How not to set up your DNS (part 3)
Presented once again in illustration:
; sdig ns isotech.com.cydns2.lordosinfo.com.dns1.lordosinfo.com.; sdig ns lordosinfo.com.dns1.edynet.com.cy.dns1.lordosinfo.com.; sdig ns edynet.com.cy.dns2.netconnect.com.cy.dns1.netconnect.com.cy.
At the moment:
- dns2.netconnect.com.cy is not responding,
- dns1.edynet.com
Weekly spam summary on November 26th, 2005
This week we received 20,583 email messages from 213 different IPaddresses. Our SMTP server handled 21,213 sessions from 1,044different IP addresses. This is a significant jump in incoming emailcompared to last week .
We saw a major jump in connections compared to last week :238,300 connections from at least 32,400 different IP addresses.Broken down by day, it goes:
| Day | Connections | different IPs |
| Sunday |
How not to set up your DNS (part 1)
Presented in illustrations:
; dig +short ns harvest.idv.tw.harvest.idv.tw.www.harvest.idv.tw.; dig +short a harvest.idv.tw.219.84.30.59; dig +short a www.harvest.idv.tw.219.84.30.59
To those setting up nameservers: when people said 'have twonameservers', they did not mean 'and feel free
How not to set up your DNS (part 2)
Today's examples of MX entries are all drawn from domains presented toour mailer in MAIL FROM 's over the past 28 days or so. ' sdig ' is ascript that does a ' dig +short '. Presented in illustrated form:
; sdig mx oakhavenresort.com.10 mail.10 mail.oakhavenresort.com.
It's interesting that they get this simultaneously wrong and right. Isthe plain ' mail. ' supposed to be in some other domain?
; sdig mx
A little sysadmin twitch
Every system administrator has little twitches, behaviors that strikeoutside observers as somewhere between odd and superstitious. Sometimesthese are just habits, but sometimes they have interesting storiesbehind them.
One of my twitches is that when I use su , I always type ' /bin/su '(or on some irritating systems, ' /usr/bin/su '), not plain ' su '.(By now it's a reflex.)
This habit originated in a bit of security advice. The story goes
Making self-signed SSL certificates with OpenSSL
So that I don't have to try to remember it or look it up next timearound, here is how to generate a real self-signed SSL certificate withOpenSSL. The basic but incomplete incantation is:
openssl req -x509 -nodes -days-keyout .key -out .crt ... If you want a merged PEM certificate, just make the
-keyoutand-outarguments the same thing. The key (or the PEM
Solaris 9's slow patch installs
Yesterday was my first time installing the Solaris 9 recommended patchset on a production machine; we rolled it onto a basically unpatchedserver. Because it was a server, I did it in single user mode (thepatch set recommends this, as some patches in the patch set sayexplicitly to apply them in single-user mode).
I already knew that installing the patch set was achingly slow on mytest machine, but my test machine is an Ultra 10 so I wasn'tsurprised. The machine from
Multiprocessors are a leaky abstraction
Earlier this week, the story started rumbling through the usual places that using hyperthreading on Intel CPUs could cause seriousperformance problems in some applications, like Microsoft SQL Server.The current best guess of the cause is cache thrashing due toHyperthreaded processors sharing L1 and L2 cache. If a process thathammers the cache is scheduled onto one logical processor of a HTpair, it will destroy the performance of anything running on theother logical CPU (I'm summarizing from here ).
As this vividly demonstrates, multiprocessors
A quick outline of Firefox extension structure
Yesterday I mentioned Firefox extensions inpassing. Let's fill in the blanks.
Firefox extensions come as
.xpifiles, which are just yet anotherextension for ZIP archives. Unpacked, extensions live in their owndirectory in theextensions/subdirectory in your Firefox profiledirectory. Firefox profile directories live under~/.mozilla/firefox; the default profile is in.default .(Firefox randomizes the name of the profile directory, I believe dueto security concerns.) The actual name of an extension
How to fiddle with Firefox .jar files relatively easily
A lot of Firefox's code is actually written in various interpretedlanguages, especially JavaScript, and Firefox extensions are prettymuch all interpreted. This means that you can do a lot of Firefox andextension hacking without ever having to rebuild from source; you justzap the interpreted files in place in your installed copy.
Firefox doesn't leave all of these files sitting around for you toedit; it bundles them up in various
.jarfiles (pretty much all inthechrome/subdirectory). Fortunately.jarMenu