JAVA: How to create http url connection selecting the ip address to use

Question

I have a pool of public ip addresses configured on my multiple NICs. In my JAVA project, which runs on a LINUX machine, I need to select a specific ip address from the pool and create an HttpURLConnecion using that ip. Further, I will cycle on the pool, using each time a different ip.

At the current stage, I was not able to find a solution using the java.net library. I have rather looked at the HttpClient from Apache. At the following link, http://hc.apache.org/httpcomponents-client-ga/tutorial/html/connmgmt.html, it is said that such library can support the functionality I was looking for. A discussion on this can be found at Define source ip address using Apache HttpClient. Actually, the posted thread seems not conclusive, as users' experiences are very contrasting on the described use of the library.

Therefore, I don't think that SO community really succeeded in solving this issue. It is a matter of fact that several replayed questions/answers on this topic can be found on SO, but none of them seems to give an exhaustive analysis of the problem.

Moreover, the problem is not faced with the use of java.net library (as in my project) at all.

At the moment, a possible option that I have is to invoke some LINUX system commands (from java) to switch the NIC to use for the current connection. However, I have not figure it out yet.

Therefore, I would appreciate if any users, who had POSITIVE experiences in solving this issue, can address me to a solution/idea/method.

Thanks in advance,

Marcello

UPDATE:

I've currently implemented this test code. It gives me correct status code (200). However, it needs to be tested with multiple ip addresses.

public class test {

    public static void main(String[] args) {

        final String authUser = "admin";
        final String authPassword = "password";
        Authenticator.setDefault(
           new Authenticator() {
              public PasswordAuthentication getPasswordAuthentication() {
                 return new PasswordAuthentication(
                       authUser, authPassword.toCharArray());
              }
           }
        );

        System.setProperty("http.proxyUser", authUser);
        System.setProperty("http.proxyPassword", authPassword);

        try {

            Properties systemProperties = System.getProperties();
            URL url = new URL("yourURL");
            systemProperties.setProperty("http.proxyHost","localhost");
            systemProperties.setProperty("http.proxyPort", "8080");                         

            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            int status = connection.getResponseCode();
            System.out.println(status);

        } catch (IOException e) {
            System.out.println("connection problems");
        }
    }

}

At this point, you should be able to configure the different TCP ports related to each NIC. Did anyone try something like this? I am looking forward to reading new ideas/comments.

UPDATE 2: To be precise, I've included authentication setup for those who needed it.

Answer 1

Why don't you just use org.apache.httpcomponents?

Here an example that works (using maven plugin org.apache.httpcomponents, version 4.3.1):

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetAddress;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public class HttpClientExample {

    public void gogo() throws ClientProtocolException, IOException {

        CloseableHttpClient httpclient = HttpClients.createDefault();

        // Local interface1:
        byte ip1[] = new byte[] { (byte)192, (byte)168, (byte)100, (byte)32 };
        // Local interface2:
        byte ip2[] = new byte[] { (byte)192, (byte)168, (byte)100, (byte)33 };


        RequestConfig requestConfig = RequestConfig.custom().setLocalAddress(InetAddress.getByAddress(ip1)).build();
        try {
            HttpGet httpget = new HttpGet("http://server.com");
            httpget.setConfig(requestConfig);
            System.out.println("executing request" + httpget.getRequestLine());
            StringBuilder response = httpclient.execute(httpget,handler);
            System.out.println(response.toString());

            requestConfig = RequestConfig.custom().setLocalAddress(InetAddress.getByAddress(ip2)).build();
            httpget = new HttpGet("http://server.com");
            httpget.setConfig(requestConfig);
            System.out.println("executing request" + httpget.getRequestLine());
            response = httpclient.execute(httpget,handler);
            System.out.println(response.toString());
        } finally {
            httpclient.close();
        }
    }

    private final ResponseHandler<StringBuilder> handler = new ResponseHandler<StringBuilder>() {
        @Override
        public StringBuilder handleResponse(final HttpResponse response)
                throws ClientProtocolException, IOException {
            return sortResponse(response);
        }
    };

    private StringBuilder sortResponse(final HttpResponse httpResponse) throws IOException {
        StringBuilder builder = null;

        if (httpResponse != null) {
            switch (httpResponse.getStatusLine().getStatusCode()) {
                case HttpStatus.SC_OK:
                    final HttpEntity entity = httpResponse.getEntity();
                    if (entity != null) {

                        final InputStreamReader instream = new InputStreamReader(entity.getContent());
                        try {
                            final BufferedReader reader = new BufferedReader(instream);
                            builder = new StringBuilder();
                            String currentLine = null;
                            currentLine = reader.readLine();
                            while (currentLine != null) {
                                builder.append(currentLine).append("\n");
                                currentLine = reader.readLine();
                            }
                        } finally {
                            instream.close();
                        }
                    }
                    break;
                default:
                    throw new IllegalArgumentException("Error.");
            }
        }
        return builder;
    }
}

Answer 2

java.net uses sun.net.www.protocol package to create HttpURLConnection.

sun.net.www.protocol.HttpURLConnection is implementation of java.net.HttpURLConnection interface.

Try extending sun.net.www.protocol.HttpURLConnection and other appropriate classes like NetworkClient and HttpClient and protocol handler classes from sun.www. packages.

Answer 3

Use linux command "ip addr" which gives ouput similar to:

[root@user ~]# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host
    valid_lft forever preferred_lft forever
2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:18:a5:97 brd ff:ff:ff:ff:ff:ff
    inet 100.10.52.15/24 brd 10.0.2.255 scope global eth1
    inet 100.10.52.16/24 brd 10.0.2.255 scope global secondary eth1
    inet6 fe80::a00:27ff:fe18:a597/64 scope link
       valid_lft forever preferred_lft forever
3: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:11:1f:0c brd ff:ff:ff:ff:ff:ff
    inet 158.17.47.19/24 brd 172.17.37.255 scope global eth2
    inet6 fe80::a00:27ff:fe11:1f0c/64 scope link
       valid_lft forever preferred_lft forever
4: eth3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:cf:96:2d brd ff:ff:ff:ff:ff:ff
    inet6 fe80::a00:27ff:fecf:962d/64 scope link
       valid_lft forever preferred_lft forever

1. By default linux uses first ip address as source ip adress on perticular adapter. For example, for above system configuration linux will use "100.10.52.15/24" as source ip adress.

2. You can write java program with "ProcessBuilder" to execute following commands change order of ip address. (commands: ip addr del 100.10.25.15/24 dev eth0

   ip addr add 100.10.25.15/24 dev eth0)

3. Delete all ip addresses on perticular adapter, store it in memory. Add it in order you want (IP address which should use as source ip should add first)

4. For example ip adress "100.10.52.16/24" should use as source ip adress then

   ip addr del 100.10.25.15/24 dev eth0
   ip addr del 100.10.25.16/24 dev eth0
   
   ip addr add 100.10.25.16/24 dev eth0
   ip addr add 100.10.25.15/24 dev eth0
   

Answer 4

Well i dont have that particular answer for the same but ya u can try this may be i am not sure that will work or not but try once.

URL url = new URL(yourUrlHere);
Proxy proxy = new Proxy(Proxy.Type.DIRECT, 
    new InetSocketAddress( 
        InetAddress.getByAddress(
            new byte[]{your, ip, interface, here}), yourTcpPortHere));
URLConnection conn = url.openConnection(proxy);