Hey there, welcome back to another blog post. In this one, I will document my experience in implementing TLSv1.3 to Nagios Remote Plugin Executor (NRPE) for the IETF 102 Hackathon. Rahul and I paired up for this task. In the last hackathon, he implemented TLS 1.3 in the check_http Nagios plugin ( PR#368 ) and was quite familiar with Nagios already. What are Nagios and NRPE ? In short, Nagios monitors systems, networks and infrastructure. It alerts users when things go wrong and warn them again when the problem has been resolved. NRPE, as the name tells, allows the user to be able to execute Nagios Plugins remotely. The encryption part between check_nrpe and NRPE security protocol could only support up to TLSv1.2. How we made it? On the first day, we quickly set up our virtual machines, cloning the NRPE repo and going through the code. Everything went fine. The testing part was a little bit more tricky but at the end, we made it through even if Rahul was pretty sick.