This morning when accessing YouTube from TV, there’s no response. Found that the reason was internet access failure though WiFi connection was fine.

Then some other things got wrong due to router issue.

Issue

All the web hosting sites in local virtual server were down. The problem was port forwarding records all disappeared. I guess that after rebooting the router some configuration was corrupted.

Even worse, once adding back those port forwarding records, there’s error message about something like IP conflicts.

Solution

Restore previous configuration backup

Tricks

Sometimes a buggy device is bad. This time there are double bugs. First, configuration settings (port forwarding) unexpectedly corrupted; then the previous port forwarding became zombie configuration records. New addition of settings create conflicts.

Configuration

Netgear Nighthawk MR60: firmware ver. 1.0.4.98

The post Port Forwarding Issue – Netgear Nighthawk appeared first on LarryLai.

When trying to use FaceTime on iMac to make phone calls through iPhone, there is an issue to connect the iPhone with the Mac. Even though these 2 devices are on the same WiFi network. There’s an error message on the iPhone “Cannot turn on calls on other devices”. When clicking “Calls on Other Devices” under “Settings -> phone” as suggested by Apple’s support forum, it doesn’t work to connect the iPhone with the Mac.

Solution:

In the iPhone, go to Settings, and click “facetime”, select something like … AppleID… and sign in.

Tricks:

Though the AppleID is signed in probably in my new iPhone, some Apps have to be signed in, I guess, before some of its features are to be enabled.

Config:

• iPhone SE 2020: iOS 13.5.1
• iMac (late 2013): macOS 10.15.5 (Catalina)

The post Make Phone Calls on Mac appeared first on LarryLai.

Google Site Kit plugin for WordPress is no doubt a comprehensive site performance plugin delivering promised all-in-one dashboard also with colourful layout.

Issue:

Using Google Site Kits plugin for a while without problem, suddenly its dashboard, settings, analytics, etc. all go blank.

Solution:

Disable the plugin – Remove Query Strings by Littlebizzy

Tricks:

• A common practice to solve this kind of problem is to disable all plugins. However, in some cases with CDN installed like CloudFlare plugin, the DNS of the website is usually switched from domain hosting company to the CDN. Then, once the plugin is disabled, the website address will be disconnected with your web hosting server.
• The ‘Remove Query Strings’ plugin is to improve website speed rating.

The post Google Site Kit All Blank in WP appeared first on LarryLai.

Solution

1. 1. Remove the symbolic link of privkey.pem under

      /etc/letsencrypt/live/[mydomain]/privkey.pem

   2. recreate the symbolic link with the dedicated user running Jupyter notebook.
   3. Run command as root:

      systemctl restart jupyterhub

Tricks

1. 1. • As the jupyter server is run by the ownership of a dedicated user, after the renewal, the private key, i.e. privkey.pem must be owned by this user. However, I run the command:

        certbot renew --standalone

        under root.

      • note that let’s encrypt command for CentOS 6 is quite different from CentOS7

Config

1. • OS: CentOS 7
   • Jupyter-notebook: 5.7.8

The post SSL Key Ownership appeared first on LarryLai.

Default ordered list item style is decimal number, lower/upper alpha, lower/upper roman then followed by a dot. Thought it’s easy to change the dot to something like
  a) This is good 1st item
  b) This is good 2nd item.

      instead of:
  a. This is not good 1st item
  b. This is not good 2nd item

However, there’s no simple way to change the style of ordered list item and remove the dot after the order number <ol> <li></li></ol>.
As I got used to markdown’s convinence of auto numbering for ordered list items, don’t want to hard code the order into the list.

Solution

1. Removing the default ordering number and using counter by creating counter variable (say, list) like this
     ol { list-style-type: none; counter-reset: list;}
2. Update counter variable for each \
3. like this `ol>li { counter-increment: list; }
4. Display the content of the new counter like this `ol>li::before { content: counter(list, lower-alpha) ") "; }

Tricks

• It’s a bit complex for multi-level ordered list, but the principle still applies
• Some more has to be added to see hanging text like default ordered list display. This can be done by the following for modifying 2nd order level :

  ol ol {    
    list-style-type: none;    
    counter-reset: list;   
  }     
  ol ol>li::before {     
    content: counter(list, lower-alpha) ") \00a0";
    display: inline-block;
    width: 1.5em;
    text-align: right;
  }    
  ol ol>li {    
    counter-increment: list;    
    margin-left: .5em;    
    text-indent: -1.5em;    
  } 
  

  Of course, several paramenters can be adjusted to fit into each individual case. These include margin-left, text-indent spaces and the counter number style, i.e. lower-alpha, lower-roman, decimal, etc.

The post CSS List item style a) b) appeared first on LarryLai.

Solution

• In the setting of the plugin, choose the tab Additional Firewall Rules
• Uncheck the option at the bottom, i.e. Advanced Character String Filter

Config

• WordPress 5.3
• All In One WP Security v4.4.2
• MathJax-LaTex v1.3.11

The post MathJax Load Failed – WP Security Plugin appeared first on LarryLai.

Issue
Water could barely be diverted to the shower after pulling the diverter knob, but aside from this malfunctioning the bath shower mixer is still in good condition.

Solution
Purchase the appropriate diverter from a building material store, Luen Hing Hong Building Materials Ltd. in Portland St., Mongkok. The replace it on my own according to the instruction given by the sales of the store.

Tricks

1. The video footing about replacement of bath/shower diverter for other brands is totally irrelevant to this model Grohe 33485.
2. Neither pliers nor adjustable spanner wrench can help to remove the parts as the inside material of the knob is rubber-like material, i.e. not rigid. Only 6 point combination wrench with size 11/16 can do the trick.

The post Grohe Bath/Shower Mixer Diverter Replacement appeared first on LarryLai.

VirtualBox client CentOS can’t boot up with error message:

1. [FAILED] Failed to start Virtual Machine and Container Registration Service.
2. [FAILED] Failed to start Login Service.
   

Solution

Disable SELINUX config with the following steps during boot up sequence:

1. During Grub boot up stage, press 'e' to edit grub sequence;
2. Add systemd.unit=rescue.target to the end of line with linux16 and boot with rescue mode;
3. Press ctrl+x to continue boot sequence

Config

• CentOS 7 3.10
• VirtualBox 6.0.10

Tricks

• The cause of this boot up issue was difficult to found and the original setting of SELINUX was ‘permissive’ not ‘enabled’. However, this issue may also be owing to bugs in VirtualBox 6.
• During boot up process, by default the boot up is quiet, i.e. no system message will be displayed, only the boot up progress bar is seen. However, pressing Esc key will let you see the detail boot up messages.

The post CentOS VM Client Can’t Boot Up appeared first on LarryLai.

Solution
Be sure that jupyter-notebook is used instead of jupyter notebook, i.e.
ExecStart=/[pathOfTheBinary]/jupyter-notebook
or else it should be bracketed with quotation marks to ensure the space between jupyter and notebook is allowed.

Tricks

• Be sure that the path of the jupyter binary is correct
• Most of the info. on the web suggesting the content of jupyter.service file missed the fact that jupyter notebook is recommended to be run by non-root user, and it’s imperative that the location of jupyter configuration file must be specified in the jupyter.service file and not just the User=[jupyterUser] directive.

Config

• CentOS: 7-6
• jupyter: Anaconda3-5

The post Jupyter Notebook on Boot Automatically appeared first on LarryLai.

After installing a WordPress plugin – WP Health, it’s reminded that PHP5 had no longer been supported since late 2018, thus there may be risk in all WordPress websites.

Issue

Since removing PHP5 (retrospectively known that it’s not necessary), and installed remi’s repository’s PHP72, some WordPress sites could not be accessed with message: “Internal Server Error. The server encountered an internal error or misconfiguration and was unable to complete your request.” Then using VirtualBox’s snapshot to roll back and finally got every site back to normal.

However, using re-check configuration of Virtualmin to see if there’s anything need to follow up, it’s known that mod_actions of Apache wasn’t enabled. Then after enabling mod_actions by uncommenting the following:

LoadModule actions_module modules/mod_action.so

in /etc/httpd/conf.modules.d/00-base.conf, something weird that instead of executing php page, these pages were downloaded. Some members on forums suggested that the following in /etc/httpd/conf.d/php.conf should be commented out:

SetHandler application/x-httpd-php

This really solved the problem of not executing php pages, but another weird thing happened. Some other websites couldn’t be accessed again with message: 500 Internal Server Error.

Solution

1. The permission of some html directories all granted to 775 and changed owner as apache.
2. In Virtualmin, Server Config -> Website Options -> PHP script execution mode must select FPM if mod_fpm is installed and enable.

Tricks

Before comment out SetHandler application/x-httpd-php, directory permission was not a problem. What and how does something change the permission or why is the permission of html directories should be further granted to eliminated 500 Internal Server Error?

Config

• WordPress 5.1
• Virtualmin 6
• PHP7.2 remi
• CentOS7

The post PHP 7 & Related Issues appeared first on LarryLai.