title: maven : UnknownHostException: repo.maven.apache.org
body: <p>I am having this maven problem : </p>
  
  <blockquote>
    <p>[ERROR] Plugin org.apache.maven.plugins:maven-resources-plugin:2.6 or one of its dependencies could not be resolved: Failed to read artifact descriptor for org.apache.maven.plugins:maven-resources-plugin:jar:2.6: Could not transfer artifact org.apache.maven.plugins:maven-resources-plugin:pom:2.6 from/to central (<a href="http://repo.maven.apache.org/maven2" rel="nofollow">http://repo.maven.apache.org/maven2</a>): repo.maven.apache.org: Unknown host repo.maven.apache.org -> [Help 1]
    org.apache.maven.plugin.PluginResolutionException: Plugin org.apache.maven.plugins:maven-resources-plugin:2.6 or one of its dependencies could not be resolved: Failed to read artifact descriptor for org.apache.maven.plugins:maven-resources-plugin:jar:2.6
        at org.apache.maven.plugin.internal.DefaultPluginDependenciesResolver.resolve(DefaultPluginDependenciesResolver.java:129)
        at org.apache.maven.plugin.internal.DefaultMavenPluginManager.getPluginDescriptor(DefaultMavenPluginManager.java:142)
        at org.apache.maven.plugin.internal.DefaultMavenPluginManager.getMojoDescriptor(DefaultMavenPluginManager.java:261)
        at org.apache.maven.plugin.DefaultBuildPluginManager.getMojoDescriptor(DefaultBuildPluginManager.java:185)
        at org.apache.maven.lifecycle.internal.DefaultLifecycleExecutionPlanCalculator.setupMojoExecution(DefaultLifecycleExecutionPlanCalculator.java:152)
        at org.apache.maven.lifecycle.internal.DefaultLifecycleExecutionPlanCalculator.setupMojoExecutions(DefaultLifecycleExecutionPlanCalculator.java:139)
        at org.apache.maven.lifecycle.internal.DefaultLifecycleExecutionPlanCalculator.calculateExecutionPlan(DefaultLifecycleExecutionPlanCalculator.java:116)
        at org.apache.maven.lifecycle.internal.DefaultLifecycleExecutionPlanCalculator.calculateExecutionPlan(DefaultLifecycleExecutionPlanCalculator.java:129)
        at org.apache.maven.lifecycle.internal.BuilderCommon.resolveBuildPlan(BuilderCommon.java:92)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
        at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
        at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
        at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
        at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:622)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
        at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
        at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
    Caused by: org.sonatype.aether.resolution.ArtifactDescriptorException: Failed to read artifact descriptor for org.apache.maven.plugins:maven-resources-plugin:jar:2.6
        at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.loadPom(DefaultArtifactDescriptorReader.java:296)
        at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.readArtifactDescriptor(DefaultArtifactDescriptorReader.java:186)
        at org.sonatype.aether.impl.internal.DefaultRepositorySystem.readArtifactDescriptor(DefaultRepositorySystem.java:279)
        at org.apache.maven.plugin.internal.DefaultPluginDependenciesResolver.resolve(DefaultPluginDependenciesResolver.java:115)
        ... 25 more
    Caused by: org.sonatype.aether.resolution.ArtifactResolutionException: Could not transfer artifact org.apache.maven.plugins:maven-resources-plugin:pom:2.6 from/to central (<a href="http://repo.maven.apache.org/maven2" rel="nofollow">http://repo.maven.apache.org/maven2</a>): repo.maven.apache.org
        at org.sonatype.aether.impl.internal.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:538)
        at org.sonatype.aether.impl.internal.DefaultArtifactResolver.resolveArtifacts(DefaultArtifactResolver.java:216)
        at org.sonatype.aether.impl.internal.DefaultArtifactResolver.resolveArtifact(DefaultArtifactResolver.java:193)
        at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.loadPom(DefaultArtifactDescriptorReader.java:281)
        ... 28 more
    Caused by: org.sonatype.aether.transfer.ArtifactTransferException: Could not transfer artifact org.apache.maven.plugins:maven-resources-plugin:pom:2.6 from/to central (<a href="http://repo.maven.apache.org/maven2" rel="nofollow">http://repo.maven.apache.org/maven2</a>): repo.maven.apache.org
        at org.sonatype.aether.connector.wagon.WagonRepositoryConnector$4.wrap(WagonRepositoryConnector.java:951)
        at org.sonatype.aether.connector.wagon.WagonRepositoryConnector$4.wrap(WagonRepositoryConnector.java:939)
        at org.sonatype.aether.connector.wagon.WagonRepositoryConnector$GetTask.run(WagonRepositoryConnector.java:669)
        at org.sonatype.aether.util.concurrency.RunnableErrorForwarder$1.run(RunnableErrorForwarder.java:60)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1146)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:701)
    Caused by: org.apache.maven.wagon.TransferFailedException: repo.maven.apache.org
        at org.apache.maven.wagon.shared.http.AbstractHttpClientWagon.fillInputData(AbstractHttpClientWagon.java:567)
        at org.apache.maven.wagon.StreamWagon.getInputStream(StreamWagon.java:116)
        at org.apache.maven.wagon.StreamWagon.getIfNewer(StreamWagon.java:88)
        at org.apache.maven.wagon.StreamWagon.get(StreamWagon.java:61)
        at org.sonatype.aether.connector.wagon.WagonRepositoryConnector$GetTask.run(WagonRepositoryConnector.java:601)
        ... 4 more
    Caused by: java.net.UnknownHostException: repo.maven.apache.org
        at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:175)
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:385)
        at java.net.Socket.connect(Socket.java:546)
        at java.net.Socket.connect(Socket.java:495)
        at java.net.Socket.(Socket.java:392)
        at java.net.Socket.(Socket.java:266)
        at org.apache.commons.httpclient.protocol.DefaultProtocolSocketFactory.createSocket(DefaultProtocolSocketFactory.java:80)
        at org.apache.commons.httpclient.protocol.DefaultProtocolSocketFactory.createSocket(DefaultProtocolSocketFactory.java:122)
        at org.apache.commons.httpclient.HttpConnection.open(HttpConnection.java:707)
        at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager$HttpConnectionAdapter.open(MultiThreadedHttpConnectionManager.java:1361)
        at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(HttpMethodDirector.java:387)
        at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:171)
        at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:397)
        at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:323)
        at org.apache.maven.wagon.shared.http.AbstractHttpClientWagon.execute(AbstractHttpClientWagon.java:446)
        at org.apache.maven.wagon.shared.http.AbstractHttpClientWagon.fillInputData(AbstractHttpClientWagon.java:561)
        ... 8 more</p>
  </blockquote>
  
  <p>I do have an internet connection. and I am not behind a proxy. </p>