While working with projects managed by maven you could run into issues where you have to disconnect your development environment from the internet and continue to work on the code. The experience i had was i had to debug a system deployed to a customer network which had no internet access. I suddenly realized my development environment on my laptop was completely useless. Pretty bad when there are people standing behind you and waiting for you to resolve their problem.
The solution is downloading the maven dependencies to your local by executing below command from the same directory where your pom file is located.
[rozaydin@RO]$ mvn dependency:go-offline
Maven will download all dependencies your project needs and you could be able to continue working with no need to internet access.