It seems by default CentOS doesn’t allow network be accessed from outside. Here are the instructions how to make it work on CentOS 7. From here and here.

Today I got an error when running a Java application on a new CentOS server:

1

SunCertPathBuilderException: unable to find valid certification path to requested target

Here is the solution.

From here and here.

When I’m writting an Spring Boot command line application and I find this issue. Here is how I solve it.

The question is straightforward. The solution is from here.

Recently I upgraded a computer from Ubuntu 16.04 to 18.04. Then I found when I closed the lid, the notebook computer would go to sleep. Here is the instructions from here how to disable the auto-sleep feature.

From “here“ and “here“.

From here.