I am using Fail2Ban for around 12 years now, maybe more. It started back when ssh brute-forcing script kiddies were everywhere. Who are they? They are people or machines scanning all IPs on the internet, and if they find an open SSH port, they start doing brute force password attacks. They do this for MySQL, PostgreSQL, or basically any open port. If there is a possibility of username/password login, someone will try to get in. ...

Today I needed to check which ports are open on a remote server to ensure that the services I need are running and accessible. Here are a few ways to check which ports are open on a remote server: Telnet Telnet is a command-line tool that can be used to check if a port is open on a remote server. You can use the following command to check if a port is open: ...

When building Spring Boot applications, handling concurrent API calls efficiently is crucial to ensure optimal performance and scalability. Here are a few approaches to manage concurrent read and write operations: Handling Concurrent Read API Calls Asynchronous Methods Using @Async at @Service annotation and enabling asynchronous processing can help handle multiple API calls concurrently. @Async public CompletableFuture<String> asyncMethod() { // Call external API return CompletableFuture.completedFuture("Result"); } WebClient with Reactor Spring WebFlux’s WebClient allows for reactive programming, making it easier to handle multiple API calls. ...

Fine tuning and optimizing the fill factor in PostgreSQL can significantly impact the performance of your database. The fill factor is a parameter that determines the percentage of a data page to be filled with rows, leaving space for future updates to minimize page splits and improve performance on frequently updated tables. By adjusting the fill factor, you can optimize storage efficiency and reduce the overhead of page splits. To fine-tune the fillfactor for tables and indexes, consider the following: ...

Fillfactor in PostgreSQL is a parameter that sets the percentage of a data page to be filled with rows, leaving space for future updates to minimize page splits and improve performance on frequently updated tables. If you are having a table with a lot of updates, you can set the fillfactor to a lower value to leave space for future updates. The default fillfactor is 100, which means that the table is completely packed with rows. ...