Prevent Jenkins access on port 8080

jenkins reverse-proxy

You can use iptables since it's Ubuntu, to block all non-local access to port 8080.

iptables -A INPUT -p tcp --dport 8080 -s localhost -j ACCEPTiptables -A INPUT -p tcp --dport 8080 -j DROP

jenkins reverse-proxy

There is another solution (without the need for IPtables):

Prevent jenkins from being accessed outside of the server in port 8080:
- Edit file /etc/default/jenkins
- AddHTTP_HOST=127.0.0.1
- In the end change the line:
  - From:JENKINS_ARGS="--webroot=/var/cache/$NAME/war --httpPort=$HTTP_PORT"
  - To:JENKINS_ARGS="--webroot=/var/cache/$NAME/war --httpPort=$HTTP_PORT --httpListenAddress=$HTTP_HOST"
- Restart the jenkinssystemctl restart jenkins