tzlee.com/blog

  • What do we plan for?

    What do we plan for?

    Life… can be unpredictable. We make plans, we make decisions. How do we know if they were for the better?

    Only time will tell.

    Most people plan financially. It’s hard to admit it, but it’s probably the only thing we have ever really spent time planning for. How many people make more plans for their health or family than their finances? Not many. Not yet. Not at my age I don’t think.

    As age passes, I realize how important it is to spend more time with family. And also friends, of course. When I got married and bought my HDB as a young teenager, I couldn’t wait to get out of my parent’s house. I mean, every kid does, right? Parents are naggy and annoying. But ever since I had a kid, I went home every weekend so that my parents could see the little one, and it is also sort of a childcare break for me and wife. November 2015, grandma passed away. Towards the end of 2016, my dad had a pretty big heart op, and that’s when I start to realize, hey this man is getting old. You know, there’s only 52 weekends in a year.

    —

    Money is evil. It really is. People get obsessed with it. I’m no saint either. You get some, you want more. You get more, you want even more. People spend a lifetime in search of more money. But, really, money is just an enabler. Once there’s enough to go around, the excess is just… really… excess.

    I know it’s easy to say that once we actually have money. And when we don’t, shit goes bad pretty quickly. We spend all our time trying to fix the lack of it. We get so absorbed into it that at a certain point, amongst the chaos, we will most certainly make bad decisions. That’s why the rich gets richer, and poor gets poorer.

    So I spent the last two years chasing after money — not for me, but for the company. Across my desk are two colleagues… well, friends. Old friends. Both whom I’ve asked to join the company because I thought I saw a better future for them and I believed they could do better. I’m no Bill Gates. I can’t change a million starving kids’ lives. But maybe I can help those around me.

    After years operating as a cost center, salaries have been pretty stagnant. We didn’t really pay very well to start with. I don’t want them to feel like I dragged them from one shithole to another shithole. They both have kids, and I know it’s not easy. It’s about time to turn over some profits.

    Those who know me know I hate doing sales. I’m no sales guy. I’m too honest. Too practical. Too straightforward. I can’t say yes to shit and then let the money do the talking. I hate clicking through shitty-ass bidding sites. I hate writing proposals. I hate doing cost calculations and currency conversions. I hate Microsoft Word, Excel and Powerpoint. I hate sitting in a room with pointy-haired bosses “talking business” for hours. I irritate the shit out of sales people too, because I tell people their shit sucks when it really does. That’s why I am a techie. But I did it anyway and took it as a challenge. I will be lying if I said I haven’t learnt anything new.

    So, we tried to be profitable for about 2 years, maybe coming 3 years. Then comes the 2017 year end review: It wasn’t too good. So-so. We tried our best, we won some, we lost some. But the good news is that there’s finally some money to go around for bonuses and pay raises. As the local “boss”, I had the discretion to allocate… as much as I wanted to myself! Haha.

    Nah, I did not. I gave out most of the allocated budget. I believe that the extra money would take some distraction off them, so that they can focus on work, family and friends. I know money is evil, so I try not to make it evil.

    Did this silly idea of mine really help them? Or maybe they were better off doing what they used to do? Only time will tell, I guess.

  • Where is COE headed in 2018?

    Where is COE headed in 2018?

    Several car salesman told me: “Next year price will go up! Buy NOW!”

    Well done. All the fear mongering will actually lead to a COE plunge. There was a run up prior to the end of this year because of all the panic buying, then it will stop as people adopt a wait-and-see attitude. By then, the car salespeople will tell you that COE is low, and it is the best time to buy. No matter COE high or low, they will spin a story to sell their cars.

    My guess is that sometime in Q1’18 will be the best time to renew COE, where it should plunge back to $40K or even $30K+ levels (for Category A).

    Yes, the new Euro 6 CEVS will affect car prices, but the market will adapt. It’s not like this is the first time the Government has introduced changes to CEVS or COE (e.g. the horsepower categorisation). Eventually the whole system will net itself to zero, i.e. COE drops + CEVS goes up. Car prices will probably just remain the same, and for a while until manufactures catch up with Euro 6, then the regulations will likely change again when majority of vehicles qualify for CEVS discounts.

  • Raspberry Pi print server with no server-side driver

    Raspberry Pi print server with no server-side driver

    There are numerous articles which step through how to configure CUPS to turn an RPi into a print server but I bumped into a problem because there are no drivers available for my Brother MFC-7340 printer for ARM (only available for i386) and I was not keen work on the source code/compile/etc.

    The quick fix is to turn it into a RAW (a.k.a. HP JetDirect) print server.

    Install CUPS

    sudo apt-get install cups

    Configure CUPS

    Edit /etc/cups/cupsd.conf.

    Scroll down until you see the Listen configuration directive. Comment it out. This will make CUPS available over the network.

    # Only listen for connections from the local machine
# Listen localhost:631
Port 631

    Look for the <Location /> directive, and add Allow all (or a specific list of IPs, if your local network is not secure) to allow access.

    <Location />
  # Allow remote access...
  Order allow,deny
  Allow all
</Location>

    Save the file and restart CUPS.

    sudo /etc/init.d/cups restart

    Configure Printer

    Now connect your printer to the USB port on the RPi.

    Now you should be able to use a browser and go to https://<ip.address.of.rpi>:631/admin to reach the CUPS web UI.

    1. Under Printers, click Add Printer.
    2. You should see your printer appear under Local Printers. Select it and click Continue.
    3. You can accept the default names on the next screen and click Continue.
      • You do not need to enable Share This Printer.
      • Make a note of the printer Name. You will need this later.
    4. In the next screen, click on Select Another Make/Manufacturer.
      • Select Raw and click Continue.
      • Select Raw Queue (en) and click Add Printer.

    Install xinetd

    sudo apt-get install xinetd

    Configure xinetd

    Edit /etc/services and scroll to the end. Add the following line:

    jetdirect 9100/tcp

    Create a new file /etc/xinetd.d/jetdirect and add the following, replacing Brother_MFC-7340 with your printer name configured in CUPS above.

    service jetdirect
{
socket_type = stream
protocol = tcp
wait = no
user = root
server = /usr/bin/lp
server_args = -d Brother_MFC-7340 -o raw
groups = yes
disable = no
}

    Save the file and restart xinetd.

    sudo /etc/init.d/xinetd restart

    Connect your computer

    Now, go to your computer and connect to the printer. These are steps for Macs.

    • Go to System Preferences > Printers and Scanners.
    • Click on [+] to add a new printer.
    • Select IP
      • Address: <ip.address.of.rpi>
      • Protocol: HP JetDirect
      • Queue: <Blank>
      • Name: Enter a name of your choice here, e.g. Office Printer.
      • Use: Click Select Software and use the correct driver for your printer here.

    You should now be able to print to the new printer on your Mac.

    P.S. Sometimes you may need to connect your printer via USB to your Mac so that it installs the correct drivers first, then you can unplug the USB and select the drivers when configuring IP printers.

  • Telnet missing in macOS 10.13 High Sierra

    Although Telnet is barely used anymore as a remote access protocol/tool, it is still a very popular debugging tool for tech professionals.

    Unfortunately the quick fix here is to use netcat (nc).

    alias telnet nc
  • Flash crashing with vSphere Client, fix for Mac

    Flash crashing with vSphere Client, fix for Mac

    Looks like a new Adobe Flash (a.k.a. Shockwave Flash) update caused widespread panic with users of the web-based flash vSphere Client 6.x leaving them with a “Shockwave Flash has Crashed” message and no vSphere Client. The immediate fix is to downgrade Adobe Flash.

    VMware has released an official KB 2151945 but it only provides instructions for Windows users.

    Here’s how to fix for Mac users

    1. Go to Adobe’s Archived Adobe Flash Player versions page.
    2. Scroll down to Flash Player Archives and download Flash Player 27.0.0.159 (released 10/10/2017) or use this direct link.
    3. Once the package is downloaded it should extract automagically. If it does not, extract it.
    4. Open the folder fp_27 and sub-folder 27_0_r0_159.
    5. Double click uninstall_flashplayer27_0r0_159_mac.dmg to mount the image, and run the Adobe Flash Player Uninstaller. This should uninstall the existing Flash Player on your computer.
    6. You will need to close your browser(s) at this point. Bookmark this page for reference later.

    For users of Firefox

    1. After uninstalling, double click flashplayer27_0r0_159_mac.dmg and then (re)Install Adobe Flash Player. Your browser(s) should still remain closed at this point.
    2. You will be prompted to select how you want Adobe to update Flash. Be sure to select Notify me to install updates.
    3. Unmount the two disk images you mounted earlier.

    For users of Chrome

    1. Delete the current flash version. Open Terminal, and run these commands: 
      cd ~/Library/Application\ Support/Google/Chrome/PepperFlash/
rm -rf 27.0.0.170
    2. Double click flashplayer27_0r0_159_macpep.dmg and then (re)Install Adobe Flash Player.
    3. You will be prompted to select how you want Adobe to update Flash. Be sure to select Notify me to install updates.
    4. Unmount the two disk images you mounted earlier.

    You should now be able to get back to work in VMware vSphere Client. Drop me a note if the instructions do not work for you, I’ll be glad to update the content.

  • Why are multiple subnets needed in vSphere ESXi?

    Why are multiple subnets needed in vSphere ESXi?

    Most know that having different subnets for management traffic, vMotion, storage, etc. is a best practice but some may not understand why.

    Routing 101: Two paths to the same place

    Let’s take for example you have a laptop and is connected to both wifi and LAN at home/office (on the same subnet). Which connection is being used when you browse the Internet or even print to a local network printer?

    The answer is the first connection you are hooked up to, or the more technically correct answer is the route that is of a higher order of preference. When two NICs are connected on the same subnet, your local routing table will have two entries to the directly connected subnet, e.g.

    192.168.1.0/24 via en1 metric 100
192.168.1.0/24 via en0 metric 100

    When a packet is sent (e.g. to your gateway at 192.168.1.1), the operating system will look up the route table and pick the first match, and in this instance it would be en1. Of course if the two routes have different metrics, then the metric of a smaller number gets the preference.

    But if you have both NICs connected to different subnets, e.g.

    192.168.1.0/24 via en1 metric 100
172.16.1.0/24 via en0 metric 100

    Then it becomes clear which path to take when you try to get to your printer at 172.16.1.15 or your NAS at 192.168.1.100.

    The same thing happens when you have two (or more) vmkernel NICs on the same subnet. Separating the subnets will ensure that the desired traffic takes the correct path out.

    Interface binding

    Some may wonder why can’t interface binding be used, similar to running ping -I <intf>? The answer is yes! Interface binding is used for Multi-NIC vMotion (5.1 and newer) and for the Software iSCSI initiator where iSCSI multi-pathing requires two or more different vmknics within the same subnet. But this works only with vMotion, the Software iSCSI initiator, or other specific ESXi services designed to have NIC binding.

    To allow NIC binding to work, the general requirement is that only one active physical NIC can be present in the NIC teaming configuration, e.g.

    // vSwitch setup
vSwitch0 = eth0, eth1
vSwitch1 = eth2, eth3
vSwitch2 = eth4, eth5

// No port binding
vmk0 management 192.168.1.11/24 via vSwitch0 (active: eth0, eth1)
vmk1 iscsi-hb 172.16.1.11/24 via vSwitch1 (active: eth2, eth3)

// Port binding services
vmk2 iscsi-1 172.16.1.12/24 via vSwitch1 (active: eth2, unused: eth3)
vmk3 iscsi-2 172.16.1.13/24 via vSwitch1 (active: eth3, unused: eth2)
vmk4 vmotion-1 172.16.2.11/24 via vSwitch2 (active: eth4, standby: eth5)
vmk5 vmotion-2 172.16.2.12/24 via vSwitch2 (active: eth5, standby: eth4)

    vSphere 5.1 and iSCSI heartbeat

    iSCSI heartbeat which uses regular ICMP ping does not bind to a specific interface prior to vSphere 5.1. Back in the good old days, it was a best practice to create 3 vmknics and leave the vmknic with the lowest index number for iSCSI heartbeat to give it a routing priority. In vSphere 5.1 and later VMware addressed this and made iSCSI heartbeat bind to an interface but there have been reports of it not working as intended.

    vSphere 6.0 and TCP/IP Stacks

    VMware introduced independent routing tables (know as TCP/IP stacks) in vSphere 5.5 but it was cumbersome to configure via CLI. In vSphere 6.0 three different TCP/IP stacks are available by default so that Management, vMotion and Provisioning (cloning, snapshots, etc.) traffic can be configured to route differently. For the Cisco guys this is easily explained as VRF. This introduction allows vMotion and Provisioning traffic to be routed. Although not usually needed, vMotion routing will be required if you want Long Distance vMotion to get across two different (routed) subnets.