Disable udp ports for Jenkins
I’ve noticed that Jenkins has an unpleasant habit to listen on two UDP ports (5353 and 33848) on all interfaces even if it was told to listen on 127.0.0.1:8080.
These ports are for UDP multicast broadcast. You may not need either of them, and you can disable them by adding the following options:
java -Dhudson.DNSMultiCast.disabled=true -Dhudson.udp=-1 -jar jenkins.war –httpListenAddress=127.0.0.1 –httpPort=8080 –daemon –logfile=/home/jenkins/jenkins.log
See the Jenkins docs for more https://wiki.jenkins.io/display/JENKINS/Features+controlled+by+system+properties