When I run IntelliJ IDEA 2021.1.2 (Ultimate or Community edition) on macOS, I observe that 3 random ports are open on all network interfaces (eth0, lo, ...). One random port is open by the idea process and the two other ports are open by a different java process launched by IntelliJ IDEA.
I've removed the only plugin I've explicitly installed which is SonarLint.
The debugger which is running on port 63342 is bind to localhost and this can be configured in the Preferences menu.
Here is the relevant part of the output of lsof -i | grep LISTEN
:
idea 3328 orto 187u IPv4 0x3c332685aa6872fd 0t0 TCP localhost:6942 (LISTEN)
idea 3328 orto 686u IPv4 0x3c332685aa623815 0t0 TCP localhost:63342 (LISTEN)
idea 3328 orto 752u IPv4 0x3c332685aa676de5 0t0 TCP *:53212 (LISTEN)
java 3341 orto 33u IPv6 0x3c332685aa5f899d 0t0 TCP *:61070 (LISTEN)
java 3341 orto 77u IPv6 0x3c332685b9885edd 0t0 TCP *:53210 (LISTEN)
As asked, here is the relevant part of ps -ef | grep 3341
(it's a RemoteMavenServer):
/Applications/IntelliJ IDEA.app/Contents/jdk/Contents/Home/jre/bin/java -d64 -Djava.awt.headless=true -Didea.version==2017.1.1 -Xmx768m -Didea.maven.embedder.version=3.3.9 -Dfile.encoding=UTF-8 -classpath /Applications/IntelliJ IDEA.app/Contents/lib/resources_en.jar:/Applications/IntelliJ IDEA.app/Contents/lib/log4j.jar:/Applications/IntelliJ IDEA.app/Contents/lib/snappy-in-java-0.5.1.jar:/Applications/IntelliJ IDEA.app/Contents/lib/jna.jar:/Applications/IntelliJ IDEA.app/Contents/lib/jna-platform.jar:/Applications/IntelliJ IDEA.app/Contents/lib/annotations.jar:/Applications/IntelliJ IDEA.app/Contents/lib/oromatcher.jar:/Applications/IntelliJ IDEA.app/Contents/lib/trove4j.jar:/Applications/IntelliJ IDEA.app/Contents/lib/util.jar:/Applications/IntelliJ IDEA.app/Contents/lib/jdom.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/lucene-core-2.4.1.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven-server-api.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3-server-common.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3-server-lib/archetype-catalog-2.2.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3-server-lib/archetype-common-2.2.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3-server-lib/maven-dependency-tree-1.2.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3-server-lib/nexus-indexer-3.0.4.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3-server-lib/nexus-indexer-artifact-1.0.1.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3-server-impl.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/aether-api-1.0.2.v20150114.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/aether-connector-basic-1.0.2.v20150114.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/aether-impl-1.0.2.v20150114.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/aether-spi-1.0.2.v20150114.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/aether-transport-wagon-1.0.2.v20150114.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/aether-util-1.0.2.v20150114.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/aopalliance-1.0.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/cdi-api-1.0.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/commons-cli-1.2.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/commons-io-2.2.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/commons-lang-2.6.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/commons-lang3-3.4.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/guava-18.0.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/guice-4.0-no_aop.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/javax.inject-1.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/jsoup-1.7.2.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/jsr250-api-1.0.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-aether-provider-3.3.9.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-artifact-3.3.9.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-builder-support-3.3.9.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-compat-3.3.9.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-core-3.3.9.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-embedder-3.3.9.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-model-3.3.9.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-model-builder-3.3.9.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-plugin-api-3.3.9.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-repository-metadata-3.3.9.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-settings-3.3.9.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-settings-builder-3.3.9.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/org.eclipse.sisu.inject-0.3.2.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/org.eclipse.sisu.plexus-0.3.2.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/plexus-cipher-1.7.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/plexus-component-annotations-1.6.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/plexus-interpolation-1.21.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/plexus-sec-dispatcher-1.3.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/plexus-utils-3.0.22.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/slf4j-api-1.7.5.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/slf4j-simple-1.7.5.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/wagon-file-2.10.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/wagon-http-2.10-shaded.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/wagon-http-shared-2.10.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/lib/wagon-provider-api-2.10.jar:/Applications/IntelliJ IDEA.app/Contents/plugins/maven/lib/maven3/boot/plexus-classworlds-2.5.2.jar org.jetbrains.idea.maven.server.RemoteMavenServer
How to bind these three random open ports to localhost?
Notes
== Update 28 March 2023 ==
With IntelliJ 2022.3.3 (Ultimate Edition), I have no more TCP ports bound to the wildcard interface. But two UDP ports are still bound to the wildcard interface as in the screenshot of the CrazyCoder answer.
== Update 3 september 2024 ==
With IntelliJ IDEA 2024.2.1 (Ultimate Edition), UDP ports 8976 and 58486 are still open, by default, on the IPV6 wildcard interface.
IntelliJ IDEA doesn't bind any ports on the wildcard interface by default, except for the UDP concurrent licensing check (only for Ultimate). All the ports used for internal needs (Netty library initialization, exclusive folders lock, built-in web server, debugger, compiler/maven/gradle/running process IPC) are open on the localhost
(127.0.0.1
) interface: