About Jay Jay

Hi there. My name is John Elliot V. My friends call me Jay Jay. I talk about technology on my blog at blog.jj5.net and make videos about electronics on my YouTube channel @InTheLabWithJayJay.

Configuring bind for LAN PTR records

Posted on 2012-02-13 [Monday] by Jay Jay

I have a hosts file that defines IP addresses on the LAN for all of my virtual hosts. The good thing about using the LAN IP addresses for inter-host communication is that it’s free bandwidth. I had a problem with Postfix though, because Postfix does a reverse lookup on IP addresses to get the corresponding hostname, and the IP address Postfix has for local addresses is the LAN IP address, not the public IP address. The public IP addresses are configured with proper reverse DNS PTR records, but the local addresses weren’t. So I decided to fix that.

Basically I installed bind and configured it with PTR records for the 10.0.0.0/8 network. Now when Postfix asks for the RDNS of a LAN IP address it should get the corresponding hostname. I didn’t need to configure bind with zones for the local IP addresses, because those are all specified in my /etc/hosts file. At least I hope I don’t have to configure DNS zones for my local IP addresses in bind, because that’d just be a pain in the arse.

INFO: task dpkg:27497 blocked for more than 120 seconds.

Posted on 2012-02-11 [Saturday] by Jay Jay

I’ve been getting this error from time to time on my Ubuntu server:

 INFO: task dpkg:27497 blocked for more than 120 seconds.

I did some research and it turns out this is related to a bug in the dpkg system, and apparently it’s been fixed already (but not rolled out as part of Ubuntu yet).

Look forward to the fixed being rolled out, because the implication of the bug at the moment is that my system can hang for long periods of time while I’m installing software with apt-get.

Apache 2 with SSL/TLS: Step-by-Step

Posted on 2012-02-09 [Thursday] by Jay Jay

Reading a series of articles, Apache 2 with SSL/TLS: Step-by-Step:

I’ve done all this before. Just checking if I’ve missed anything. Might have a play with client certificates. Haven’t used them before.

Postfix Virtual Mailboxes and Procmail Filtering

Posted on 2012-02-09 [Thursday] by Jay Jay

Am interested in getting procmail to work with my Postfix/Courier setup. Am using virtual domains/aliases/mailboxes stored in a MySQL database and a Maildir file system. Have only just begun my investigations. So far I’ve found:

Security considerations for find

Posted on 2012-02-09 [Thursday] by Jay Jay

Read about the security considerations for find. Find is a *nix tool for searching though directories for files and filtering them to build lists or run commands.

While I’m here I might as well show you my latest find command, I think it’s a beauty. :)

sudo find . \
  \( \( \( \! -user jj5 \) -or \( \! -group jj5 \) \) \
    -execdir chown jj5:jj5 '{}' \+ \) , \
  \( \( -type d \( \! -perm -u+rwx \) \) \
    -execdir chmod u+rwx '{}' \+ \) , \
  \( \( -type f \( \! -perm -u+rw \) \) \
    -execdir chmod u+rw '{}' \+ \)