After going through the source code for firefox for andoroid which can be found at http://hg.mozilla.org/mozilla-central/ , these were the network related findings that I've made. The application uses maily 3 layers to work. 1) The core layer, written in C++. 2) A JS layer with some more functional code. 3) A Java layer that makes uses the Android API's and other code used for android. Out of the 3 layers, 2 of them make network calls. 1) The C++ layer. There is an advantage of this layer making the network calls as all the calls made by this layer are proxied. They obey the fennec settings for proxy that has currently been set at mozilla-central/mobile/android/app/mobile.js . Hence, we do not need to bother about setting proxy to these connections and calls. 2) The Java layer. The Java code, the code run by android also has many network calls but the problem is that these calls are not done obeying the tor proxy and hence they are harmful. List of places where these calls are made are: a) any class which imports org.apache.* (commons.net.ftp.*, http.*): build/mobile/sutagent/android/DoCommand.java build/mobile/sutagent/android/SUTAgentAndroid.java mobile/android/base/distribution/Distribution.java mobile/android/base/favicons/LoadFaviconTask.java mobile/android/base/tests/BaseRobocopTest.java b) The browser also seems to be using another library for network communications and that lies at mobile/android/thirdparty/ch/boye/httpclientandroidlib This library seems to have proxy support but the calls made to this library have not been proxied, a list of those are here: mobile/android/base/background/bagheera/BagheeraClient.java mobile/android/base/background/bagheera/BagheeraRequestDelegate.java mobile/android/base/background/bagheera/BoundedByteArrayEntity.java mobile/android/base/background/bagheera/DeflateHelper.java mobile/android/base/background/fxa/FxAccountClient10.java mobile/android/base/background/fxa/FxAccountClient20.java mobile/android/base/background/fxa/FxAccountClientException.java mobile/android/base/background/fxa/SkewHandler.java mobile/android/base/background/fxa/oauth/FxAccountAbstractClient.java mobile/android/base/background/fxa/oauth/FxAccountAbstractClientException.java mobile/android/base/background/fxa/oauth/FxAccountOAuthClient10.java mobile/android/base/background/healthreport/upload/AndroidSubmissionClient.java mobile/android/base/browserid/verifier/AbstractBrowserIDRemoteVerifierClient.java mobile/android/base/browserid/verifier/BrowserIDRemoteVerifierClient10.java mobile/android/base/sync/GlobalSession.java mobile/android/base/sync/jpake/JPakeClient.java mobile/android/base/sync/jpake/stage/DeleteChannel.java mobile/android/base/sync/jpake/stage/GetChannelStage.java mobile/android/base/sync/jpake/stage/GetRequestStage.java mobile/android/base/sync/jpake/stage/PutRequestStage.java mobile/android/base/sync/net/AbstractBearerTokenAuthHeaderProvider.java mobile/android/base/sync/net/AuthHeaderProvider.java mobile/android/base/sync/net/BaseResource.java mobile/android/base/sync/net/BaseResourceDelegate.java mobile/android/base/sync/net/BasicAuthHeaderProvider.java mobile/android/base/sync/net/HMACAuthHeaderProvider.java mobile/android/base/sync/net/HawkAuthHeaderProvider.java mobile/android/base/sync/net/HttpResponseObserver.java mobile/android/base/sync/net/MozResponse.java mobile/android/base/sync/net/Resource.java mobile/android/base/sync/net/ResourceDelegate.java mobile/android/base/sync/net/SyncResponse.java mobile/android/base/sync/net/SyncStorageCollectionRequest.java mobile/android/base/sync/net/SyncStorageRequest.java mobile/android/base/sync/net/SyncStorageResponse.java mobile/android/base/sync/net/TLSSocketFactory.java mobile/android/base/sync/repositories/Server11RepositorySession.java mobile/android/base/sync/setup/auth/AuthenticateAccountStage.java mobile/android/base/sync/setup/auth/EnsureUserExistenceStage.java mobile/android/base/sync/setup/auth/FetchUserNodeStage.java mobile/android/base/sync/stage/EnsureClusterURLStage.java mobile/android/base/sync/stage/SyncClientsEngineStage.java mobile/android/base/tokenserver/TokenServerClient.java mobile/android/tests/background/junit3/src/sync/TestUpgradeRequired.java This is the url for the query, https://dxr.mozilla.org/mozilla-central/search?q=ch.boye.httpclientandroidlib&case=false&offset=700 NOTE: Not all these classes make network calls, I will make a shorter list of this in the next few days.