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I know how to create a hotspot when connected to a wired network, but when I am using internet from a WiFi connection, this disconnects the wireless connection the moment I activate the hotspot.

In Windows I can use Connectify Hotspot, which enables me to share the internet connection from the same wireless adapter as I am creating an access point on. As you can read on the technology overview page:

Access Point mode allows you to create a hotspot using the same Wi-Fi card that you are using to access the Internet.

How do I do this on Ubuntu?

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3  
Do you have two Wifi-Sticks or built-in-wifi? Because you need always one to receive and one to send. Even with connectify I think. If you look on their website they alsways show how to share 3G/4G via wifi, but never two wifi like they say in their advertisments. It IS possible, but only with two wifi adapters. I have never heard of a software technology that avoids that. There are other possibilities, though. –  verpfeilt Jul 11 '13 at 15:53
2  
I've voted to reopen this question, because it is different from the "How to Share your Internet Connection" question. First of all, the OP found that option already (so does not need the answers there) and secondly, it is about the situation to use a single networking device to share the connection from and to. See also Hotspot and Internet access together — why not? –  gertvdijk Jul 25 '13 at 18:07
    
Very Interesting. I like to add, that from the hardware site of things, you need a capable Wireless Card (I know that the lenovo in office is not able to create wireless AP's, it's simply not possible by hardware, business security means) Another thing, is, that you need at least two Antennas to really make it work, or a magic software that can emulate two connections on one Antenna. P.S.: I am not a hardware technician. It is possible that I understood nothing and talk rubbish. ;) –  mondjunge Jul 26 '13 at 8:59
    
@mondjunge The single antenna will only force you to use the same frequency/channel. But yes, of course this could be disabled in hardware completely. However, most chipsets are universal by hardware. It's just firmware + drivers that make the difference for most. –  gertvdijk Jul 26 '13 at 10:10

5 Answers 5

After I saw this link offered by vasishath, I managed to setup a wireless hotspot to share the internet connection from the same single wireless interface device. This wireless device must to use an Atheros driver that is already build with nl80211 support. Next I will show you how.

Detect if your wireless device will work with this method

Run the following command in terminal:

lsmod | grep ath

If the output is null or if the string cfg80211 is not in the output, it makes no sense to continue and you should pay attention at second and third point from this answer.

Tools needed

Check whether all the below mentioned packages are installed:

iw Install iw, hostapd Install hostapd, iptables Install iptables, udhcpd Install udhcpd, udhcpc Install udhcpc, macchanger Install macchanger.

Edit some files

Run the following command in terminal to edit corresponding files:

sudo -H gedit /etc/hostapd.conf /etc/udhcpd.conf /etc/wpa_supplicant.conf
  • In hostapd.conf file add the following code:

    interface=new1
    driver=nl80211
    ssid=my_wifi_hotspot      #Change the ssid name as you wish
    channel=11                #I sugest you to use the same channel as your wireless network
    hw_mode=g
    wme_enabled=1
    macaddr_acl=0
    auth_algs=1
    ignore_broadcast_ssid=0
    wpa=3
    wpa_passphrase=1234567890 #Change the passphrase as you wish
    wpa_key_mgmt=WPA-PSK
    wpa_pairwise=TKIP
    rsn_pairwise=CCMP
    
  • In udhcpd.conf file comment all the current lines (by adding a # character in front of the line) and add the following new lines:

    start 192.168.0.102         #These IPs must to be in the same subset as your current default route
    end 192.168.0.117 
    interface new1 
    
    opt dns 192.168.0.1         #Your current default route (Gateway)
    option subnet 255.255.255.0
    opt router 192.168.0.101    #This IP must to be in the same subset as your current default route
    option  domain  localhost
    
  • In wpa_supplicant.conf you must to provide the settings of your current wireless network. See man wpa_supplicant for some quick examples. And probably you have another examples in /usr/share/doc/wpa_supplicant/ directory. I used something like:

    ctrl_interface=/var/run/wpa_supplicant
    network={
      ssid="my_wifi_network"
      key_mgmt=WPA-PSK
      proto=WPA
      pairwise=CCMP
      group=CCMP
      psk="mypassphrase"
    }
    
  • Save all the files and close them.

Note: All of these edits doesn't affect with nothing your current network configuration.

Make a shell script

  • In a terminal run mkdir -p bin - this command will make a bin directory in your home folder if you don't already have it.
  • After run gedit ~/bin/hotspotsetup.sh - this will create the new file change_sources.sh in gedit.
  • Copy and paste the following script in the new created file:
#!/bin/bash

service network-manager stop
sleep 1

pkill -15 nm-applet
sleep 1

ifconfig wlan0 down             #wlan0 - the name of your wireless adapter
sleep 1

iw phy phy0 interface add new0 type station
iw phy phy0 interface add new1 type __ap
sleep 2

macchanger --mac 00:11:22:33:44:55 new0
macchanger --mac 00:11:22:33:44:66 new1
ifconfig new1 192.168.0.101 up  #192.168.0.101 - the same IP defined for router in 'udhcpd.conf' file 
hostapd /etc/hostapd.conf &
sleep 2

service udhcpd start

wpa_supplicant -inew0 -c/etc/wpa_supplicant.conf &
sleep 10

udhcpc -i new0

echo "1" > /proc/sys/net/ipv4/ip_forward
iptables --table nat --append POSTROUTING --out-interface new0 -j MASQUERADE
iptables --append FORWARD --in-interface new1 -j ACCEPT
  • Save the file and close it.
  • Go back into terminal and run: chmod +x ~/bin/hotspotsetup.sh - to grant execute access for the script.

Start the wireless hotspot being connected to a wireless network from the same wireless adapter

Run the above script in terminal with root privileges:

sudo ~/bin/hotspotsetup.sh

Proof

hotspotsetup.sh

Note: To start again your network-manager service as it was before to run the hotspotsetup.sh script, restart your computer (sudo reboot).

Source: Connectify for Linux with Single wireless interface.

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2  
It is out of the question if this is possible by hardware or not. If a Windows and FreeBSD application/driver can do this, then it should be possible in Ubuntu as well. Maybe not through the usual NetworkManager way, but that's not a criteria for a valid answer. –  gertvdijk Jul 26 '13 at 10:07
    
Windows and free version of Connectify definitely can use same wifi card for both receiving and sharing internet connection, I use this feature alot and its the only thing I miss from Windows. I'm sure this is doable in Ubuntu as well if somebody create an open source driver with same feature as Connectify. –  Nur Jul 28 '13 at 7:59
1  
@Nur There is a limited list of devices that have been tested by Connectify, or reported by multiple users, as fully-functional with Connectify Hotspot. So, not all devices will work in this sense –  Radu Rădeanu Jul 28 '13 at 12:27
    
I'm pretty sure my atheros card is fully functional because I already use connectify for ages, not a single problem happen. Gonna try this setup, I hope this'll work. –  Nur Jul 28 '13 at 17:44

As you can see in the comments to this answer ther IS a way of doing this. It's documented for FreeBSD (which is not Ubuntu/Linux) here: http://serverfault.com/questions/192144/connect-to-multiple-ap-with-one-wifi-adapter-under-linux-freebsd (Link from the comment). It does not seem to work exactly the same way on Linux, but it should be similar. Unfortunately I wasn't able to find more detailed information about this topic.

The probably easiest and most common way is using two physical network interfaces. So you may buy another wifi stick or just use another technology to connect further and do just one of them via Wifi. The possibilities are for example:

  • Bluetooth + Wifi
  • LAN/Ethernet + Wifi
  • 3G/LTE + Wifi
  • Wifi (external) + Wifi (built-in or second external)

Once I noticed that Ubuntu Linux is capable of managing two wifi devices at once without being complicated. I did not test this in ways of sharing the internet connection etc, but it should be possible. The way how complicated it will be is probably depending of the type of connections you use. On Linux you probably do not need and kind of special software. It should be possible to share connections without the need for any special tools. Unfortunately I cannot try it at this time.

I recommend you try Wifi to Wifi if you have another wifi stick anyway and otherwise LAN or Bluetooth (which is built-in in most notebooks). 3G/LTE sharing is a bit bad because of providers dataplans and so on.

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2  
    
Wow, it even does not seem to be that hard to do. At least on FreeBSD. But I still think, if this is supposed to be used often and/or many devices are supposed to be routed through these two connections, it's better to use two physical network interfaces if available. Also it should be relatively easy configurable with the ubuntu network settings (gui). It's a very interesting idea, though. Surely useful in some cases. I noticed some things in my answer that are misunderstandable (and some as you noticed, wrong). I'll edit it. –  verpfeilt Jul 25 '13 at 19:52

This was added as another answer because the other answer created so much controversy.

Most and foremost, you need to know the name of our wireless adapter. Use the below command to get it:

iwconfig

It would be most probably wlan0 or wlan1.

There are cases that we use old WiFi adapter and we want to know the driver it uses. We can use the below commands in accordance with it's type that is either USB or PCI.

lsusb
lspci

Use the below command to see which driver you currently use:

lsmod

Need to install a programs. Just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:

sudo apt-get install hostapd

Open the main network adapter configuration file by this command:

sudo gedit /etc/hostapd/hostapd.conf

And edit it like this:

interface=wlan0
driver=nl80211
country_code=US
ssid=mySSID
hw_mode=g
channel=1
wpa=2
wpa_passphrase=MyWiFiPassword
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP
auth_algs=1
macaddr_acl=0

The first line should be your network adapter name. The 2nd line should not be changed in most cases, unless you were not lucky and you require a 3rd party driver. The 3rd line does not require explanation. The 4th line should be your WiFi access point name (SSID). The fifth line identifies your network as a/b/g/n mode. The next line is your network channel. The remaining lines set security and encryption. In most cases, you only require to change pass phrase.

Open the 2nd configuration file by this command:

sudo gedit /etc/default/hostapd

And change it like this:

DAEMON_CONF="/etc/hostapd/hostapd.conf"
RUN_DAEMON="yes"
DAEMON_OPTS="-dd"

First line points to main network adapter configuration file. 2nd line tells hostapd to run in DAEMON mode in background on boot. The last line tells hostapd to log every message. The important trick here is if you like to use two different wireless network adapters to setup a Dual Band Access Point, you should create to separate original config files (1st file) for each ard and change it like this:

DAEMON_CONF="/etc/hostapd/hostapd.conf /etc/hostapd/hostapd2.conf"

The configurations are finished.

Running DAEMON

Now you have to ensure that hostapd DAEMON starts on boot (1st command below), you should also run it now to avoid a mandatory reboot.

sudo update-rc.d hostapd defaults
sudo /etc/init.d/hostapd start

And it is finished. Now we can connect to our newly built access point.

Sources:Hostapd:The Linux Way to create Virtual Wifi Access Point & Hostapd Linux documentation page

share|improve this answer
    
You said with your own words: "You need to know the name of the network adapter that you connect to the internet on. This must be different from the network adapter you configured above", but you specified the same: "ie wlan0". Also in the given source is specified very clear in the Concept section: "You need to have 2 interfaces, one which accesses the net (e.g. eth0), and other which provides the access point services (e.g. wlan0)". –  Radu Rădeanu Jul 28 '13 at 5:07
    
I think that the OP wants to use the same adapter: "But when I am browsing internet WiFi internet connection and I want to create a wireless hotspot the WiFi internet is disconnected". And gertvdijk specified this when he start the bounty. –  Radu Rădeanu Jul 28 '13 at 7:25
    
@RaduRădeanu Is this better? Will you let me know? Thanks –  Mitch Jul 28 '13 at 7:45
    
In my opinion the previous version was better (but is just an opinion). –  Radu Rădeanu Jul 28 '13 at 15:13

Its currently possible only for Atheros Cards and a very few Broadcom cards. To know which one you are using, please run the following command in terminal and paste the output here:-

lspci | Wireless

Or you can just straightforward try out that method. Here is the link for tutorial on how to do that:- connectify-for-linux-with-single-wireless-interface

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Please include the essential steps in the answer. Currently this is just a link-only answer which is frowned upon. It looks like a good source and instructions, so +1, but please improve your answer. –  gertvdijk Jul 27 '13 at 19:22

The best way I have found to create a CONNECTIFY EXPERIENCE is to use AP-HOTSPOT!
(WPA2..not wep like linux does by default in ubuntu)

sudo add-apt-repository ppa:nilarimogard/webupd8

sudo apt-get update

sudo apt-get install ap-hotspot

To Run and Options

Start: sudo ap-hotspot start

Stop: sudo ap-hotspot stop

Configure: sudo ap-hotspot Configure

Want a Graphical User Interface?

To install it open up a terminal, then browse to with:

cd /home/USERNAME/LOCATION

Then run the install commands:

qmake

make

Creates a program... Drag it to desktop and done :) cheers

As far as two adapters... Windows and free bsd can do it... As of now i'm still trying to figure it out as I only approached this scenario for myself as of yesterday! I will report back... Linux can do it as well.. It is not an hardware limitation for the adapters that can do it with other operating systems...

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Welcome to AskUbuntu. Henceforth please avoid using all capitals in your messages. It can be perceived as offending or aggressive. –  Luís de Sousa Feb 23 at 7:59

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