How to turn off Facebook’s “Do you know so-and-so” (and other) notifications on Android

  1. Open the Facebook app
  2. Click on the hamburger button (displayed as ≡) near the top-right corner of screen
  3. Scroll down and tap on Account Settings > Notifications
  4. Under the “How You Get Notifications” section, select “Mobile”
  5. Tap on the notifications that you want to turn off



印順法師《般若經講記》 (Source)




昭慧法師 · 無常、無我,大悲、大願——佛指舍利的啟發 (Source)

How to disable accidental keyboard input in a Linux terminal

Sometimes I type in the wrong window in a multi-monitor setup without knowing and end up spamming WeeChat IRC.

To prevent that, I now use gnome-terminal and turn on “Read-Only” mode. This useful feature is, however, not available in other terminals. Please share in the comments if you know of alternatives.

WOT probes my web access history

I loaded a private web address using Chromium with the extension WOT v2.6.0 (by www [dot] mywot [dot] com).

Hours later, some unknown IP probed my private address.

I repeated the same test with another unique private URL, and hours later, the same ec2 IP loaded that private URL again.

Then I disabled the WOT extension in Chromium and repeated the same test with a new unique private URL. No more probes.

Bad WOT! You should just be checking whether a link has bad reputation instead of loading the web addresses I’ve visited.


How to change sshd default port on firewalld


Instead of messing around with the ports directly with RHEL7/CentOS7 firewall-cmd, I’ve decided to update the port number in the ssh.xml service file instead. Think it’s cleaner this way.

For example, here are the steps to change sshd port from the default 22 to 9876:

1. Make a copy of the default ssh service file:
cp /usr/lib/firewalld/services/ssh.xml /etc/firewalld/services/

2. Inspect current firewall settings
iptables -nL | grep -e 22 -e 9876
ACCEPT     tcp  —              tcp dpt:22 ctstate NEW

3. Edit /etc/firewalld/services/ssh.xml to change port number
From: <port protocol=”tcp” port=”22″/>
To: <port protocol=”tcp” port=”9876″/>

4. Change /etc/ssh/sshd_config port to 9876

5. Restart sshd
systemctl restart sshd

6. Notice that sshd now listens on new port
netstat -punta

7. Reload firewalld, which will pick up the new port in ssh.xml
firewall-cmd –reload

8. Inspect new firewall settings, notice port changed
iptables -nL | grep -e 22 -e 9876
ACCEPT     tcp  —              tcp dpt:9876 ctstate NEW

9. Test

Cannot download HP printer driver using Chromium/Firefox on Linux

Problem: Somehow the “Software & Drivers” option does not show up when I try to download the printer driver of HP LaserJet Pro MFP M127fn from the official HP website using Chromium, Firefox, Opera and most web browsers on Linux.

Solution: Use Konqueror on Linux or another OS.