how to access my 127.0.0.1:8000 from android tablet

how to access my 127.0.0.1:8000 from android tablet - android

I am developing a webpage in django (on my pc with windows 7) and now i need to test some pages in tablet pcs. suddenly the thought came if i can have an access to my localhost in windows from android tablet. is that possible? I am in the same wifi connection in both devices at home.
i read a lot questions and answers regarding this issue in stackoverflow and other places, but none of them gave me some concrete solutions.
I have samsung tab 2 10.1 with android 4.0.4.
appreciate any help, thanks

So, there are a couple of issues it seems. The question most of the answers are addressing is "how do you connect to another server in your local network?" (or variants). There are two answers, you can use the computer's IP directly, or you can use the computer's name (you may need to append .local). For example, my computer is xavier.local.
The second issue is that you seem to be addressing is that runserver is not accessible via other computers on the network (this is your actual question). The reason is that by default Django's runserver will only acknowledge requests from the machine which is calling them. This means that the default settings would make it so that you would only be able to access the server from Windows (and they did this on purpose for security reasons). In order for it to listen to other requests you have two options:
runserver 192.168.1.101:8000
# Only handle requests which are made to the IP address 192.168.1.101
Or (and this is easier when dealing with more than one environment):
runserver 0.0.0.0:8000 # handle all requests
So, if your IP address is 192.168.1.101:
runserver # only requests made on the machine will be handled
runserver 127.0.0.1 # only requests made on the machine will be handled
runserver 192.168.1.101 # handles all requests (unless IP changes)
runserver 192.168.1.100 # does not handle any requests (wrong IP)
runserver 0.0.0.0 # handles all requests (even if the IP changes)
I do think it important to note that 0.0.0.0 is realistically not a security question when dealing with a local, development machine. It only becomes a significant problem when working on a large app with a machine which can be addressed from the outside world. Unless you have port forwarding (I do), or something wonky like that, you should not be too concerned.

Though this thread was active quite a long time ago. This is what worked for me on windows 10. Posting it in details. Might be helpful for the newbies like me.
Add ALLOWED_HOSTS = ['*'] in django settings.py file
run django server with python manage.py 0.0.0.0:YOUR_PORT. I used 9595 as my port.
Make firewall to allow access on that port:
Navigate to control panel -> system and Security -> Windows Defender Firewall
Open Advanced Settings, select Inbound Rules then right click on it and then select New Rule
Select Port, hit next, input the port you used (in my case 9595), hit next, select allow the connections
hit next again then give it a name and hit next for the last time.
Now find the ip address of your PC.
Open Command Promt as adminstrator and run ipconfig command.
You may find more than one ip addresses. As I'm connected through wifi I took the one under Wireless LAN adapter WiFi. In my case it was 192.168.0.100
Note that this ip may change when you reconnect to the network. So you need to check it again then.
Now from another device (pc, mobile, tablet etc.) connected to the same network go to ip_address:YOUR_PORT (in my case 192.168.0.100:9595)
Hopefully you'll be good to go !

You can find out what the ip address of your PC is with the ipconfig command in a Windows command prompt. Since you mentioned them being connected over WiFi look for the IP address of the wireless adapter.
Since the tablet is also in this same WiFi network, you can just type that address into your tablet's browser, with the :8000 appended to it and it should pull up the page.

127.0.0.1 is a loopback address that means, roughly, "this device"; your PC and your android tablet are separate devices, so each of them has its own 127.0.0.1. In other words, if you try to go to 127.0.0.1 on your Android tab, it's trying to connect to a webserver on the Android device, which is not what you want.
However, you should be able to connect over the wifi. On your windows box, open a command prompt and execute ipconfig. Somewhere in the output should be your windows box's address, probably 192.168.1.100 or something similar. You tablet should be able to see the Django server at that address.

need to know the ip address of your machine ..
Make sure both of your machines (tablet and computer) connected to same network
192.168.0.22 - say your machine address
do this :
192.168.0.22:8000 -- from your tablet
this is it !!!

If both are connected to the same network, all you need to do is provide the IP address of your server (in your network) in your Android app.

Tested using easy EasyPHP DevServer 14.1.
The trick is you must first add your local ip address to the Apache server to listen to it.
Right click on the tray icon, go to "Configuration" -> "Apache" in the "httpd.config"
# Change this to Listen on specific IP addresses as shown below to
# prevent Apache from glomming onto all bound IP addresses.
#
#Listen 12.34.56.78:80
Listen 127.0.0.1:80
Listen 192.168.0.201:80 <<-- ADD THIS LINE
Then go to your Control Panel and deactivate your Windows Firewall or add your Smartphone/Tablet Ip Address to the exception.
That's it. I hope it helps.
The IP Address 192.168.0.201 may be different from yours. 192.168.0.X

I've struggled with this problem myself, and I couldn't figure out what it was, since it worked perfectly on my iPhone, I decided to look into the problem and find a quick solution.
My local machine is a Mac OSX 10.10+, one option would have been to start an Apache server, but that's super unhandy - changing the DocumentRoot every time you want to check something quickly on your Android device. Besides that, changing the DocumentRoot is a pain in the a** on Mac OSX 10.10.
If you want to use:
python -m SimpleHTTPServer
on your Android, do this:
sudo python -m SimpleHTTPServer [ANY PORT YOU WANT, BUT NOT 8000]
I hope this helps.
cheerz -Pit

Try this
python manage.py runserver
then connect both tablet and system to same wifi and browse in the address
eg: python manage.py runserver 192.168.0.100:8000
In tablet type that url in adress bar

In my case I was required to disconnect and reconnect to the same network (both phone and pc), after changing the firewall settings.

Related

Android App using sql server database on a local PC with valid IP? [duplicate]

I'm able to access my laptop web server using the Android emulator, I'm using 10.0.2.2:portno
works well.
But when I connect my real Android phone, the phone browser can't connect to the same web server on my laptop. The phone is connected to the laptop using a USB cable. If I run the
adb devices command, I can see my phone.
What am I missing?

USB doesn't provide network to mobile device.
If both your desktop and phone are connected to the same WiFi (or any other local network), then use your desktop IP address assigned by the router (not localhost and not 127.0.0.1).
To find out the IP address of your desktop:
type into the command line ipconfig (Windows) or ifconfig (Unix)
on Linux the one-liner ifconfig | grep "inet " | grep -v 127.0.0.1 will yield only the important stuff
there's a bunch of suggestions on how to have a similar output on Windows
there's going to be a bunch of IP's
try all of them (except the forementioned localhost and 127.0.0.1)
If your phone is connected to the mobile network, then things are going to be harder.
Either go hardcore:
first find out your router external IP address (https://www.google.de/search?q=myip)
then, on the router, forward some port to <your desktop IP>:<server port number>
finally use the external IP address and forwarded port
Otherwise use something like xip.io or ngrok.
NOTE: The ifconfig command has been deprecated and thus missing by default on Debian Linux, starting from Debian stretch. The new and recommended alternative for examining a network configuration on Debian Linux is ip command. For example to use ip command to display a network configuration run the following:
ip address
The above ip command can be abbreviated to:
ip a
If you still prefer to use ifconfig as part of your daily sys admin routine, you can easily install it as part of the net-tools package.
apt-get install net-tools
Reference is here

It is actually quite simple.
Turn on WiFi Hotspot of your Android phone/router and connect your
Laptop to your phone
Start your server at localhost (I am using WAMP server for Windows)
Now open the command prompt and enter
ipconfig
Once you've done that, you will see something like the following:
Wireless LAN adapter Wireless Network Connection:
Connection-specific DNS Suffix . :
Link-local IPv6 Address . . . . . : fe80::80bc:e378:19ab:e448%11
IPv4 Address. . . . . . . . . . . : 192.168.43.76
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.43.1
Copy the IPv4 Address (in this case, it is 192.168.43.76)
In your mobile browser, simply paste the IPv4 Address
Note: Please set your network as "Home Network". Setting the network as Home Network means that you are allowing your PC to share stuff with other devices on the same network.
If you are using Windows 10, this can be done with the following:
Open Settings
Go to Network & Internet
Select WiFi in the left menu
Tap on the name of the connected WiFi
Set the Network Profile of the network to be Private
If you are having an issue, it is most likely to do with Windows Firewall.
Open Control Panel
Go to Windows Defender Firewall
Tap on Allow an app or feature through Windows Defender Firewall
Check whether the app is enabled for Private networks (there should be a tick)
If it is not enabled, tap Change settings and tick the checkbox under Private for the app

With the simple solution (just access laptop_ip_addr:port from mobile device, when mobile and laptop are on the same WiFi), I get a ERR_CONNECTION_REFUSED error. That is, my MacBook seems to refuse the connection attempt from my mobile.
ADB Reverse Socket (Android only)
This solution works for me (tested with a MacBook):
Connect Android mobile device with USB cable to laptop
Enable USB Debugging on mobile device
On laptop, run adb reverse tcp:4000 tcp:4000
Use your custom port number instead of 4000
Now, on the mobile device, you can navigate to http://localhost:4000/, and it will actually connect to the laptop, not the mobile device
See instructions here.
The downside is that this works only with a single mobile device at a time. If you want access with another mobile device, you have to first disconnect the first one (disable USB Debugging), connect the new one (enable USB Debugging), and run adb reverse tcp:4000 tcp:4000 again.
EDIT: this solution has been reported to also work with Windows.
ngrok (works with all devices)
Another solution that should always work is ngrok (as mentioned in other answers). It works over the Internet, and not the local network.
It's extremely easy to use:
brew install ngrok
ngrok http 4000
This outputs, among some other information, a line like
Forwarding http://4cc5ac02.ngrok.io -> localhost:4000
Now, you can navigate to http://4cc5ac02.ngrok.io on any device that is connected to the Internet, and this URL redirects to localhost:4000 of your laptop.
Note that as long as the ngrok command is running (until you hit Ctrl-C), your project is publicly served. Everybody who has the URL can see it.

Mac OS X users
I achieved this by enabling remote management:
Ensure that your phone and laptop are connected to the same WiFi network
On Mac, go to System preferences/sharing
Enable remote management
You will see a message similar to this:
Other users can manage your computer using the address some.url.com
On your Android device, you should now be able to go to some.url.com, which delegates to localhost on your Mac. You can also use ifconfig to get the IP address of your Mac.
Portable solution with ngrok (any OS with Node.js)
If you don't mind exposing your project with a temporary domain you can use ngrok. Lets say I have an app that runs on localhost:9460 I can simply write
npm install ngrok -g
ngrok http 9460
This will give me:
Session Status online
Update update available (version 2.2.8, Ctrl-U to update)
Version 2.2.3
Region United States (us)
Web Interface http://127.0.0.1:4040
Forwarding http://f7c23d14.ngrok.io -> localhost:9460
Forwarding https://f7c23d14.ngrok.io -> localhost:9460
Connections ttl opn rt1 rt5 p50 p90
0 0 0.00 0.00 0.00 0.00
I can now reach https://f7c23d14.ngrok.io as a way to remotely view localhost. This is great to share design work or progress with clients.
Alternate solution with nginx proxy pass
If you are running something like this through nginx proxy_pass it will require a bit more tweaking - this is a hacky approach, but it works for me and I am open to suggestions on improving it:
Enable remote management (as mentioned above)
Temporarily set the server to listen on port 81 as opposed to 80
Type in the following command:
sudo nginx -s reload
Visit http://youripaddress:81
server {
listen 80;
listen 81; # <-------- add this to expose the app on a unique port
server_name ~^(local|local\.m).example.com$;
# ...
}
Reload and visit http://youripaddress:81

This solution is usable even when your mobile device and computer is connected through usb:
You need to use port forwarding in this case.
In the Google chrome inspect window (chrome://inspect) You can see the connected devices.
Click on the port fowading button, and set a random port say 3000 to the port which your laptop uses say 8080.
now use localhost:3000 from device to access the localhost:8080(or_whatever_ip:portno) in the laptop.
You can check it in the mobile browser. Try localhost:3000 in the mobile browser.
Make sure to check the "Enable port forwarding" checkbox in the "Port forwarding settings" window

I found a quick solution to this problem. Try this link. It should help you fix the problem.
I only changed one thing, where the tutorial states you change '127.0.0.1' to 'All', change it to the IP address your server is running on instead.
After that, you should be able to connect to your localhost.
Below is a (proofread) copy of the information from the linked page:
Step 1
Install the Wamp server (or any other you prefer).
This is one of the best servers I know to set up a local server. If you have installed Apache or any other server, ignore this step.
Download and install Wamp Server from here.
Step 2
Add a new rule for port 80 in Windows Firewall.
Open the Control Panel and select Windows Firewall.
Select Advanced settings from the left panel of the Windows Firewall setting page.
Select Inbound Rules from the left panel, then select New Rule.
Select Port and click Next.
Select the “Specific local ports” radio button and enter 80 as the port value.
Keep Allow the connection unchanged and move to the next step.
Keep Profile options unchanged and click Next.
Give some nice name to your new rule and click Finish.
This will enable port 80 access on local network IP.
Step 3
Edit the httpd.conf file of the Wamp server to fix the 403 error.
We need to edit this file. Otherwise, we will get the 403 forbidden error when we access the localhost through a local network IP.
Click on the Wamp server tray icon.
Open Apache server sub menu.
Select httpd.conf.
Find this section of configuration in the httpd.conf file:
Directory “c:/wamp/www/”
#
# Possible values for the Options directive are “None”, “All”,
# or any combination of:
# Indexes Includes FollowSymLinks SymLinksifOwnerMatch ExecCGI MultiViews
#
# Note that “MultiViews” must be named *explicitly* — “Options All”
# doesn’t give it to you.
#
# The Options directive is both complicated and important. Please see
# http://httpd.apache.org/docs/2.2/mod/core.html#options
# for more information.
#
Options Indexes FollowSymLinks
#
# AllowOverride controls what directives may be placed in .htaccess files.
# It can be “All”, “None”, or any combination of the keywords:
# Options FileInfo AuthConfig Limit
#
AllowOverride all
#
# Controls who can get stuff from this server.
#
# onlineoffline tag – don’t remove
Order Deny,Allow
Deny from all
Allow from 127.0.0.1
Find and replace ‘127.0.0.1’ with ‘All’, save the file, and restart your Wamp server.
Step 4
Find your local network IP.
Open the command prompt.
Type and enter the ipconfig command.
In my case, my local area network address is 10.0.0.2.
This is the IP which you need to access your localhost on your Android phone over wifi. To test if it is working, type this IP address in your desktop browser where your localhost server is installed. The browser should display your localhost page successfully. This will assure that this local network IP is now successfully accessible on your Android phone.
I hope this tutorial will help you to access your localhost over wifi.

On Windows PC You may not need to do anything else than finding out your IPv4 Address using "ipconfig" command.
Step 1 : Connect your phone to PC using USB cable.
Step 2 : Use command 'ipconfig' to find out your IPv4 Address (External IP of the Router) e.g 192.168.1.5 in my case.
Step 3: Just access "192.168.1.5:8080" from your phone browser. It works !
Other Env Details :
Windows 7, Google Nexus 4 (4.2.2), Tomcat Server, Grails Application.
You should also make sure that you have the permission to access internet in AndroidManifest file :
<uses-permission android:name="android.permission.INTERNET"/>

There is however a far better solution. You can access your host machine with the IP address "10.0.2.2". This has been designed in this way by the Android team. So your webserver can perfectly run at localhost and from your Android app you can access it via "http://10.0.2.2:8080".

As this is an old question, there is a new way to do this that is really really simple. Download the ADB Chrome Extension and then follow these instructions:
https://developers.google.com/chrome-developer-tools/docs/remote-debugging

"Port forwarding on Chrome for Android makes it easy to test your development site on mobile. It works by creating a listening TCP port on your mobile device that maps to a particular TCP port on your development machine. Traffic between these ports travels through USB, so the connection doesn't depend on your network configuration."
More details here: https://developer.chrome.com/devtools/docs/remote-debugging#port-forwarding

Run CMD as administrator
and on CMD screen type ipconfig and the screen will appear with text
as this photo
and you can access your localhost using this ip
you have to be connected to same network as your pc connected to

Solution for Windows:
You are not able to view your website, mainly because your firewall (
default OS firewall or Antivirus firewall ) is preventing incoming
connections.
On Windows Firewall:
To allow incoming connections on specific ports, go to:
Control Panel > Windows Defender Firewall > Advanced Settings > Right
Click Inbound Rules > Add New Rule.
Then :
Select "Port" radio button.
Enter the specific port / range you on which you want to enable incoming connections ( the port on which your server is running )
Select "Allow the connection" radio button.
Click Next ( unless you want to change the defaults )
Give your rule a name and click Finish.
Note:
If you are using an Antivirus having a firewall, then the above steps will not work since the Antivirus would have disabled Windows firewall and instead runs its own firewall.
In that case, depending on the Antivirus program, go to your Antivirus's Firewall settings and open the port.

You may have your web server listening on your loopback interface and not on your network interface. Major signs of this are:
Hits on 127.0.0.1 and localhost (from localhost or Android emulator) work
Hits on 192.168.xxx.xxx do not work, whether from localhost, LAN, or WAN
I talk more about diagnosing this and fixing this in an answer here.

Try going to this file:
C:\wamp\bin\apache\Apache2.2.11\conf\httpd.conf
# onlineoffline tag - don't remove
Order Deny,Allow
Allow from all // change it Deny
Allow from 127.0.0.1
And change 10.0.2.2 to your IP address.

finally done in Ubuntu , i am running nodejs server on localhost:8080
1) open terminal type ifconfig
you will get ip something like this : inet addr:192.168.43.17
2) now simply put url address like this :
"192.168.43.17:8080" (8080 port coming from localhost port number)
ex : "192.168.43.17:8080/fetch"

Use this in your ubuntu/Macbook to get the ip address of your system. Your mobile and system should be in the same network
ip addr | grep inet This will give you an ip address which looks like 192.168.168.46. Use this in your smartphone.
Hope this helps.

If you are using a real device and still facing the problem, follow these steps as these steps help me to solve the issue:
Make sure both the mobile device and the laptop are on the same WiFi network.
verify your targeted URL has a port number, something like this:https://localhost:44301
run this command on the Android Studio terminal, adb reverse tcp:44301 tcp:44301
replace 44301 with your port number
Hopefully, you will be able to run without any issue.
Happy codding

I used this process:
Install Fiddler on the PC
Set up PC and Android device following these excellent instructions
Simply go to the browser on the Android device and type in http://ipv4.fiddler to access the localhost
Note that this process requires you to change the WiFi settings on the Android device at the start and end of every session. I found this less painful then rooting my Android device.

ngrok lets you put your localhost onto a temporary server and is very simple to set up. I've provided some steps here that can be found in the link:
Download the ngrok zip from the link above
Open the zip
Run your server locally and take note of the port number
In the terminal, go to the folder where ngrok lives and type ngrok http [port number]
You'll see a little dashboard in your terminal with an address pointing to your localhost. Point your app to that address and build to your device.

The easier way to default localhost is to use http://localhost:port. This works in a laptop and Android as well.
If it does not work, then in android set the default IP of your phone to 127.0.0.1:port :)
Open terminal and type :-
hostname -i
#127.0.0.1
hostname -I
#198.168.*.*

A solution to connect my mobile device to my wamp server based on my laptop:
First, wifi is not a router. So to connect my mobile device to my wamp server based on localhost on my laptop, I need a router.
I have downloaded and installed a free virtual router: https://virtualrouter.codeplex.com/
Configuring it is really simple:
right click on virtual router icon in System Tray
click on Configure virtual router
fill a password
if your internet connection is in ethernet, choose Shared connection : Ethernet
Then set wifi on on your laptop and device
On your device connect to the virtual router network name
Then you can connect to your laptop via your device by launching a browser and fill the IPV4 address of your laptop
(to find it on windows, type in cmd : ipconfig, and find ipv4 address)
You should see your wamp server home page.

Was running into this problem using several different localhost servers. Finally got my app up and running on the phone in seconds just by using the Python simple server. It only takes a few seconds so is worth a try before getting into any more complicated solutions. First, make sure you have Python installed. cmd+r and type python for Windows or $ python --version in mac terminal.
Next:
cd <your project root>
$ python -m SimpleHTTPServer 8000
Then just find the address of your host machine on the network, I used System Preferences/Sharing on mac to find it. Tap that into your Android device and should load your index.html and you should be good.
If not then the problem is something else and you may want to look into some of the other suggested solutions. Good luck!
* EDIT *
Another quick solution to try if you're using Chrome is the Web Server for Chrome extension. I found it a quick and super easy way to get access to localhost on my phone. Just make sure to check Accessible to local network under the Options and it should work on your cell without any problem.

This is what worked for me, I added another line after the 127.0.0.1 ip to specify the exact local network ip address (not the public ip address) of the device I wanted to use. In my case my Samsung Galaxy S3
As suggested by Bangptit edit the httpd.conf file (x being the version numbers):
C:\wamp\bin\apache\Apache2.x.x\conf\httpd.conf
Search for the onlineoffline tag and add the ip of your phone (I found my phones ip address in my routers configuration pages):
onlineoffline tag - don't remove
Order Deny,Allow
Deny from all
Allow from 127.0.0.1
my phones ip in the line below
Allow from 192.168.1.65
Allow from ::1
Allow from localhost
One could extend this to include an entire sub domain too for e.g. 192.168.1.0/24 etc

First of all connect your phone and computer to common wifi.
Then, open command prompt using run as administrator
Give ipconfig command
Which shows wireless lan ip
Use ip:port of your server to access in phone

EASIEST way (this worked flawlessly for me) is to locally host your site at 0.0.0.0:<port_no> and to access it using mobile devices, use <local_ipv4_address>:<port_no>/<path> in browser.
To know your local ipv4 address, just type ipconfig in cmd
ANY device connected to the SAME network can access this url.

Ngrok is the best solution.
If you're developing PHP then I recommend installing Laravel Valet, It has MacOS and Linux versions, then you may use valet share command. If you're developing any frontend tech and need to share a port like 3000 then use ngrok directly ngrok http 3000
Xampp & ngrok
You can also use ngrok with Xampp in Windows. You can use following process. It's quite easy and simple.
Sign up for a FREE account on ngrok
Download the ngrok file from Download section and Open it
Note the port your Apache server is running on. It's 80 in my case
In ngrok command line, enter ngrok http YOUR_PORT and copy the Forwarding address
Now you can use this Forwarding link on any device (i.e. your physical android devices) and it will be hosting your localhost server. For example,
Replace
http://localhost/my-files/
with
http://YOUR_FORWARDING_ADDRESS/my-files/

First of all make your machine(where server is running)IP address static. Enter this static IP address in the android code.
Next go to your wifi router's interface and check the left panel. You will see option such as port forwarding/forwarding. Click on it and forward port 80.
Now edit your htttpd.conf file and edit it for
Allow from All
. Restart your server. Everything should work fine now.
Additionally you can reserve the IP address of your machine so that it is always allocated to you.
In the left panel of your router's interface, find DHCP -> Address Reservation, click on it. Enter your machine's MAC address and the IP address you have entered in the code. Click on save. This will reserve the given IP address for your machine.

Adding a solution for future developers.
Copy address of your ip address. right click on your network -> network and sharing-> click on the connection you currently have-> details-> then the address beside ipv4 address is your ip address, note this down somewhere
Go to control panel -> system and security -> windows firewall -> advanced settings -> inbound rules -> new rules (follow the steps to add a port e.g 80, its really simple to follow)
put your ip address that you noted down on your phone browser and the port number you created the rule for beside it. e.g 192.168.0.2:80 and wala.
Possible solution if it doesn't connect.
right click network->open network and sharing-> look under view your active connections, under the name of your connection at the type of connection and click on it if it is public, and make sure to change it to a home network.

Although one answer has been accepted but this worked for me:
Make sure both your computer and android device are on same network.
get your computer's ip address. (in case of mac type ifconfig inside terminal and look for en0/en1 -> inet it should be something like 19*.16*.1.4.) (on windows, use `ipconfig)
Open your mobile settings and go to network-> long press your wifi network-> modify network -> scroll down to advanced options -> chose proxy manual and in proxy hostname type your address i.e. 19*.16*.1.4 inside port enter your port. and save it.
search for what is my ip in google chrome, and get your ip, lets say it is 1**.1**.15*.2**
try accessing 1**.1**.15*.2**:port/ from your mobile device.
It is as simple as this.

Building on Ilya Saunkin's answer, here's a command that should output your IP address formatted as a hyperlink - just substitute 3000 for whatever your port number is:
ifconfig | grep "inet " | grep -v 127.0.0.1 | sed 's/netmask.*//g' | sed 's/inet//g' | awk '{print "http://"$1":3000/"}'
Depending on where you're running the command, you should be able to (on a Mac) hold the command key and click/double-click to open the links.

receive data from localhost using retrofit in android enter onfailur case [duplicate]

I'm able to access my laptop web server using the Android emulator, I'm using 10.0.2.2:portno
works well.
But when I connect my real Android phone, the phone browser can't connect to the same web server on my laptop. The phone is connected to the laptop using a USB cable. If I run the
adb devices command, I can see my phone.
What am I missing?

USB doesn't provide network to mobile device.
If both your desktop and phone are connected to the same WiFi (or any other local network), then use your desktop IP address assigned by the router (not localhost and not 127.0.0.1).
To find out the IP address of your desktop:
type into the command line ipconfig (Windows) or ifconfig (Unix)
on Linux the one-liner ifconfig | grep "inet " | grep -v 127.0.0.1 will yield only the important stuff
there's a bunch of suggestions on how to have a similar output on Windows
there's going to be a bunch of IP's
try all of them (except the forementioned localhost and 127.0.0.1)
If your phone is connected to the mobile network, then things are going to be harder.
Either go hardcore:
first find out your router external IP address (https://www.google.de/search?q=myip)
then, on the router, forward some port to <your desktop IP>:<server port number>
finally use the external IP address and forwarded port
Otherwise use something like xip.io or ngrok.
NOTE: The ifconfig command has been deprecated and thus missing by default on Debian Linux, starting from Debian stretch. The new and recommended alternative for examining a network configuration on Debian Linux is ip command. For example to use ip command to display a network configuration run the following:
ip address
The above ip command can be abbreviated to:
ip a
If you still prefer to use ifconfig as part of your daily sys admin routine, you can easily install it as part of the net-tools package.
apt-get install net-tools
Reference is here

It is actually quite simple.
Turn on WiFi Hotspot of your Android phone/router and connect your
Laptop to your phone
Start your server at localhost (I am using WAMP server for Windows)
Now open the command prompt and enter
ipconfig
Once you've done that, you will see something like the following:
Wireless LAN adapter Wireless Network Connection:
Connection-specific DNS Suffix . :
Link-local IPv6 Address . . . . . : fe80::80bc:e378:19ab:e448%11
IPv4 Address. . . . . . . . . . . : 192.168.43.76
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.43.1
Copy the IPv4 Address (in this case, it is 192.168.43.76)
In your mobile browser, simply paste the IPv4 Address
Note: Please set your network as "Home Network". Setting the network as Home Network means that you are allowing your PC to share stuff with other devices on the same network.
If you are using Windows 10, this can be done with the following:
Open Settings
Go to Network & Internet
Select WiFi in the left menu
Tap on the name of the connected WiFi
Set the Network Profile of the network to be Private
If you are having an issue, it is most likely to do with Windows Firewall.
Open Control Panel
Go to Windows Defender Firewall
Tap on Allow an app or feature through Windows Defender Firewall
Check whether the app is enabled for Private networks (there should be a tick)
If it is not enabled, tap Change settings and tick the checkbox under Private for the app

Mac OS X users
I achieved this by enabling remote management:
Ensure that your phone and laptop are connected to the same WiFi network
On Mac, go to System preferences/sharing
Enable remote management
You will see a message similar to this:
Other users can manage your computer using the address some.url.com
On your Android device, you should now be able to go to some.url.com, which delegates to localhost on your Mac. You can also use ifconfig to get the IP address of your Mac.
Portable solution with ngrok (any OS with Node.js)
If you don't mind exposing your project with a temporary domain you can use ngrok. Lets say I have an app that runs on localhost:9460 I can simply write
npm install ngrok -g
ngrok http 9460
This will give me:
Session Status online
Update update available (version 2.2.8, Ctrl-U to update)
Version 2.2.3
Region United States (us)
Web Interface http://127.0.0.1:4040
Forwarding http://f7c23d14.ngrok.io -> localhost:9460
Forwarding https://f7c23d14.ngrok.io -> localhost:9460
Connections ttl opn rt1 rt5 p50 p90
0 0 0.00 0.00 0.00 0.00
I can now reach https://f7c23d14.ngrok.io as a way to remotely view localhost. This is great to share design work or progress with clients.
Alternate solution with nginx proxy pass
If you are running something like this through nginx proxy_pass it will require a bit more tweaking - this is a hacky approach, but it works for me and I am open to suggestions on improving it:
Enable remote management (as mentioned above)
Temporarily set the server to listen on port 81 as opposed to 80
Type in the following command:
sudo nginx -s reload
Visit http://youripaddress:81
server {
listen 80;
listen 81; # <-------- add this to expose the app on a unique port
server_name ~^(local|local\.m).example.com$;
# ...
}
Reload and visit http://youripaddress:81

This solution is usable even when your mobile device and computer is connected through usb:
You need to use port forwarding in this case.
In the Google chrome inspect window (chrome://inspect) You can see the connected devices.
Click on the port fowading button, and set a random port say 3000 to the port which your laptop uses say 8080.
now use localhost:3000 from device to access the localhost:8080(or_whatever_ip:portno) in the laptop.
You can check it in the mobile browser. Try localhost:3000 in the mobile browser.
Make sure to check the "Enable port forwarding" checkbox in the "Port forwarding settings" window

On Windows PC You may not need to do anything else than finding out your IPv4 Address using "ipconfig" command.
Step 1 : Connect your phone to PC using USB cable.
Step 2 : Use command 'ipconfig' to find out your IPv4 Address (External IP of the Router) e.g 192.168.1.5 in my case.
Step 3: Just access "192.168.1.5:8080" from your phone browser. It works !
Other Env Details :
Windows 7, Google Nexus 4 (4.2.2), Tomcat Server, Grails Application.
You should also make sure that you have the permission to access internet in AndroidManifest file :
<uses-permission android:name="android.permission.INTERNET"/>

There is however a far better solution. You can access your host machine with the IP address "10.0.2.2". This has been designed in this way by the Android team. So your webserver can perfectly run at localhost and from your Android app you can access it via "http://10.0.2.2:8080".

As this is an old question, there is a new way to do this that is really really simple. Download the ADB Chrome Extension and then follow these instructions:
https://developers.google.com/chrome-developer-tools/docs/remote-debugging

"Port forwarding on Chrome for Android makes it easy to test your development site on mobile. It works by creating a listening TCP port on your mobile device that maps to a particular TCP port on your development machine. Traffic between these ports travels through USB, so the connection doesn't depend on your network configuration."
More details here: https://developer.chrome.com/devtools/docs/remote-debugging#port-forwarding

Run CMD as administrator
and on CMD screen type ipconfig and the screen will appear with text
as this photo
and you can access your localhost using this ip
you have to be connected to same network as your pc connected to

Solution for Windows:
You are not able to view your website, mainly because your firewall (
default OS firewall or Antivirus firewall ) is preventing incoming
connections.
On Windows Firewall:
To allow incoming connections on specific ports, go to:
Control Panel > Windows Defender Firewall > Advanced Settings > Right
Click Inbound Rules > Add New Rule.
Then :
Select "Port" radio button.
Enter the specific port / range you on which you want to enable incoming connections ( the port on which your server is running )
Select "Allow the connection" radio button.
Click Next ( unless you want to change the defaults )
Give your rule a name and click Finish.
Note:
If you are using an Antivirus having a firewall, then the above steps will not work since the Antivirus would have disabled Windows firewall and instead runs its own firewall.
In that case, depending on the Antivirus program, go to your Antivirus's Firewall settings and open the port.

You may have your web server listening on your loopback interface and not on your network interface. Major signs of this are:
Hits on 127.0.0.1 and localhost (from localhost or Android emulator) work
Hits on 192.168.xxx.xxx do not work, whether from localhost, LAN, or WAN
I talk more about diagnosing this and fixing this in an answer here.

Try going to this file:
C:\wamp\bin\apache\Apache2.2.11\conf\httpd.conf
# onlineoffline tag - don't remove
Order Deny,Allow
Allow from all // change it Deny
Allow from 127.0.0.1
And change 10.0.2.2 to your IP address.

finally done in Ubuntu , i am running nodejs server on localhost:8080
1) open terminal type ifconfig
you will get ip something like this : inet addr:192.168.43.17
2) now simply put url address like this :
"192.168.43.17:8080" (8080 port coming from localhost port number)
ex : "192.168.43.17:8080/fetch"

Use this in your ubuntu/Macbook to get the ip address of your system. Your mobile and system should be in the same network
ip addr | grep inet This will give you an ip address which looks like 192.168.168.46. Use this in your smartphone.
Hope this helps.

If you are using a real device and still facing the problem, follow these steps as these steps help me to solve the issue:
Make sure both the mobile device and the laptop are on the same WiFi network.
verify your targeted URL has a port number, something like this:https://localhost:44301
run this command on the Android Studio terminal, adb reverse tcp:44301 tcp:44301
replace 44301 with your port number
Hopefully, you will be able to run without any issue.
Happy codding

I used this process:
Install Fiddler on the PC
Set up PC and Android device following these excellent instructions
Simply go to the browser on the Android device and type in http://ipv4.fiddler to access the localhost
Note that this process requires you to change the WiFi settings on the Android device at the start and end of every session. I found this less painful then rooting my Android device.

ngrok lets you put your localhost onto a temporary server and is very simple to set up. I've provided some steps here that can be found in the link:
Download the ngrok zip from the link above
Open the zip
Run your server locally and take note of the port number
In the terminal, go to the folder where ngrok lives and type ngrok http [port number]
You'll see a little dashboard in your terminal with an address pointing to your localhost. Point your app to that address and build to your device.

The easier way to default localhost is to use http://localhost:port. This works in a laptop and Android as well.
If it does not work, then in android set the default IP of your phone to 127.0.0.1:port :)
Open terminal and type :-
hostname -i
#127.0.0.1
hostname -I
#198.168.*.*

A solution to connect my mobile device to my wamp server based on my laptop:
First, wifi is not a router. So to connect my mobile device to my wamp server based on localhost on my laptop, I need a router.
I have downloaded and installed a free virtual router: https://virtualrouter.codeplex.com/
Configuring it is really simple:
right click on virtual router icon in System Tray
click on Configure virtual router
fill a password
if your internet connection is in ethernet, choose Shared connection : Ethernet
Then set wifi on on your laptop and device
On your device connect to the virtual router network name
Then you can connect to your laptop via your device by launching a browser and fill the IPV4 address of your laptop
(to find it on windows, type in cmd : ipconfig, and find ipv4 address)
You should see your wamp server home page.

Was running into this problem using several different localhost servers. Finally got my app up and running on the phone in seconds just by using the Python simple server. It only takes a few seconds so is worth a try before getting into any more complicated solutions. First, make sure you have Python installed. cmd+r and type python for Windows or $ python --version in mac terminal.
Next:
cd <your project root>
$ python -m SimpleHTTPServer 8000
Then just find the address of your host machine on the network, I used System Preferences/Sharing on mac to find it. Tap that into your Android device and should load your index.html and you should be good.
If not then the problem is something else and you may want to look into some of the other suggested solutions. Good luck!
* EDIT *
Another quick solution to try if you're using Chrome is the Web Server for Chrome extension. I found it a quick and super easy way to get access to localhost on my phone. Just make sure to check Accessible to local network under the Options and it should work on your cell without any problem.

This is what worked for me, I added another line after the 127.0.0.1 ip to specify the exact local network ip address (not the public ip address) of the device I wanted to use. In my case my Samsung Galaxy S3
As suggested by Bangptit edit the httpd.conf file (x being the version numbers):
C:\wamp\bin\apache\Apache2.x.x\conf\httpd.conf
Search for the onlineoffline tag and add the ip of your phone (I found my phones ip address in my routers configuration pages):
onlineoffline tag - don't remove
Order Deny,Allow
Deny from all
Allow from 127.0.0.1
my phones ip in the line below
Allow from 192.168.1.65
Allow from ::1
Allow from localhost
One could extend this to include an entire sub domain too for e.g. 192.168.1.0/24 etc

First of all connect your phone and computer to common wifi.
Then, open command prompt using run as administrator
Give ipconfig command
Which shows wireless lan ip
Use ip:port of your server to access in phone

EASIEST way (this worked flawlessly for me) is to locally host your site at 0.0.0.0:<port_no> and to access it using mobile devices, use <local_ipv4_address>:<port_no>/<path> in browser.
To know your local ipv4 address, just type ipconfig in cmd
ANY device connected to the SAME network can access this url.

Ngrok is the best solution.
If you're developing PHP then I recommend installing Laravel Valet, It has MacOS and Linux versions, then you may use valet share command. If you're developing any frontend tech and need to share a port like 3000 then use ngrok directly ngrok http 3000
Xampp & ngrok
You can also use ngrok with Xampp in Windows. You can use following process. It's quite easy and simple.
Sign up for a FREE account on ngrok
Download the ngrok file from Download section and Open it
Note the port your Apache server is running on. It's 80 in my case
In ngrok command line, enter ngrok http YOUR_PORT and copy the Forwarding address
Now you can use this Forwarding link on any device (i.e. your physical android devices) and it will be hosting your localhost server. For example,
Replace
http://localhost/my-files/
with
http://YOUR_FORWARDING_ADDRESS/my-files/

First of all make your machine(where server is running)IP address static. Enter this static IP address in the android code.
Next go to your wifi router's interface and check the left panel. You will see option such as port forwarding/forwarding. Click on it and forward port 80.
Now edit your htttpd.conf file and edit it for
Allow from All
. Restart your server. Everything should work fine now.
Additionally you can reserve the IP address of your machine so that it is always allocated to you.
In the left panel of your router's interface, find DHCP -> Address Reservation, click on it. Enter your machine's MAC address and the IP address you have entered in the code. Click on save. This will reserve the given IP address for your machine.

Adding a solution for future developers.
Copy address of your ip address. right click on your network -> network and sharing-> click on the connection you currently have-> details-> then the address beside ipv4 address is your ip address, note this down somewhere
Go to control panel -> system and security -> windows firewall -> advanced settings -> inbound rules -> new rules (follow the steps to add a port e.g 80, its really simple to follow)
put your ip address that you noted down on your phone browser and the port number you created the rule for beside it. e.g 192.168.0.2:80 and wala.
Possible solution if it doesn't connect.
right click network->open network and sharing-> look under view your active connections, under the name of your connection at the type of connection and click on it if it is public, and make sure to change it to a home network.

Although one answer has been accepted but this worked for me:
Make sure both your computer and android device are on same network.
get your computer's ip address. (in case of mac type ifconfig inside terminal and look for en0/en1 -> inet it should be something like 19*.16*.1.4.) (on windows, use `ipconfig)
Open your mobile settings and go to network-> long press your wifi network-> modify network -> scroll down to advanced options -> chose proxy manual and in proxy hostname type your address i.e. 19*.16*.1.4 inside port enter your port. and save it.
search for what is my ip in google chrome, and get your ip, lets say it is 1**.1**.15*.2**
try accessing 1**.1**.15*.2**:port/ from your mobile device.
It is as simple as this.

Building on Ilya Saunkin's answer, here's a command that should output your IP address formatted as a hyperlink - just substitute 3000 for whatever your port number is:
ifconfig | grep "inet " | grep -v 127.0.0.1 | sed 's/netmask.*//g' | sed 's/inet//g' | awk '{print "http://"$1":3000/"}'
Depending on where you're running the command, you should be able to (on a Mac) hold the command key and click/double-click to open the links.

Run ASP.NET application on server and access from remote computer/phone

I am trying to debug my visual studio 2012 asp.net project from my phone and have followed all steps here and here.
However none of them work, can't even connect from my other laptop. When I add my public IP or use * IISExpress doesnt even seem to pick up on it (Can't find it in IISExpress->show all applications). But When I used my local IP at least it showed up there and I could connect to it from my own computer, but no other computer/phone.
The cmd commands are successful, I add the extra binding, I open the firewall. Dont know what is wrong.
Which IP (local/public) should I use? what should I type in as URL when I want to test it? I am trying http://IP:port and http://IP:port/Default.aspx.
EDIT: Using this solution I got it to work on my laptop, however I still can not get it to work on my phone.

Basically, the points mentioned in the links you have cited are enough for enabling communication with the phone. But here is one point to make sure (since you have not mentioned it): You have to make sure that both the server and the clients (in your case, the machine that runs the visual studio and your phone and the other laptop) are on the same wireless network. To find out the IP that your server/development machine is currently using, you can issue ipconfig command in cmd and look at the Wireless Network Adapter IPV4 address. For example, if your laptop IP address is 192.168.1.2, you should use http://192.168.1.2:8080/Default.aspx (assuming that your site runs on the port 8080).

You use the local IP if you're on the same network as your server (for example, use WiFi on your phone and join the same network that your server is on).
You use the public IP if the device is outside your network, and you have to configure the firewall to forward the correct ports to the local IP. That's NAT traversal. This would be if you're using the phone's cellular data connection, or you're using a WiFi or wired network that's different from the one your server is on.
Your URL should always be of the format <protocol>://<IP or DNS name>:<port>/<path>. However, you can omit the IP (and the colon) if you're using HTTP on port 80, or HTTPS on port 443. And you can omit the path if you're accessing the root of the site, and your site has a page correctly configured for the root (either via default document in IIS, or route defaults if you're using routing features).

Localhost running on mac.. Can I view it on my Android phone?

Running a ruby on rails project on my mac. I need to test it on my android phone. Is there a way to view my mac localhost on my android phone?

The name "localhost" is just a loopback to your own computer. To access it on your Android, you need to find the computer's IP address.
The most general way of finding this info, which works on both Mac and Linux, is to go into the Terminal and type ifconfig. Look for either "en0" or "en1", and under that entry look for the "inet" listing. It will be something along the lines of "192.168.1.100". When you find that address, that's what you'll want to put in your browser's address bar.
(On a Mac specifically, you can go to the Sharing pane in System Preferences and it'll tell you there.)

Here's a quick to-do to have your localhost available for tests on other devices :
1) identify the IP of your Android : select the Wi-Fi you're connected (the same as the one the Mac is on), you'll have the IP detailed on it). For the example : we suppose your Android IP is : 192.168.0.10
2) open a Shell on your Mac and edit your host :
sudo nano /etc/hosts
3) edit the file as this :
127.0.0.1 192.168.0.10
4) Identify your Mac IP : (as #Chuck perfectly explained)
(in your shell) :
ifconfig
5) Open your favourite webbrowser you use on your phone and connect to your Mac IP (with the port if needed) with directly something like :
http://192.168.x.x:8000/
6) Enjoy your test :)
Notice you can do that for every support connected on your Wi-Fi.

Chunk's answer is correct, assuming your mobile device and your computer are on the same network. However, if you want your localhost server to be visible to the wider Internet (e.g. for testing over 3G, developing webhooks or collaboration with a remote colleague/client), more is needed as local addresses (starting with 10.* or 192.168.*) are not visible to the wider Internet.
The traditional solution to that is port forwarding and dynamic DNS, but lately a few services have popped up which aim to make this process simpler (disclaimer: I am the author of one of them, PageKite).
These services provide you with a public DNS name and software which connect your "localhost" with an in-the-cloud relay server (a.k.a. a reverse proxy). For example, if you are using PageKite, you can run the following command in the terminal:
$ pagekite.py 80 yourname.pagekite.me
... to create a mapping from http://yourname.pagekite.me/ to the web server running on http://localhost:80. While the program is running, your localhost site will be visible to the rest of the Internet. In order to make it private again, you simply turn off the pagekite.py connector program.
For completeness, here are some of the localhost tunneling services I am aware of:
PageKite is Free Software (Python) with a "pay-what-you-want" on-line service. You can create as many long-lived subdomains as you want, a wild-card SSL certificate is included and front-end relays run in multiple geographic locations to provide redundancy and responsiveness.
Localtunnel is a free-of-charge (sponsored by Twilio) Ruby solution which gives connections temporary names. Note that names are recycled so you may see unexpected traffic while the connection is live.
Showoff.io and Tunnlr.com are proprietary paid service comparable to Localtunnel, based on the same basic technology (ssh tunnels).
(Sorry about not linking to the last two, SO spam protection is preventing me from being fair to my competitors. ;-)

Found this great, free tool today - really easy to set up and works like a charm! Versions for Mac OS, Linux and Windows also available.
https://ngrok.com/
(am not associated with it in any way)

This worked for me for accessing rails server with IP over local network:
The firewall has to be turned off.
/etc/hosts should have this entry:
127.0.0.1 192.168.100.12
where 192.168.100.12 is the ip address which can be found by ifconfig command in terminal.
Start rails server with this command:
rails server -b 0.0.0.0 -p 8080
I was able to access my localhost through http://192.168.100.12:8080/

Additionally, if you want to test on Android/iOS device a PWA Apps developed with Angular, you will need to use:
ng serve --host 0.0.0.0 to start up the server CLI.
If you receive "Invalid Host Header", uses:
ng serve --host 0.0.0.0 --disableHostCheck true

after reading this thread (and the suggestions working!) I put together a single guide to solving this issue. This link to that guide that has screenshots for every step and where to look. Or the text is pasted below. Thank you for the help!
First off, both your phone and laptop must be connected to the same WiFi network. If you're using your phones mobile hotspot, it will still work. However, make sure to connect both devices to the same network before moving forward.
Next, collect your phones IP address. To do so, I use the Network Info II app. There is most definitely another way to accomplish this. However, Network Info II works as needed and is document for this tutorials sake.
Now open the terminal on your computer (don't worry about which directory you're within) and run the command sudo nano /etc/hosts/. After entering your system password, you'll see near the top of the terminal a string of numbers with the word localhost following. Localhost is in fact just an alias for your computer's own server address so that when you go to localhost in a browser it simply routes the http request to your local machine. In order to tie your phone into this loop, enter its IP address right between the string of numbers and Localhost.
To save this, hit control + X and then Y when prompted to save. After that, the enter key will bring you back to the standard command line.
Open a second tab in the terminal and launch a local server. I've only tested this using a simple python server, which can be run by running in the terminal python -m SimpleHTTPServer 8000. However, I'm assuming that you can launch any local server you like, being that all you'll need to reference is the port number. If you do use the simple python server, that port number is 8000.
Run ifconfig in the terminal. This will bring up a slew of information, to which you should scroll about halfway down. What you are looking for is a string of numbers that follow after an inet and before netmask within either the en0: or en1: key.
Done! On your Android, open up a browser and visit the inet number, followed by a colon (:) and the port number.

Although one answer has been accepted but this worked for me:
Make sure both your computer and android device are on same network.
get your computer's ip address. (in case of mac type ifconfig inside terminal and look for en0/en1 -> inet it should be something like 19*.16*.1.4.)
Open your mobile settings and go to network-> long press your wifi network-> modify network -> scroll down to advanced options -> chose proxy manual and in proxy hostname type your address i.e. 19*.16*.1.4 inside port enter your port. and save it.
search for what is my ip in google chrome, and get your ip, lets say it is 1**.1**.15*.2**
try accessing 1**.1**.15*.2**:port/ from your mobile device.
It is as simple as this.

MacOS Catalina 10.15.4
Go to Settings -> Security and Privacy.
Select Firewall tab and unlock the settings using your laptop password:
Select Firewall Options... and in the dialog uncheck the box for Block all incoming connections and hit OK.
Open Terminal and type ifconfig. Look for the en0. In the section find the address sitting near inet - this is the address of your laptop in a local network.
en0: flags0=<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 0
...
inet 192.168.0.123 netmask 0xffffff00 broadcast 192.168.0.255
...
Use the IP address + the port (in case you are using localhost:4200 for development), otherwise omit the port:
http://<IP address found in en0 -> inet>:<port if needed>
Profit!

If you run your localhost with php the solution was replacing localhost with the Macs IP
php -S 192.168.x.x:8080
instead of
php -S localhost:8080

For MacOs, open up System Preferences > Network.
you should see the message " and has the IP address: my-ip-address"
That will be your IP Address, then in the browser navigate to http://my-ip-address/port-number. Remember not to put an "s" in the http.

As mentioned in other answers, url has to consist of the IP address of computer and not localhost. If that isn't working, before trying anything else, check if the port is correctly mentioned along with IP address when making an api call in the Android app. That is, you should be making an api call to a url which is of the format: http://192.168.X.X:80/api/..

For using localhost on Android you should use your local ip address when connecting to it. First check your local ip address of your computer. Then follow along:
In addition to the good accepted answer, if you need to use localhost via your local ip address follow this steps:
Add your local ip address into httpd.conf (/etc/apache2/httpd.conf) as below:
(Change the port according to server you are using)
Listen 12.34.56.78:80
Listen: Allows you to bind Apache to specific IP addresses and/or ports, instead of the default.
Save, close and restart apache.

Access localhost wampserver via android device [duplicate]

I'm able to access my laptop web server using the Android emulator, I'm using 10.0.2.2:portno
works well.
But when I connect my real Android phone, the phone browser can't connect to the same web server on my laptop. The phone is connected to the laptop using a USB cable. If I run the
adb devices command, I can see my phone.
What am I missing?

USB doesn't provide network to mobile device.
If both your desktop and phone are connected to the same WiFi (or any other local network), then use your desktop IP address assigned by the router (not localhost and not 127.0.0.1).
To find out the IP address of your desktop:
type into the command line ipconfig (Windows) or ifconfig (Unix)
on Linux the one-liner ifconfig | grep "inet " | grep -v 127.0.0.1 will yield only the important stuff
there's a bunch of suggestions on how to have a similar output on Windows
there's going to be a bunch of IP's
try all of them (except the forementioned localhost and 127.0.0.1)
If your phone is connected to the mobile network, then things are going to be harder.
Either go hardcore:
first find out your router external IP address (https://www.google.de/search?q=myip)
then, on the router, forward some port to <your desktop IP>:<server port number>
finally use the external IP address and forwarded port
Otherwise use something like xip.io or ngrok.
NOTE: The ifconfig command has been deprecated and thus missing by default on Debian Linux, starting from Debian stretch. The new and recommended alternative for examining a network configuration on Debian Linux is ip command. For example to use ip command to display a network configuration run the following:
ip address
The above ip command can be abbreviated to:
ip a
If you still prefer to use ifconfig as part of your daily sys admin routine, you can easily install it as part of the net-tools package.
apt-get install net-tools
Reference is here

It is actually quite simple.
Turn on WiFi Hotspot of your Android phone/router and connect your
Laptop to your phone
Start your server at localhost (I am using WAMP server for Windows)
Now open the command prompt and enter
ipconfig
Once you've done that, you will see something like the following:
Wireless LAN adapter Wireless Network Connection:
Connection-specific DNS Suffix . :
Link-local IPv6 Address . . . . . : fe80::80bc:e378:19ab:e448%11
IPv4 Address. . . . . . . . . . . : 192.168.43.76
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.43.1
Copy the IPv4 Address (in this case, it is 192.168.43.76)
In your mobile browser, simply paste the IPv4 Address
Note: Please set your network as "Home Network". Setting the network as Home Network means that you are allowing your PC to share stuff with other devices on the same network.
If you are using Windows 10, this can be done with the following:
Open Settings
Go to Network & Internet
Select WiFi in the left menu
Tap on the name of the connected WiFi
Set the Network Profile of the network to be Private
If you are having an issue, it is most likely to do with Windows Firewall.
Open Control Panel
Go to Windows Defender Firewall
Tap on Allow an app or feature through Windows Defender Firewall
Check whether the app is enabled for Private networks (there should be a tick)
If it is not enabled, tap Change settings and tick the checkbox under Private for the app

Mac OS X users
I achieved this by enabling remote management:
Ensure that your phone and laptop are connected to the same WiFi network
On Mac, go to System preferences/sharing
Enable remote management
You will see a message similar to this:
Other users can manage your computer using the address some.url.com
On your Android device, you should now be able to go to some.url.com, which delegates to localhost on your Mac. You can also use ifconfig to get the IP address of your Mac.
Portable solution with ngrok (any OS with Node.js)
If you don't mind exposing your project with a temporary domain you can use ngrok. Lets say I have an app that runs on localhost:9460 I can simply write
npm install ngrok -g
ngrok http 9460
This will give me:
Session Status online
Update update available (version 2.2.8, Ctrl-U to update)
Version 2.2.3
Region United States (us)
Web Interface http://127.0.0.1:4040
Forwarding http://f7c23d14.ngrok.io -> localhost:9460
Forwarding https://f7c23d14.ngrok.io -> localhost:9460
Connections ttl opn rt1 rt5 p50 p90
0 0 0.00 0.00 0.00 0.00
I can now reach https://f7c23d14.ngrok.io as a way to remotely view localhost. This is great to share design work or progress with clients.
Alternate solution with nginx proxy pass
If you are running something like this through nginx proxy_pass it will require a bit more tweaking - this is a hacky approach, but it works for me and I am open to suggestions on improving it:
Enable remote management (as mentioned above)
Temporarily set the server to listen on port 81 as opposed to 80
Type in the following command:
sudo nginx -s reload
Visit http://youripaddress:81
server {
listen 80;
listen 81; # <-------- add this to expose the app on a unique port
server_name ~^(local|local\.m).example.com$;
# ...
}
Reload and visit http://youripaddress:81

This solution is usable even when your mobile device and computer is connected through usb:
You need to use port forwarding in this case.
In the Google chrome inspect window (chrome://inspect) You can see the connected devices.
Click on the port fowading button, and set a random port say 3000 to the port which your laptop uses say 8080.
now use localhost:3000 from device to access the localhost:8080(or_whatever_ip:portno) in the laptop.
You can check it in the mobile browser. Try localhost:3000 in the mobile browser.
Make sure to check the "Enable port forwarding" checkbox in the "Port forwarding settings" window

On Windows PC You may not need to do anything else than finding out your IPv4 Address using "ipconfig" command.
Step 1 : Connect your phone to PC using USB cable.
Step 2 : Use command 'ipconfig' to find out your IPv4 Address (External IP of the Router) e.g 192.168.1.5 in my case.
Step 3: Just access "192.168.1.5:8080" from your phone browser. It works !
Other Env Details :
Windows 7, Google Nexus 4 (4.2.2), Tomcat Server, Grails Application.
You should also make sure that you have the permission to access internet in AndroidManifest file :
<uses-permission android:name="android.permission.INTERNET"/>

There is however a far better solution. You can access your host machine with the IP address "10.0.2.2". This has been designed in this way by the Android team. So your webserver can perfectly run at localhost and from your Android app you can access it via "http://10.0.2.2:8080".

As this is an old question, there is a new way to do this that is really really simple. Download the ADB Chrome Extension and then follow these instructions:
https://developers.google.com/chrome-developer-tools/docs/remote-debugging

"Port forwarding on Chrome for Android makes it easy to test your development site on mobile. It works by creating a listening TCP port on your mobile device that maps to a particular TCP port on your development machine. Traffic between these ports travels through USB, so the connection doesn't depend on your network configuration."
More details here: https://developer.chrome.com/devtools/docs/remote-debugging#port-forwarding

Run CMD as administrator
and on CMD screen type ipconfig and the screen will appear with text
as this photo
and you can access your localhost using this ip
you have to be connected to same network as your pc connected to

Solution for Windows:
You are not able to view your website, mainly because your firewall (
default OS firewall or Antivirus firewall ) is preventing incoming
connections.
On Windows Firewall:
To allow incoming connections on specific ports, go to:
Control Panel > Windows Defender Firewall > Advanced Settings > Right
Click Inbound Rules > Add New Rule.
Then :
Select "Port" radio button.
Enter the specific port / range you on which you want to enable incoming connections ( the port on which your server is running )
Select "Allow the connection" radio button.
Click Next ( unless you want to change the defaults )
Give your rule a name and click Finish.
Note:
If you are using an Antivirus having a firewall, then the above steps will not work since the Antivirus would have disabled Windows firewall and instead runs its own firewall.
In that case, depending on the Antivirus program, go to your Antivirus's Firewall settings and open the port.

You may have your web server listening on your loopback interface and not on your network interface. Major signs of this are:
Hits on 127.0.0.1 and localhost (from localhost or Android emulator) work
Hits on 192.168.xxx.xxx do not work, whether from localhost, LAN, or WAN
I talk more about diagnosing this and fixing this in an answer here.

Try going to this file:
C:\wamp\bin\apache\Apache2.2.11\conf\httpd.conf
# onlineoffline tag - don't remove
Order Deny,Allow
Allow from all // change it Deny
Allow from 127.0.0.1
And change 10.0.2.2 to your IP address.

finally done in Ubuntu , i am running nodejs server on localhost:8080
1) open terminal type ifconfig
you will get ip something like this : inet addr:192.168.43.17
2) now simply put url address like this :
"192.168.43.17:8080" (8080 port coming from localhost port number)
ex : "192.168.43.17:8080/fetch"

Use this in your ubuntu/Macbook to get the ip address of your system. Your mobile and system should be in the same network
ip addr | grep inet This will give you an ip address which looks like 192.168.168.46. Use this in your smartphone.
Hope this helps.

If you are using a real device and still facing the problem, follow these steps as these steps help me to solve the issue:
Make sure both the mobile device and the laptop are on the same WiFi network.
verify your targeted URL has a port number, something like this:https://localhost:44301
run this command on the Android Studio terminal, adb reverse tcp:44301 tcp:44301
replace 44301 with your port number
Hopefully, you will be able to run without any issue.
Happy codding

I used this process:
Install Fiddler on the PC
Set up PC and Android device following these excellent instructions
Simply go to the browser on the Android device and type in http://ipv4.fiddler to access the localhost
Note that this process requires you to change the WiFi settings on the Android device at the start and end of every session. I found this less painful then rooting my Android device.

ngrok lets you put your localhost onto a temporary server and is very simple to set up. I've provided some steps here that can be found in the link:
Download the ngrok zip from the link above
Open the zip
Run your server locally and take note of the port number
In the terminal, go to the folder where ngrok lives and type ngrok http [port number]
You'll see a little dashboard in your terminal with an address pointing to your localhost. Point your app to that address and build to your device.

The easier way to default localhost is to use http://localhost:port. This works in a laptop and Android as well.
If it does not work, then in android set the default IP of your phone to 127.0.0.1:port :)
Open terminal and type :-
hostname -i
#127.0.0.1
hostname -I
#198.168.*.*

A solution to connect my mobile device to my wamp server based on my laptop:
First, wifi is not a router. So to connect my mobile device to my wamp server based on localhost on my laptop, I need a router.
I have downloaded and installed a free virtual router: https://virtualrouter.codeplex.com/
Configuring it is really simple:
right click on virtual router icon in System Tray
click on Configure virtual router
fill a password
if your internet connection is in ethernet, choose Shared connection : Ethernet
Then set wifi on on your laptop and device
On your device connect to the virtual router network name
Then you can connect to your laptop via your device by launching a browser and fill the IPV4 address of your laptop
(to find it on windows, type in cmd : ipconfig, and find ipv4 address)
You should see your wamp server home page.

Was running into this problem using several different localhost servers. Finally got my app up and running on the phone in seconds just by using the Python simple server. It only takes a few seconds so is worth a try before getting into any more complicated solutions. First, make sure you have Python installed. cmd+r and type python for Windows or $ python --version in mac terminal.
Next:
cd <your project root>
$ python -m SimpleHTTPServer 8000
Then just find the address of your host machine on the network, I used System Preferences/Sharing on mac to find it. Tap that into your Android device and should load your index.html and you should be good.
If not then the problem is something else and you may want to look into some of the other suggested solutions. Good luck!
* EDIT *
Another quick solution to try if you're using Chrome is the Web Server for Chrome extension. I found it a quick and super easy way to get access to localhost on my phone. Just make sure to check Accessible to local network under the Options and it should work on your cell without any problem.

This is what worked for me, I added another line after the 127.0.0.1 ip to specify the exact local network ip address (not the public ip address) of the device I wanted to use. In my case my Samsung Galaxy S3
As suggested by Bangptit edit the httpd.conf file (x being the version numbers):
C:\wamp\bin\apache\Apache2.x.x\conf\httpd.conf
Search for the onlineoffline tag and add the ip of your phone (I found my phones ip address in my routers configuration pages):
onlineoffline tag - don't remove
Order Deny,Allow
Deny from all
Allow from 127.0.0.1
my phones ip in the line below
Allow from 192.168.1.65
Allow from ::1
Allow from localhost
One could extend this to include an entire sub domain too for e.g. 192.168.1.0/24 etc

First of all connect your phone and computer to common wifi.
Then, open command prompt using run as administrator
Give ipconfig command
Which shows wireless lan ip
Use ip:port of your server to access in phone

EASIEST way (this worked flawlessly for me) is to locally host your site at 0.0.0.0:<port_no> and to access it using mobile devices, use <local_ipv4_address>:<port_no>/<path> in browser.
To know your local ipv4 address, just type ipconfig in cmd
ANY device connected to the SAME network can access this url.

Ngrok is the best solution.
If you're developing PHP then I recommend installing Laravel Valet, It has MacOS and Linux versions, then you may use valet share command. If you're developing any frontend tech and need to share a port like 3000 then use ngrok directly ngrok http 3000
Xampp & ngrok
You can also use ngrok with Xampp in Windows. You can use following process. It's quite easy and simple.
Sign up for a FREE account on ngrok
Download the ngrok file from Download section and Open it
Note the port your Apache server is running on. It's 80 in my case
In ngrok command line, enter ngrok http YOUR_PORT and copy the Forwarding address
Now you can use this Forwarding link on any device (i.e. your physical android devices) and it will be hosting your localhost server. For example,
Replace
http://localhost/my-files/
with
http://YOUR_FORWARDING_ADDRESS/my-files/

First of all make your machine(where server is running)IP address static. Enter this static IP address in the android code.
Next go to your wifi router's interface and check the left panel. You will see option such as port forwarding/forwarding. Click on it and forward port 80.
Now edit your htttpd.conf file and edit it for
Allow from All
. Restart your server. Everything should work fine now.
Additionally you can reserve the IP address of your machine so that it is always allocated to you.
In the left panel of your router's interface, find DHCP -> Address Reservation, click on it. Enter your machine's MAC address and the IP address you have entered in the code. Click on save. This will reserve the given IP address for your machine.

Adding a solution for future developers.
Copy address of your ip address. right click on your network -> network and sharing-> click on the connection you currently have-> details-> then the address beside ipv4 address is your ip address, note this down somewhere
Go to control panel -> system and security -> windows firewall -> advanced settings -> inbound rules -> new rules (follow the steps to add a port e.g 80, its really simple to follow)
put your ip address that you noted down on your phone browser and the port number you created the rule for beside it. e.g 192.168.0.2:80 and wala.
Possible solution if it doesn't connect.
right click network->open network and sharing-> look under view your active connections, under the name of your connection at the type of connection and click on it if it is public, and make sure to change it to a home network.

Although one answer has been accepted but this worked for me:
Make sure both your computer and android device are on same network.
get your computer's ip address. (in case of mac type ifconfig inside terminal and look for en0/en1 -> inet it should be something like 19*.16*.1.4.) (on windows, use `ipconfig)
Open your mobile settings and go to network-> long press your wifi network-> modify network -> scroll down to advanced options -> chose proxy manual and in proxy hostname type your address i.e. 19*.16*.1.4 inside port enter your port. and save it.
search for what is my ip in google chrome, and get your ip, lets say it is 1**.1**.15*.2**
try accessing 1**.1**.15*.2**:port/ from your mobile device.
It is as simple as this.

Building on Ilya Saunkin's answer, here's a command that should output your IP address formatted as a hyperlink - just substitute 3000 for whatever your port number is:
ifconfig | grep "inet " | grep -v 127.0.0.1 | sed 's/netmask.*//g' | sed 's/inet//g' | awk '{print "http://"$1":3000/"}'
Depending on where you're running the command, you should be able to (on a Mac) hold the command key and click/double-click to open the links.

Develop Reference

The Android operating system is a mobile operating system that was developed by Google (GOOGL?) to be primarily used for touchscreen devices, cell phones, and tablets.