Programmatically getting the gateway and subnet mask details

Question

How can I get gateway and subnet mask details in Android?

Sincerity

Are u meaning you need to read the info of network parameters in WiFI? Or do you mean to read it for Mobile Network Connection like GPRS or EDGE?? – Laporte

@AndroidKid is there any way to read it for GPRS/EDGE/3G ? – Cerys

@Cerys There is way to see the cellular connection info using the test menu. Here are the steps Open dialer. Dial #*#4636#*# to open “Testing” screen. Tap on Phone Information. Scroll down ro see your IP, gateway and DNS details – Laporte

Answer 1

I have found a class called DhcpInfo within the android.net package. It has some public variables that stores the values of current Network parameters. But the problem is they return the value in integer converted from 8Bit shifted binary.

Sample Image Describing thee Scenario:

****Here is a sample code:**

**java file:****

package com.schogini.dhcp;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.widget.TextView;
import android.net.*;
import android.net.wifi.WifiManager;

public class dhcpInfo extends Activity {
    public String   s_dns1 ;
    public String   s_dns2;     
    public String   s_gateway;  
    public String   s_ipAddress;    
    public String   s_leaseDuration;    
    public String   s_netmask;  
    public String   s_serverAddress;
    TextView info;
    DhcpInfo d;
    WifiManager wifii;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        wifii= (WifiManager) getSystemService(Context.WIFI_SERVICE);
        d=wifii.getDhcpInfo();

        s_dns1="DNS 1: "+String.valueOf(d.dns1);
        s_dns2="DNS 2: "+String.valueOf(d.dns2);    
        s_gateway="Default Gateway: "+String.valueOf(d.gateway);    
        s_ipAddress="IP Address: "+String.valueOf(d.ipAddress); 
        s_leaseDuration="Lease Time: "+String.valueOf(d.leaseDuration);     
        s_netmask="Subnet Mask: "+String.valueOf(d.netmask);    
        s_serverAddress="Server IP: "+String.valueOf(d.serverAddress);

        //dispaly them
        info= (TextView) findViewById(R.id.infolbl);
        info.setText("Network Info\n"+s_dns1+"\n"+s_dns2+"\n"+s_gateway+"\n"+s_ipAddress+"\n"+s_leaseDuration+"\n"+s_netmask+"\n"+s_serverAddress);
    }
}

xml Coding:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.schogini.dhcp"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="4" />

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".dhcpInfo"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />  
</manifest>

I tried converting the integer value to its equivalent but i couldn't. If you do so you can post back.. Bye..

UPDATE: Some how managed to convert the IP to v4 Format from the integer form Conversion to IPv4 Format:

public String intToIp(int i) {

   return ((i >> 24 ) & 0xFF ) + "." +
               ((i >> 16 ) & 0xFF) + "." +
               ((i >> 8 ) & 0xFF) + "." +
               ( i & 0xFF) ;
}

IMAGE Courtesy: http://www.bennadel.com/blog/1830-Converting-IP-Addresses-To-And-From-Integer-Values-With-ColdFusion.htm

Laporte

Should you not use the >>> operator instead of >> – Crier

For some reason, the subnet mask seems to be the other way round, i.e. 0.255.255.255 instead of 255.255.255.0 in my case. – Precaution

@Precaution you can use Formatter.formatIpAddress(<yourIpAsInteger); – Tribble

Please note that the DhcpInfo class is deprecated as of API 18: developer.android.com/reference/android/net/DhcpInfo.html Already had some of my apps crash on me because of this. – Hygrophilous

@Hygrophilous And this class is marked as undepricated in API 19. – Trenatrenail

@Trenatrenail Well that seems odd.. (Not saying you're wrong of course). I should probably see if the issues I had with this on API18 are no longer there with API19. – Hygrophilous

Yes, that's strange. Goggle says that for API 18 it's deprecated. But for API 19 it's not deprecated anymore. – Trenatrenail

Internally in class DhcpInfo's private method putAddress the following code is used for the transformation from intAsIp to String: NetworkUtils.intToInetAddress(addr).getHostAddress(). But class NetworkUtils seems not to be part of the public API. – Lovesome

Why the ip address would be transferred into 0.0.255.255 – Uncurl

@Precaution Do you know why is that? The same error happens here. – Uncurl

Hey, Please try solution provided by @rtc11 – Laporte

@AndroidKid is right. now it works. i edited the post (waiting for approval) – Nimbus

+1 for the answer.Code is worked for me. But how to know ip is static or DHCP ? i changed DNS setting programatically and i want to restore the previous setting? how can we save current setting ? – Threaten

Its be a real crush on me that I couldnot figure out for ethernet as you did d=wifii.getDhcpInfo(); how can I get dhcp ifo for connected ethernet? – Condensate

netmask returns 0 always when on Lollipop.. any solution for this..? – Plough

@SagarD I had this problem. I used terminal command for get net mask. i run this code: process = Runtime.getRuntime().exec("ifconfig wlan0"); BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process.getInputStream())); then extract net mask from string. – Overhaul

I want to convert 24 to subnet mask address, which should be 255.255.255.0, but using the method you provided it converts 24 to 0.0.0.24 which is not expected. Also, JAVA only supports 'signed' integers, your example shows 'int', so how is integer representation of 255.255.255.0 would fit in signed-int ? – Cankered

Hi @Akoder, you found any way to do it ? – Decrescendo

Hi @Decrescendo – Cankered

Hi @Decrescendo I was able to do it, it's in two steps. First we should convert prefixLength to NetmaskInt. Let's say we have prefixLength = 24. 1) Use below method to get netmaskInt: int netmaskInt = Inet4AddressUtils.prefixLengthToV4NetmaskIntHTH(24); 2) Pass the netmaskInt to below method: public static String convertIntToIpString(int netmaskInt) { return ((netmaskInt >> 24) & 0xFF) + "." + ((netmaskInt >> 16) & 0xFF) + "." + ((netmaskInt >> 8) & 0xFF) + "." + (netmaskInt & 0xFF); } Thid should give you expected result : 255.255.255.0 – Cankered

Answer 2

Formatter.formatIpAddress(int) is deprecated, and we dont want to use deprecated methods do we?

AndroidKid's version of this is somehow reversed, but this should fix it:

public String intToIp(int addr) {
    return  ((addr & 0xFF) + "." + 
            ((addr >>>= 8) & 0xFF) + "." + 
            ((addr >>>= 8) & 0xFF) + "." + 
            ((addr >>>= 8) & 0xFF));
}

Source: http://www.devdaily.com/java/jwarehouse/android/core/java/android/net/DhcpInfo.java.shtml

Undersurface

Maybe it would be a bit more efficient to use StringBuffer instead of six string concatenations with operator "+" (for the latter on each concatenation the previous String-object is discarded and a new String-object is created), see this gist. – Lovesome

The compiler will actually create a stringbuffer and append the strings in this case. So it doesnt matter. If you however uses the method in iterations like: for(int i = 0; i<10; i++) intToIp(addr[i]); Then it will create six times ten strings. – Undersurface

Answer 3

to format the ip, try using:

import android.text.format.Formatter;

public String FormatIP(int IpAddress)
{
    return Formatter.formatIpAddress(IpAddress);
}

Pasteurizer

This method is deprecated... developer.android.com/reference/android/text/format/… – Laporte

It deprecated because of IPv6 but works for IPv4. You can choose another way especially for IPv6. – Tribble

Answer 4

This is an old Thread, but I found the official function used by android API (package android.net.NetworkUtils):

/**
 * Convert a IPv4 address from an integer to an InetAddress.
 * @param hostAddress an int corresponding to the IPv4 address in network byte order
 */
public static InetAddress intToInetAddress(int hostAddress) {
    byte[] addressBytes = { (byte)(0xff & hostAddress),
                            (byte)(0xff & (hostAddress >> 8)),
                            (byte)(0xff & (hostAddress >> 16)),
                            (byte)(0xff & (hostAddress >> 24)) };

    try {
       return InetAddress.getByAddress(addressBytes);
    } catch (UnknownHostException e) {
       throw new AssertionError();
    }
}

And once you have InetAddress you can get the formatted String this way:

intToInetAddress(d.gateway).getHostAddress()

Ephesian

Answer 5

Use Formatter.formatIpAddress(mask); mask is your int.

String maskk = Formatter.formatIpAddress(mask);

Willed

Answer 6

This version works with any Network (Wifi/Cell). Returns V4 and V6.

/**
 * Returns the set of all gateways<V4 & V6> for any Network
 *
 */
fun getGatewaySet(network:Network, context:Context):MutableSet<InetAddress> {
    val connectivityManager = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
    connectivityManager.getLinkProperties(network)?.routes?.let {
        //Saw dupes on my device, so use a set
        val set = mutableSetOf<InetAddress>()
        for (routeInfo in it) {
            routeInfo?.gateway?.let { inetAddress ->
                //If comes from AOSP isGateway() - requires API 29
                if (!inetAddress.isAnyLocalAddress) {
                    set.add(inetAddress)
                }
            }
        }
        return set
    }
    return Collections.EMPTY_SET as MutableSet<InetAddress>
}

Clone

Answer 7

Instead of getting 255.255.255.0, just change the order in return ;) So you will be able to get in the right order...

public String intToIp(int i) {

   return (i & 0xFF) + "." +
               ((i >> 8 ) & 0xFF) + "." +
               ((i >> 16 ) & 0xFF) + "." +
               ((i >> 24 ) & 0xFF) ;
}

Psychodynamics

Answer 8

Although old, works like a charm.

tvGateway.setText(Formatter.formatIpAddress(dhcpInfo.gateway));

Roseleeroselia