[ 
https://issues.apache.org/jira/browse/ZOOKEEPER-236?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15969347#comment-15969347
 ] 

ASF GitHub Bot commented on ZOOKEEPER-236:
------------------------------------------

Github user afine commented on a diff in the pull request:

    https://github.com/apache/zookeeper/pull/184#discussion_r111612166
  
    --- Diff: src/java/main/org/apache/zookeeper/common/ZKTrustManager.java ---
    @@ -0,0 +1,137 @@
    +/**
    + * Licensed to the Apache Software Foundation (ASF) under one
    + * or more contributor license agreements.  See the NOTICE file
    + * distributed with this work for additional information
    + * regarding copyright ownership.  The ASF licenses this file
    + * to you under the Apache License, Version 2.0 (the
    + * "License"); you may not use this file except in compliance
    + * with the License.  You may obtain a copy of the License at
    + *
    + *     http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +package org.apache.zookeeper.common;
    +
    +import org.apache.http.conn.ssl.DefaultHostnameVerifier;
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
    +
    +import javax.net.ssl.SSLEngine;
    +import javax.net.ssl.SSLException;
    +import javax.net.ssl.X509ExtendedTrustManager;
    +import java.net.InetAddress;
    +import java.net.Socket;
    +import java.net.UnknownHostException;
    +import java.security.cert.CertificateException;
    +import java.security.cert.X509Certificate;
    +
    +/**
    + * A custom TrustManager that supports hostname verification via 
org.apache.http.conn.ssl.DefaultHostnameVerifier.
    + *
    + * We attempt to perform verification using just the IP address first and 
if that fails will attempt to perform a
    + * reverse DNS lookup and verify using the hostname.
    + */
    +public class ZKTrustManager extends X509ExtendedTrustManager {
    +
    +    private static final Logger LOG = 
LoggerFactory.getLogger(ZKTrustManager.class);
    +
    +    private X509ExtendedTrustManager x509ExtendedTrustManager;
    +    private boolean hostnameVerificationEnabled;
    +    private boolean shouldVerifyClientHostname;
    +
    +    private DefaultHostnameVerifier hostnameVerifier;
    +
    +    /**
    +     * Instantiate a new ZKTrustManager.
    +     *
    +     * @param x509ExtendedTrustManager    The trustmanager to use for 
checkClientTrusted/checkServerTrusted logic
    +     * @param hostnameVerificationEnabled If true, this TrustManager 
should verify hostnames.
    +     * @param shouldVerifyClientHostname  If true, and 
hostnameVerificationEnabled is true, the hostname of a client
    +     *                                    connecting to this machine will 
be verified in addition to the servers that this
    +     *                                    instance connects to. If false, 
and hostnameVerificationEnabled is true, only
    +     *                                    the hostnames of servers that 
this instance connects to will be verified. If
    +     *                                    hostnameVerificationEnabled is 
false, this argument is ignored.
    +     */
    +    public ZKTrustManager(X509ExtendedTrustManager 
x509ExtendedTrustManager, boolean hostnameVerificationEnabled, boolean 
shouldVerifyClientHostname) {
    +        this.x509ExtendedTrustManager = x509ExtendedTrustManager;
    +        this.hostnameVerificationEnabled = hostnameVerificationEnabled;
    +        this.shouldVerifyClientHostname = shouldVerifyClientHostname;
    +
    +        hostnameVerifier = new DefaultHostnameVerifier();
    +    }
    +
    +    @Override
    +    public X509Certificate[] getAcceptedIssuers() {
    +        return x509ExtendedTrustManager.getAcceptedIssuers();
    +    }
    +
    +    @Override
    +    public void checkClientTrusted(X509Certificate[] chain, String 
authType, Socket socket) throws CertificateException {
    +        if (hostnameVerificationEnabled && shouldVerifyClientHostname) {
    +            performHostVerification(socket.getInetAddress(), chain[0]);
    +        }
    +        x509ExtendedTrustManager.checkClientTrusted(chain, authType, 
socket);
    +    }
    +
    +    @Override
    +    public void checkServerTrusted(X509Certificate[] chain, String 
authType, Socket socket) throws CertificateException {
    +        if (hostnameVerificationEnabled) {
    +            performHostVerification(socket.getInetAddress(), chain[0]);
    +        }
    +        x509ExtendedTrustManager.checkServerTrusted(chain, authType, 
socket);
    +    }
    +
    +    @Override
    +    public void checkClientTrusted(X509Certificate[] chain, String 
authType, SSLEngine engine) throws CertificateException {
    +        if (hostnameVerificationEnabled && shouldVerifyClientHostname) {
    +            try {
    +                
performHostVerification(InetAddress.getByName(engine.getPeerHost()), chain[0]);
    +            } catch (UnknownHostException e) {
    +                throw new CertificateException("failed to verify host", e);
    +            }
    +        }
    +        x509ExtendedTrustManager.checkServerTrusted(chain, authType, 
engine);
    +    }
    +
    +    @Override
    +    public void checkServerTrusted(X509Certificate[] chain, String 
authType, SSLEngine engine) throws CertificateException {
    +        if (hostnameVerificationEnabled) {
    +            try {
    +                
performHostVerification(InetAddress.getByName(engine.getPeerHost()), chain[0]);
    +            } catch (UnknownHostException e) {
    +                throw new CertificateException("failed to verify host", e);
    +            }
    +        }
    +        x509ExtendedTrustManager.checkServerTrusted(chain, authType, 
engine);
    +    }
    +
    +    @Override
    +    public void checkClientTrusted(X509Certificate[] chain, String 
authType) throws CertificateException {
    +        x509ExtendedTrustManager.checkClientTrusted(chain, authType);
    +    }
    +
    +    @Override
    +    public void checkServerTrusted(X509Certificate[] chain, String 
authType) throws CertificateException {
    +        x509ExtendedTrustManager.checkServerTrusted(chain, authType);
    +    }
    +
    +    private void performHostVerification(InetAddress inetAddress, 
X509Certificate certificate) throws CertificateException {
    +        try {
    +            hostnameVerifier.verify(inetAddress.getHostAddress(), 
certificate);
    --- End diff --
    
    So we have a few hostname checks that we could consider. Please let me know 
if I am missing any.
    
    1. Check that the address/hostname of the machine matches what is listed on 
the certificate
    2. Check that the address/hostname of the machine matches what is expected 
from zoo.cfg (this may also require reading the sid from the packet sent when a 
connection is established). 
    3. Check that the address/hostname listed on the certificate matches what 
is expected from zoo.cfg
    
    This patch only performs check 1. I think that check 3 is something 
@geek101 mentioned earlier and we agreed this can be moved to another patch as 
it is more complicated. 
    
    I think it is also possible to implement check 2. This can exist entirely 
outside of tls/ssl support and is something we should consider based on its own 
merits. 
    
    I think having checks 1 and 2 would be plenty secure and we would not need 
check 3.
    
    Let me know what you think @hanm. 
    



> SSL Support for Atomic Broadcast protocol
> -----------------------------------------
>
>                 Key: ZOOKEEPER-236
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-236
>             Project: ZooKeeper
>          Issue Type: New Feature
>          Components: quorum, server
>            Reporter: Benjamin Reed
>            Assignee: Abraham Fine
>            Priority: Minor
>
> We should have the ability to use SSL to authenticate and encrypt the traffic 
> between ZooKeeper servers. For the most part this is a very easy change. We 
> would probably only want to support this for TCP based leader elections.



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