IkerLuengo

We were able to reproduce the issue regarding the communication between multiple users. However, we didn't find any difference with the network connection up or down. Since Foxy, FastDDS includes...

To give some context, this proposal was discussed an approved on the @ros2/security_working_group on June ([minutes here](https://github.com/ros-security/community/pull/21/files/32c36a3edd325f13161fb63d56aa43e0bc52df87?short_path=9cda9df#diff-9cda9df9da4cc61bc08a97de404c6ac72d258c1eeca3eb5ae8459d16c23002ce), although with Sid gone, they are still unmerged).

Corrected as per suggestions from @hidmic

Modified as suggested by @hidmic.

We have done the design to address the problem with the service discovery. You can find it documented on PR #418

It would be interesting to analyze why the partial coverage lines are fully covered for the `PARTICIPANT`, `DATAREADER`, `DATAWRITER` and `LOCATOR` cases, and not the others. That could give us...