checkstyle does not take into account proxy settings from settings.xml

I have the same problem but with a slightly different stack trace, and using version 2.1 of the plugin.
I am using NTLM APS to connect to the proxy, under Windows XP SP2.

Here is the log, trying to use checkstyle in Tiles 2:

+ Error stacktraces are turned on.
[INFO] Scanning for projects...
[INFO] Searching repository for plugin with prefix: 'checkstyle'.
[INFO] ----------------------------------------------------------------------------
[INFO] Building Tiles - Core Library
[INFO] task-segment: [checkstyle:checkstyle]
[INFO] ----------------------------------------------------------------------------
[INFO] Setting property: classpath.resource.loader.class => 'org.codehaus.plexus.velocity.ContextClassLoaderResourceLoader'.
[INFO] Setting property: velocimacro.messages.on => 'false'.
[INFO] Setting property: resource.loader => 'classpath'.
[INFO] Setting property: resource.manager.logwhenfound => 'false'.
[INFO] **************************************************************
[INFO] Starting Jakarta Velocity v1.4
[INFO] RuntimeInstance initializing.
[INFO] Default Properties File: org\apache\velocity\runtime\defaults\velocity.properties
[INFO] Default ResourceManager initializing. (class org.apache.velocity.runtime.resource.ResourceManagerImpl)
[INFO] Resource Loader Instantiated: org.codehaus.plexus.velocity.ContextClassLoaderResourceLoader
[INFO] ClasspathResourceLoader : initialization starting.
[INFO] ClasspathResourceLoader : initialization complete.
[INFO] ResourceCache : initialized. (class org.apache.velocity.runtime.resource.ResourceCacheImpl)
[INFO] Default ResourceManager initialization complete.
[INFO] Loaded System Directive: org.apache.velocity.runtime.directive.Literal
[INFO] Loaded System Directive: org.apache.velocity.runtime.directive.Macro
[INFO] Loaded System Directive: org.apache.velocity.runtime.directive.Parse
[INFO] Loaded System Directive: org.apache.velocity.runtime.directive.Include
[INFO] Loaded System Directive: org.apache.velocity.runtime.directive.Foreach
[INFO] Created: 20 parsers.
[INFO] Velocimacro : initialization starting.
[INFO] Velocimacro : adding VMs from VM library template : VM_global_library.vm
[ERROR] ResourceManager : unable to find resource 'VM_global_library.vm' in any resource loader.
[INFO] Velocimacro : error using VM library template VM_global_library.vm : org.apache.velocity.exception.ResourceNotFoundException: Unable to find resource 'VM_global_library.vm'
[INFO] Velocimacro : VM library template macro registration complete.
[INFO] Velocimacro : allowInline = true : VMs can be defined inline in templates
[INFO] Velocimacro : allowInlineToOverride = false : VMs defined inline may NOT replace previous VM definitions
[INFO] Velocimacro : allowInlineLocal = false : VMs defined inline will be global in scope if allowed.
[INFO] Velocimacro : initialization complete.
[INFO] Velocity successfully started.
[INFO] [checkstyle:checkstyle]
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] An error has occurred in Checkstyle report generation.

Embedded error: Unable to find configuration file location.
svn.apache.org
[INFO] ------------------------------------------------------------------------
[INFO] Trace
org.apache.maven.lifecycle.LifecycleExecutionException: An error has occurred in Checkstyle report generation.
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:559)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandaloneGoal(DefaultLifecycleExecutor.java:488)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:458)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:306)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:273)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:140)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:322)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:115)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:256)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Caused by: org.apache.maven.plugin.MojoExecutionException: An error has occurred in Checkstyle report generation.
at org.apache.maven.reporting.AbstractMavenReport.execute(AbstractMavenReport.java:79)
at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:412)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:534)
... 16 more
Caused by: org.apache.maven.reporting.MavenReportException: Unable to find configuration file location.
at org.apache.maven.plugin.checkstyle.CheckstyleReport.getConfigFile(CheckstyleReport.java:919)
at org.apache.maven.plugin.checkstyle.CheckstyleReport.executeReport(CheckstyleReport.java:466)
at org.apache.maven.reporting.AbstractMavenReport.generate(AbstractMavenReport.java:98)
at org.apache.maven.reporting.AbstractMavenReport.execute(AbstractMavenReport.java:73)
... 18 more
Caused by: java.net.UnknownHostException: svn.apache.org
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:177)
at java.net.Socket.connect(Socket.java:519)
at java.net.Socket.connect(Socket.java:469)
at sun.net.NetworkClient.doConnect(NetworkClient.java:157)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:388)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:500)
at sun.net.www.http.HttpClient.<init>(HttpClient.java:233)
at sun.net.www.http.HttpClient.New(HttpClient.java:306)
at sun.net.www.http.HttpClient.New(HttpClient.java:318)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:792)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:733)
at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:658)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:981)
at java.net.URL.openStream(URL.java:1009)
at org.codehaus.plexus.util.FileUtils.copyURLToFile(FileUtils.java:876)
at org.apache.maven.plugin.checkstyle.Locator.resolveLocation(Locator.java:100)
at org.apache.maven.plugin.checkstyle.CheckstyleReport.getConfigFile(CheckstyleReport.java:910)
... 21 more
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 19 seconds
[INFO] Finished at: Tue Feb 06 09:46:58 CET 2007
[INFO] Final Memory: 5M/9M
[INFO] ------------------------------------------------------------------------

My work around is to run with "-cpu -U" as this seems to force the checkstyle plugin to use the proxy specified in settings.xml.

It makes publishing a org.codehaus.mojo plugin project site from behind a proxy very difficult

The error persists with Maven 3.0.3 and maven-checkstyle-plugin 2.6. Please, assign the bug.

I created a simple patch that uses cargo's approach for applying the proxy settings. It's not beautiful but it works.