’s SPF record then the recipient’s mail server is free to reject the mail. And they often do.

Now the most obvious “fix” for this is to add the cloud service provider’s network address to the organisation’s SPF record.

The only trouble with that is that it isn’t always possible. There are various limits to how long an SPF record can be so adding addresses to the SPF record recklessly is unwise, and a sensible DNS administrator will only add to the SPF record for important services. So if the cloud service is being evaluated or being used by something less important, or is being used for non-work related purposes, then it likely won’t meet the “important enough to get added to the SPF record” criteria.

So why not fix the source of the problem?

All that has to be done is to use a different address for the envelope sender, and you can even arrange things to send bounces back to the right place.

Set the envelope sender to something like “customer+${original email}@${cloud service address}” (obviously when replacing the ${original email} you will have to change the “@” sign to something reversible). All of a sudden you are no longer “forging” the envelope sender, and not tripping over anyone’s spam defences.

Process the bounces to “customer@${cloud service address}” and you can send the bounces to the right place.

Evolution vs. Intelligent Design (Creationism)

 Religion, Science  No Responses »
Feb 132017
 

As an atheist, I find it difficult to be polite and not fall about laughing at things like “Intelligent Design”, but for the duration of this blog posting, I’ll try.

On one side are the scientists who spend their working lives investigating biological processes who have their theory of evolution. Now that word “theory” needs a bit of explanation; it does not mean that evolution hasn’t been accepted as fact by scientists. Evolution is one of those rare scientific theories that has never been disproved; merely refined. Essentially the word “theory” here is a challenge to disprove evolution and come up with a better theory – if you think you’re hard enough!

On the other side are a collection of religious leaders (admittedly Charles Thaxton trained as a chemist) who have spent their working lives telling people about god; and coming up with the theory of “Intelligent Design” in their spare time. The suspicion is that these people are letting their religious beliefs influence their “scientific” thinking.

When I want to know about plumbing, I ask a plumber. When I want to know about welding, I ask a boiler-maker. And when I want to know about biology, I ask a biologist.

Exim: Rejecting Mail With No Reverse DNS

 Computing, Linux, Security, Working Notes  No Responses »
Feb 122017
 

A very long time ago, I used to collect spam in order to graph how much spam a single mail server was likely to get over time, and almost as long ago, I lost interest in maintaining it. As a consequence I still get a ton of spam every day and after a long period of procrastination I have been slowly raising defences against spam.

This particular recipe is not really a defence against spam – it verifies that the remote server is properly DNS registered with a reverse DNS registration – in other words that the IP address it is connecting from is registered. This is a requirement for all mail servers, and as it turns out, spammers don’t care for registering their servers in the DNS.

This ACL snippet goes into the ACL for checking the recipient or for checking the message :-

 deny
   message = Your mail server is not properly DNS registered
   log_message = BLOCKED: No rDNS
   condition = ${if eq{$host_lookup_failed} {1} {1}{0}}
   # Check rDNS and block if not registered

There are three items of interest :-

  1. The message is intended to be easily read by recipients to determine what the problem is. It turns out that many people do not read NDRs, but if we get the message right at least we are doing the right thing.
  2. The log_message is intended to make automating log parsing easier.
  3. Within the condition, the $host_lookup_failed variable indicates that the reverse DNS lookup returned NXDOMAIN and not that it timed out (which would be $host_lookup_deferred).

That’s all there is to this little piece of configuration.

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