title: Nexus keeps saying "Remote automatically blocked and unavailable" for Eclipse P2 remote repository
body: <p>I added Eclipse P2 repository as proxies to my Nexus, but after checking the status for a while, the status turns to "Remote automatically blocked and unavailable". I configured for example the remote URL <a href="http://download.eclipse.org/eclipse/updates/4.4/" rel="noreferrer">http://download.eclipse.org/eclipse/updates/4.4/</a> with repository type P2. Is that correct and should it work like that? </p>
  
  <p>I thought I might have been blacklisted because of my many trials and errors, but when I use the same URL as repository in the POM, it works perfectly, even though its being fetched from the same IP. So there seems to be a problem with the Nexus proxy configuration. I configured the proxy like this:</p>
  
  <ul>
  <li>Repository type: Proxy</li>
  <li>Provider: P2 Update site</li>
  <li>Format: P2</li>
  <li>Policy: Mixed</li>
  <li>Remote storage location: <a href="http://download.eclipse.org/eclipse/updates/3.6/" rel="noreferrer">http://download.eclipse.org/eclipse/updates/3.6/</a></li>
  <li>Download remote indexes: false</li>
  <li>Auto blocking enabled: true</li>
  <li>File content validation: true</li>
  <li>Checksum policy: ignore</li>
  <li>Allow file browsing: true</li>
  <li>Include in search: false</li>
  <li>Publish URL: true</li>
  <li>Not found cache TTL: 1440 min</li>
  <li>Artifact max age: -1 min</li>
  <li>Metadata max age: 1440 min</li>
  <li>Item max age: 1440 min</li>
  <li>HTTP request settings: none configured</li>
  </ul>
  
  <p>Is the problem within this configuration?</p>
  
  <p>The log says just "timeout":</p>
  
  <pre>
  2015-05-25 19:40:51,544+0200 DEBUG [proxy-3-thread-389] smith remote.storage.outbound - [eclipse-3.6-try1] HEAD http://download.eclipse.org/eclipse/updates/3.6/ - 30,00 s
  2015-05-25 19:40:51,544+0200 DEBUG [proxy-3-thread-389] smith org.sonatype.nexus.proxy.storage.remote.httpclient.HttpClientRemoteStorage - HEAD method failed, will attempt GET. Exception: Connection pool timeout error while executing HEAD method [repositoryId="eclipse-3.6-try1", requestPath="/", remoteUrl="http://download.eclipse.org/eclipse/updates/3.6/"]
  org.sonatype.nexus.proxy.RemoteStorageTransportOverloadedException: Connection pool timeout error while executing HEAD method [repositoryId="eclipse-3.6-try1", requestPath="/", remoteUrl="http://download.eclipse.org/eclipse/updates/3.6/"]
      at org.sonatype.nexus.proxy.storage.remote.httpclient.HttpClientRemoteStorage.doExecuteRequest(HttpClientRemoteStorage.java:598) ~[nexus-core-2.11.2-03.jar:2.11.2-03]
      at org.sonatype.nexus.proxy.storage.remote.httpclient.HttpClientRemoteStorage.executeRequest(HttpClientRemoteStorage.java:515) ~[nexus-core-2.11.2-03.jar:2.11.2-03]
      at org.sonatype.nexus.proxy.storage.remote.httpclient.HttpClientRemoteStorage.executeRequestAndRelease(HttpClientRemoteStorage.java:622) ~[nexus-core-2.11.2-03.jar:2.11.2-03]
      at org.sonatype.nexus.proxy.storage.remote.httpclient.HttpClientRemoteStorage.checkRemoteAvailability(HttpClientRemoteStorage.java:371) ~[nexus-core-2.11.2-03.jar:2.11.2-03]
      at org.sonatype.nexus.proxy.storage.remote.AbstractHTTPRemoteRepositoryStorage.isReachable(AbstractHTTPRemoteRepositoryStorage.java:50) [nexus-core-2.11.2-03.jar:2.11.2-03]
      at org.sonatype.nexus.proxy.repository.AbstractProxyRepository.isRemoteStorageReachable(AbstractProxyRepository.java:1660) [nexus-core-2.11.2-03.jar:2.11.2-03]
      at org.sonatype.nexus.proxy.repository.AbstractProxyRepository$RemoteStatusUpdateCallable.call(AbstractProxyRepository.java:1634) [nexus-core-2.11.2-03.jar:2.11.2-03]
      at org.sonatype.nexus.threads.MDCAwareCallable.call(MDCAwareCallable.java:44) [nexus-core-2.11.2-03.jar:2.11.2-03]
      at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90) [shiro-core-1.2.3.jar:1.2.3]
      at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83) [shiro-core-1.2.3.jar:1.2.3]
      at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_31]
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_31]
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_31]
      at java.lang.Thread.run(Thread.java:745) [na:1.8.0_31]
  Caused by: org.apache.http.conn.ConnectionPoolTimeoutException: Timeout waiting for connection from pool
      at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.leaseConnection(PoolingHttpClientConnectionManager.java:254) ~[httpclient-4.3.6.jar:4.3.6]
      at org.apache.http.impl.conn.PoolingHttpClientConnectionManager$1.get(PoolingHttpClientConnectionManager.java:231) ~[httpclient-4.3.6.jar:4.3.6]
      at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:173) ~[httpclient-4.3.6.jar:4.3.6]
      at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:195) ~[httpclient-4.3.6.jar:4.3.6]
      at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:86) ~[httpclient-4.3.6.jar:4.3.6]
      at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:108) ~[httpclient-4.3.6.jar:4.3.6]
      at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184) ~[httpclient-4.3.6.jar:4.3.6]
      at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82) ~[httpclient-4.3.6.jar:4.3.6]
      at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:57) ~[httpclient-4.3.6.jar:4.3.6]
      at org.sonatype.nexus.proxy.storage.remote.httpclient.HttpClientRemoteStorage.doExecuteRequest(HttpClientRemoteStorage.java:557) ~[nexus-core-2.11.2-03.jar:2.11.2-03]
      ... 13 common frames omitted
  </pre>