Author: Barry O'Donovan

Querying for DNS Glue Records (using dig)

On a project I’m working on, I need to establish if a domain has IPv6 glue records or not. If I had to do it on a once off, a whois lookup would answer that nicely:

$ /usr/bin/whois opensolutions.ie
<snip>
nserver:     dns1.dns.opensolutions.ie 87.232.1.40 2a01:268:4::40
nserver:     dns2.dns.opensolutions.ie 87.232.1.41 2a01:268:4::41
nserver:     dns3.dns.opensolutions.ie 87.232.16.61 2a01:268:3002::61

However, in this case, I will need to do it many times on many domains and do not need to have to worry about whois servers limiting the queries or parsing the output from different whois servers.

After some digging, it looks like the nameservers of TLDs return glue records in the additional section. Let’s look by example on opensolutions.ie. First, find the TLD servers for .ie:

$ dig NS ie
<snip>
;; ANSWER SECTION:
ie.                     172800  IN      NS      gns1.domainregistry.ie.
ie.                     172800  IN      NS      uucp-gw-1.pa.dec.com.
ie.                     172800  IN      NS      uucp-gw-2.pa.dec.com.
ie.                     172800  IN      NS      ns3.ns.esat.net.
ie.                     172800  IN      NS      banba.domainregistry.ie.
ie.                     172800  IN      NS      ice.netsource.ie.
ie.                     172800  IN      NS      gns2.domainregistry.ie.
ie.                     172800  IN      NS      ns-ie.nic.fr.
ie.                     172800  IN      NS      b.iedr.ie.

Now query one of these for the nameservers for opensolutions.ie:

$ dig NS opensolutions.ie @banba.domainregistry.ie.
<snip>
;; AUTHORITY SECTION:
opensolutions.ie.       172800  IN      NS      dns3.dns.opensolutions.ie.
opensolutions.ie.       172800  IN      NS      dns2.dns.opensolutions.ie.
opensolutions.ie.       172800  IN      NS      dns1.dns.opensolutions.ie.

;; ADDITIONAL SECTION:
dns1.dns.opensolutions.ie. 172800 IN    A       87.232.1.40
dns1.dns.opensolutions.ie. 172800 IN    AAAA    2a01:268:4::40
dns2.dns.opensolutions.ie. 172800 IN    A       87.232.1.41
dns2.dns.opensolutions.ie. 172800 IN    AAAA    2a01:268:4::41
dns3.dns.opensolutions.ie. 172800 IN    A       87.232.16.61
dns3.dns.opensolutions.ie. 172800 IN    AAAA    2a01:268:3002::61

As you can see, the authority section contains the nameservers for opensolutions.ie which are all on the opensolutions.ie domain. We then find the glue records for these nameservers in the additional section.

GIMP: Change Background from Black / White to Transparent

This is one that I find myself Googling for regularly but spend time wading through poor results and solutions:

http://brainsongimp.blogspot.com/2008/03/black-and-white-jpg-to-transparent-png.html

Changing a User’s UID on Apple XServe / Snow Leopard

Due to exporting NFS file systems from Linux boxes to an XServe, I had need to match the new users’ UID on the XServe to the Linux UIDs. Unfortunately this was not so obvious.

There’s a good how-to here:

http://www.inteller.net/notes/change-user-id-on-snow-leopard

Fix for Silly Annoying FreeBSD PHP Ports Errors

The following occurs quite regularly on FreeBSD:

Cannot find autoconf. Please check your autoconf installation and the
$PHP_AUTOCONF environment variable. Then, rerun this script.

and when fixed, it’s followed up by:

Cannot find autoheader. Please check your autoconf installation and the
$PHP_AUTOHEADER environment variable. Then, rerun this script.

The fix is to set those environment variables (as appropriate for the autoconf and autoheader version numbers – the below is my example on FreeBSD 8.1):

export PHP_AUTOCONF=/usr/local/bin/autoconf-2.68
export PHP_AUTOHEADER=/usr/local/bin/autoheader-2.68

in bash of the following in tcsh: 

setenv PHP_AUTOCONF autoconf-2.68
setenv PHP_AUTOHEADER autoheader-2.68

Irish Radio Stations on Linux

UPDATED VERSION AVAILABLE: https://www.barryodonovan.com/index.php/2013/02/12/irish-radio-stations-on-linux-2013

I’m a bit of a newstalk junky and like to have the radio on in the back ground. It’s quite painful jumping between websites and even more painful getting them all to work under Linux so I have some simple Bash aliases for VLC and RTE Radio 1, Today FM and Newstalk:

alias 2fm='cvlc http://dynamic.rte.ie/av/live/radio/2fm.asx'
alias newstalk='cvlc http://newstalk.fmstreams.com:8008/listen.pls'
alias rteradio1='cvlc http://dynamic.rte.ie/av/live/radio/radio1.asx'
alias todayfm='cvlc http://audiostore.todayfm.com/audio/todayfmIRL_64K.asx'

UPDATED 2011-02-07: 2FM added.

Good Experience with the CSO and Revenue

I complained about bad experiences with FAS on this blog lately (it actually got worse than that lately) so I thought I’d mention two good experiences.

I was doing a bit of research for a potential project at work and I needed some statistics on businesses in Ireland. I went to the CSO’s online information request and got a response a couple of hours later. They didn’t have the information I needed but suggested a contact in the Revenue Commissioners.

I mailed Revenue then and got a very helpful call back this morning (less the three working hours later) with the information I asked for as well as some additional information to help me better understand the information behind the figures.

Database Design for Doctrine

Creating a database schema directly in the database or in YAML can be very frustrating and difficult. I’ve looked at tools like MySQL Workbench in the paste and have not been impressed – especially as I need an export to YAML function for Doctrine (a PHP ORM project which I’m a big fan of).

I recently came across ORM Designer and have quickly become a big fan. It’s interface is nice, it has excellent support for Doctrine including behaviors and I’ve ran through many update / export to YAML / create models from YAML cycles without issue.

I’d strongly recommend for anyone using Doctrine – plus there’s a 30 day evaluation without any limiting of functionality so you can examine it for yourselves.

Testing SPAM and Virus Filters

I’ve recently performed a complete upgrade of Open Solutions’ mail servers and I’ve now moved onto doing likewise for one of our ISP customers with a lot of users.

These retrofits include installing virus and SPAM filters to protect both ourselves and the ISP customers but also to stop customers who have infected computers from spewing these emails out.

When everything’s up and appears to be working, I like to test both filtering systems to ensure they’re working. Quoting from eicar:

Using real viruses for testing in the real world is rather like setting fire to the dustbin in your office to see whether the smoke detector is working. Such a test will give meaningful results, but with unappealing, unacceptable risks.

Fortunately, test files exist for virus checkers and SpamAssassin:

  • The EICAR standard anti-virus test file can be found here.
  • SpamAssassin created the GTUBE (Generic Test for Unsolicited Bulk Email) for the same purpose and this can be found here.

We’re Now Available Over IPv6!

You probably won’t have noticed but this site is now available over IPv6:

$ host www.barryodonovan.com
www.barryodonovan.com has address 87.232.16.35
www.barryodonovan.com has IPv6 address 2a01:268:3002::35

I spend a lot of my working hours doing a lot with IPv6 and, as any sys admin knows, it’s quite often the case that you get around to doing these things for yourself last. In our case, there was a bit of work involved as we had to first get our ISP’s core network dual stacked with IPv6 – luckily they’re a customer of ours 😉

Stay tuned here and over on the company blog for upcoming IPv6 posts and announcements.

In the meantime, if your ISP isn’t offering IPv6 to end users yet, head on over to SixXS where you can get an IPv6 tunnel for free. If you’re based in Ireland be sure to chose HEAnet or Airwire as your PoP as they’re both based in Ireland and members of INEX so your latency will be as low as possible.

UPDATE: Much more on this an why over on the company blog: We’re IPv6 Ready – Finally!