How to create Generic Object Pool in Java
In a application you can have resources that are limited or time consuming to create a new one. e.g. a connection to a database, a new thread. A solution is to create a the limited resource once and reuse it. To address this problem the object pool pattern was introduced. The object pool design will have the mechanism to create a new object to keep the objects and to destroy the objects if necessary.
Change ssh default port in Linux
By default, ssh listens for incoming connections on port 22. So if a hacker wants to attack your machine he will most likely scan port 22 first. Just to make an idea how important is this (from my point of view of course), before changing the default ssh port for my server I got every day 1000+ login tries for my root user. An effective (but minimal) method to protect your machine is to run ssh on non-standard port. Any unused port will work but one above 1024 is preferable.
