John Kawakami's blog

Note on Migrating from Qmail to Postfix

I got this done (i think):
- scanning old email addresses, forwards, and lists, and reconstructing the email and forwards and aliases for lists on a postfix instance

Migrating with Data...

It's one thing to upgrade software. It's an entirely different thing to migrate to new software. If you have a whole system of software, integrated in to a mega-app, it's even more difficult.

Script to Compile Videos from JPGs Uploaded from Low-End IP Camera DLINK DCS-932L

This script uses ImageMagick and AVConc (ffmpeg) to convert images uploaded by a low-end DLINK internet camera to an FTP server.

D-Link Switch Power Adapter Barrel Size

I had a couple of these, and lost the power adapters. (OK, someone else lost them, but whatever.) As always, the voltage and current matter, and these guys use 5V 1.2A or 2A.

Discover the IP Address of a Cisco Aironet 1200 Series on Linux without IPSU

I got an Aironet 1200 and didn't have the serial cable, so I tried to use IPSU to find the IP address. I ran it in a VM, bridged the ethernet interface, and it failed.

How to Install Postfix on Ubuntu

(argh, forgot to back up my postfix work. i have to start fresh, so this is an opportunity to document work.)

# first get a superuser shell with sudo
sudo -s

apt-get install mailutils
apt-get install postfix
apt-get install mailman
apt-get install spamassassin
apt-get install courier-imap
apt-get install courier-imap-ssl
apt-get install courier-pop
apt-get install courier-pop-ssl

# unfortunately, we need to install apache2 because we're going to install
# the roundcube mail client

apt-get install apache2
apt-get install roundcube

One-Liner to Install Java JDK into /usr/local/bin

There's a zillion ways to do it, and editing $PATH is probably the best, but I didn't want to do that, so I did this:

for i in ` ls /usr/local/java/jdk1.7.0_21/bin/ ` ; do echo $i ; ln -sf /usr/local/java/jdk1.7.0_21/bin/$i $i ; done

That symlinks all the stuff in bin into /usr/local/bin, which is already in the $PATH.

Serve a Stream from a Webcam by Bypassing a Password with a Proxy

This is a one-line trick to serve images from a password-protected webcam to the world.

curl -i http://admin:@ | nc -lCt localhost 10203

My webcam doesn't have a password, but it could. What this does is use curl to get the stream, and then use nc to serve it to a client.

NAS Backup Awesomeness

We have this old Terastation NAS, and it's been solid, but I just figured out that it has support for an external USB disk, and it's easy to set up to backup to the external USB disk. Right now, we're using around 1TB of the array, and it's being backed up to the external disk once a day. The backup is done with Rsync, and it takes around 10 minutes.

Cloud Computing Costs

I was checking out cloud services a year ago, and pricing them out. The general rule of thumb seemed to be that the up-front costs were lower, but the cost over time was higher. The ongoing costs generally work out to around $60 to $500 per application per user per year.

A typical situation is buying 25 Exchange mailboxes for $5 per month. That's $1,800 per year. That's cheaper than buying a server and Exchange, but not necessarily if you factor in other services running on your hardware.

Photo Wall that Scrolls Forever Loading New Photos at Bottom

I was reading the code at and learned how to do this "scrolling forever wall" effect. It's clever.

Deliverability Blues 2013

We recently had a rash of spam sending due to someone finding, guessing, or leaking a user's password. Sometimes, it just requires that, not some security breach. Well, we didn't catch it and stop it in time, and now we're suffering some deliverability problems ranging from slowdowns to outright blocking by some servers.

Sign in sheet website

I spent way too much time tonight putting together a sign-in sheet website, called, generically enough Sign-in Sheet.

Computer Professional Overtime Exemption

Under US labor rules, some computer programmers are exempt from overtime laws. There is considerable misunderstanding about this law. I'm not an expert, or even novice, about this law, but am compiling this page as a resource for study and to increase understanding. Corrections to johnk-at-riceball-dot-com are appreciated. If you would like to network and get on a mailing list about this issue, please write to that address as well.

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