Host-based Wi-Fi Access Point

Requirements

check for compatible drivers as defined at http://w1.fi/hostapd/

lsmod | grep mac80211

what Wi-Fi standards is the device able to talk? (we are gonna use G anyhow, not sure other standards are supported)

lshw -c network | egrep 'product|802.11'

Install

Debian / Ubuntu

apt install hostapd isc-dhcp-server

Slackware

slackpkg search hostapd dhcp

Setup

cp -pi /usr/share/doc/hostapd/examples/hostapd.conf /etc/hostapd/hostapd.conf.dist
grep -vE '^[[:space:]]*#|^[[:space:]]*$' /etc/hostapd/hostapd.conf.dist > /etc/hostapd/hostapd.conf.clean
grep -vE '^[[:space:]]*#|^[[:space:]]*$' /etc/hostapd/hostapd.conf.dist > /etc/hostapd/hostapd.conf
vi /etc/hostapd/hostapd.conf

...
ssid=as7lab
hw_mode=g
channel=11
...

wpa=2
wpa_key_mgmt=WPA-PSK
wpa_pairwise=CCMP
wpa_passphrase=12345678

#driver=nl80211

Ready to go

tail -n0 -F /var/log/*

Debian / Ubuntu

systemctl unmask hostapd
systemctl start hostapd
systemctl status hostapd

Slackware

/etc/rc.d/rc.hostapd stop
/etc/rc.d/rc.hostapd start

you can now set up the network for that purpose.

NAT

Set up an IP for that AP service

ifconfig wlan0 10.22.22.254/24 up

or at startup on Debian or Ubuntu w/o netplan

vi /etc/network/interfaces

auto wlan0
    iface wlan0 inet static
    address 10.22.22.254/24
    dns-search as7lab.lan
    dns-nameservers x.x.x.x x.x.x.x
    #dns-nameservers 208.67.222.222 208.67.220.220

enable forwarding and proceed

sysctl -w net.ipv4.ip_forward=1

with iptables

iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE

with nftables

table ip nat {
        chain postrouting {
                type nat hook postrouting priority srcnat;
                ip saddr 10.22.22.0/24 oif ppp0 masquerade
        }
}

DHCP

# slackware
mv -i /etc/dhcpd.conf /etc/dhcpd.conf.dist
vi /etc/dhcpd.conf

# debian/ubuntu
mv -i /etc/dhcp/dhcpd.conf /etc/dhcp/dhcpd.conf.dist
vi /etc/dhcp/dhcpd.conf

#option domain-name "as7lab.lan";
option domain-search "as7lab.lan";
option domain-name-servers x.x.x.x, x.x.x.x;
#option domain-name-servers 208.67.222.222, 208.67.220.220;

default-lease-time 600;
max-lease-time 7200;
ddns-update-style none;
authoritative;

subnet 10.22.22.0 netmask 255.255.255.0 {
        range 10.22.22.100 10.22.22.199;
        option subnet-mask 255.255.255.0;
        option routers 10.22.22.254;
}

Slackware

pkill dhcpd
dhcpd -q wlan0

Debian/Ubuntu

vi /etc/default/isc-dhcp-server

INTERFACESv4="wlan0"
INTERFACESv6=""

systemctl restart isc-dhcp-server
systemctl stop isc-dhcp-server6
systemctl disable isc-dhcp-server6