I work in a small product company. I am part of team of size 4 that is building a deployment pipeline for our product
My company has also hired a freelance devops consultant who helps us in managing our CI/CD platform. This guy has around 15 years of experience and is a hothead and i don't trust him.
We use jenkins CI\CD tool and have installed it on an aws ec2 instance. All the my team mates and the devops consultant has root access to the ec2 instance.
Today at 11 am suddenly jenkins UI stopped working. It was loading really slow. We restarted jenkins, increased heap size and everything we could think of, but were not able to find a solution.
We spend around 3 to 4 hours trying to debug the problem, Suddenly this guy (devops consultant) came and fixed the problem in 5 min. When i asked him what did he did, He said he removed some temp files. Being sceptical I immediately went and checked the command history
He ran following commands
8 tc qdisc del dev eth0 root
229 tc qdisc del dev lo
230 tc qdisc ls
231 tc qdisc del dev lo root
232 echo -n "CPU" "100 99 166"
233 echo -n "CPU" -n "100 190 188" -n
234 yc qdisc del dev eth0 root
235 tc qdisc del dev eth0 root
236 tc qdisc del eth0
237 ifconfig
238 tc qdisc del eth0 root
239 tc qdisc del eth0 root 1
240 tc qdisc del dev eth0 root
241 at now +38 minutes
I did a quick google search and found that tc command is used for traffic control. It is used to simulate latency in network by inducing delay or packet loss
From the above commands its looks like he deleted some rules which were causing packet loss or delay in outgoing packets.
What i understand is this guy added some rules using tc command which caused delay or packet loss because which our jenkins UI was not loading and then deleted those rules which fixed the problem.
I am a developer and have little experience in system administration and devops. Can somebody confirm this so that i can go to management and lodge a formal complaint.