Use Your Computer as a Hotspot (Software Access Point) for Local Network

Requirement and Eligibility Check

You need a nl80211 compatible wireless device, which supports the AP operating mode. Check with the following:

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iw list |grep AP

You should see something like this:

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Device supports AP-side u-APSD.

* AP

* AP/VLAN

* AP: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0

* AP/VLAN: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0

* AP: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0

* AP/VLAN: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0

* wake up on EAP identity request

* AP/VLAN

* #{ managed } <= 1, #{ AP, P2P-client, P2P-GO } <= 1, #{ P2P-device } <= 1,

Driver supports full state transitions for AP/GO clients

Driver/device bandwidth changes during BSS lifetime (AP/GO mode)

To check whether you can use your wifi (instead of ethernet) as access point (a wireless repeater). I do use this feature so that I can use my VPN service from my laptop instead of setting up VPN on my phone to save my phone battery.

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iw list |grep -A 4 "interface\ combinations"

---------------------------------------------

valid interface combinations:

* #{ managed } <= 1, #{ AP, P2P-client, P2P-GO } <= 1, #{ P2P-device } <= 1,

total <= 3, #channels <= 2

HT Capability overrides:

* MCS: ff ff ff ff ff ff ff ff ff ff

The constraint #channels <= 1 means that your software AP must operate on the same channel as your Wi-Fi client connection;

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lspci -k | grep -A 3 -i "network"

--------------------------------

08:00.0 Network controller: Intel Corporation Wireless 8260 (rev 3a)

Subsystem: Intel Corporation Device 1010

Kernel driver in use: iwlwifi

Kernel modules: iwlwifi

Now get the interface details of your wireless driver by,

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modinfo <whatever-kernel-> | grep 'depend'

Install and Config Software Access Point with create_ap

You can install it manually,

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git clone https://github.com/oblique/create_ap

cd create_ap

make install

Or, install the distro package for Arch.

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pacman -S create_ap

Retrieve the interface info;

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ip link # to list info

Cross your finger, toes and heart, and let create_ap do the magic. Use your phone to log into your new wifi hotspot. If it does not work, dig through here for some clues.

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sudo create_ap <--hidden> wlan0 eth0 SSID Passphrase

Here is what I got. If you want to run it as a background service then add –daemon argument (see discussed here).

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Config dir: /tmp/create_ap.wlp8s0.conf.Pg172rWP

PID: 32479

Network Manager found, set ap1 as unmanaged device... DONE

wlp8s0 is already associated with channel 6 (2437 MHz), fallback to channel 6

Creating a virtual WiFi interface... ap1 created.

Sharing Internet using method: nat

hostapd command-line interface: hostapd_cli -p /tmp/create_ap.wlp8s0.conf.Pg172rWP/hostapd_ctrl

Configuration file: /tmp/create_ap.wlp8s0.conf.Pg172rWP/hostapd.conf

Using interface ap1 with hwaddr a4:34:d9:51:17:66 and ssid "ARCH"

ap1: interface state UNINITIALIZED->ENABLED

ap1: AP-ENABLED

Finishing up

Run it as a system service

Modifying conf file accordingly:

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sudo nano /etc/create_ap.conf

--------------------------------------

HANNEL=default

GATEWAY=10.0.0.1

WPA_VERSION=2

　 ETC_HOSTS=0

　　DHCP_DNS=gateway

　　NO_DNS=0

　 HIDDEN=0 #change to 1 if you do not want to broadcast your SSID

　　MAC_FILTER=0

　 MAC_FILTER_ACCEPT=/etc/hostapd/hostapd.accept

　ISOLATE_CLIENTS=0

　SHARE_METHOD=nat

　IEEE80211N=0

　IEEE80211AC=0

　HT_CAPAB=[HT40+]

　VHT_CAPAB=

　DRIVER=nl80211

　NO_VIRT=0

　COUNTRY=

　FREQ_BAND=2.4

　NEW_MACADDR=

　DAEMONIZE=0

　NO_HAVEGED=0

　WIFI_IFACE=wlp8s0

　INTERNET_IFACE=enp9s0

　SSID=SSID

　PASSPHRASE=Passphrase

　USE_PSK=0

Start service immediately:

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systemctl start create_ap

I want the hotspot to be on when the system start; however, create_ap has to wait until the system is up and running. If create_ap fires before a valid network is established, it will unmanage/disable the interface and results in failed network. You have to delete the line in NetworkManager.conf,

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sudo nano /etc/NetworkManager/NetworkManager.conf

-------------------------------------------------

[main]

plugins=keyfile

[keyfile]

unmanaged-devices=interface-name:ap1

and restart the NetworkManager.service to regain its functionality.

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sudo systemctl restart NetworkManager.service

Here is what I did to make it work.

First, enable NetworkManager-wait-online.service if not already.

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sudo systemctl status NetworkManager-wait-online.service

Next, I increase the network load time from 30s to 60s.

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sudo nano /usr/lib/systemd/system/network-online.target.wants/NetworkManager-wait-online.service

----------------------------------------

[Service]

Type=oneshot

ExecStart=/usr/bin/nm-online -s -q --timeout=60

RemainAfterExit=yes

...

Add hook to run create_ap service after a successful connection from NetworkManager.

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sudo nano /usr/lib/systemd/system/create_ap.service

---------------------------------------

[uit]

Description=Create AP Service

After=network-online.target

Requires=network-online.target

...

Start on boot,

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systemctl enable create_ap
sytemctl status create_ap

Run it on demand with a command

create a shell script

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nano ~/usr/bin/hotspot
-------------------------
#!/bin/bash
sudo create_ap <--hidden> <--daemon> wlp8s0 enp9s0 SSID Passphrase
make it executable and elevate it to a system command

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$ chmod a+x ./hotspot
# sudo ln -sfv `readline -f ./htospot` /bin/hotspot
start your hotspot at will

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hotspot
Reboot and enjoy your hotspot!

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