The many IPv6 addresses of an IPv4 machine
Ignoring things like link-local addresses, a dual-stack machine withan IPv4 address can have and see at least four different sorts of IPv6addresses:
Forcing your webpage content to scroll is generally a bad idea
Every so often, website designers do things that make me clutch myhead like a stunned monkey, so today I have an open letter for them.
Dear website designers: please understand that stuffing your pagecontents into a restricted space and forcing it to scroll when itdoesn't fit is not a good idea, at least not if you want people toactually read it. No one likes reading content through a little viewportwhen they have their full browser window available, and reading contentthat requires horizontal scrolling is generally
Beware of using Linux's hostname -s switch
The hostname program has a common switch, -s , which is documented(in the Linux version) as:
-s, --short- Display the short host name. This is the host namecut at the first dot.
Although you would not expect it from this description, running' hostname -s ' will do a gethostbyname() and thus often a DNS lookupin most Linux versions of hostname . This can of course fail if yourDNS is not working, which winds up with the very peculiar result
Some thoughts about 6to4
I've previously written about theproblems with the IPv4 to IPv6 transition, and how the IPv6 peoplecould have made it easier . Well,it turns out that I have to take back some of the grumpy thingsthat I said back then because I just found out about 6to4 , which makes IPv6 connectivityfairly trivial for machines with public IPv4 addresses (and generally itworks), partly by embedding the IPv4 address space into IPv6.
(I'll let you read
Why your program should have an actual configuration file
Every so often, someone says something like 'you know, our program has aconfiguration file but also supports runtime reconfiguration via somemagic. Clearly this is wrong, so what we should do is get rid of ourconfiguration file and just make sure the running state is persistent'.If they're feeling nice, they add that the running state will be savedas an XML file.
Every time people say this, sysadmins cry. Here is a very importantthing for real deployments of your program in real environments
A thought on deliberately slow disaster recovery
Given my earlier entry , here is athesis: some disasters are big enough that you should stop trying torecover rapidly .
The problem with attempting rapid disaster recovery is that significantdisasters are high stress, high pressure situations. Unless you have very good checklists , this is exactly the sort ofsituation where it's easy to have something go catastrophically wrongthrough various situations; missed steps, miscommunication betweenpeople about who was doing what, failing to notice problem indicatorsunder the pressure of driving full speed ahead, interruptions and
The problem with blog footnotes
Here is something that has just occurred to me (courtesy of seeing anexample of it): footnotes are hard to do well in blogs, and may needactual software support if you want them to be completely correct.
The conventional way of doing footnotes in HTML is to use fragment URLsand anchors, with the footnote text at the bottom of the entry andyour choice of footnote markers in the main text. But, like anythinginvolving anchors, this means that you need to come up with uniqueanchor names.
Why a laptop is not likely to be my primary machine any time soon
I know and read a number of people who use laptops as their primarymachines, but I'm one of the people who's not interested in the idea(even ignoring any issues of relative prices). I wound up actuallythinking about the question recently, and as it turns out I think Ihave a fairly odd set of reasons for it.
So, here they are so far:
- I have very particular tastes in keyboards (I have used a BTC-5100Ckeyboard for more
Emergency procedures checklists need check steps
Given my previous entry , here is athesis about emergency procedure documentation: you shouldn't just havea checklist for what to do, your checklist should include actual checksteps , points where you stop to explicitly confirm that you've donesomething and it actually works.
Checklists are a good idea , but the common form of achecklist is just a list of steps to be carried out. Under the stress ofan emergency situation, I don't think that this is good enough. First,your checklist
Link: Pollution in 1.0.0.0/8
IANA has recently allocated 1.0.0.0/8 to APNIC, which hascaused a certain amount of concern that it is 'polluted' bypeople already using it for various reasons. Pollution in 1/8 is a report from RIPE Labson what happened when they announced routing for some bits of it as partof their debogonising work .
This is clearly going to be what they call 'interesting'.
(via Hacker News .)