Setup

This setup was done on an Intel Nuc.

The Nuc is running Ubuntu Server 18.04 Bionic, CLI only. It has a wired connection to a DHCP-enabled home router initially, but will use wireless internet after this in finished

Find and Start the Wireless Device

ip link

Mine was called wlp2s0. Start it:

ip link set dev wlp2s0 up

Download & Install wireless software

Ubuntu server doesn't ship with the required packages to connect to WiFi.

From another Ubuntu server that does have internet, plug in a USB stick and mount it. This example assumes it's mounted to /mnt.

I'm pretty sure that it can connect to WEP without this, and its just the newer WPA2 networks that basically everyone is using that need this.

# Delete anything currently in the apt cache
apt-get clean

# building some temp package lists, drop them in ~ or wherever
cd ~

# use apt-rdepends to get the dependencies
apt-get install apt-rdepends

# find deps for wireless-tools
apt-rdepends wireless-tools 2>/dev/null | grep "Depends: " | awk '{print $2}' | sort | uniq > packages1
echo wireless-tools >> packages1

# find deps for wpasupplicant
apt-rdepends wpasupplicant 2>/dev/null | grep "Depends: " | awk '{print $2}' | sort | uniq > packages2
echo wpasupplicant >> packages2
cat packages1 packages2 | sort | uniq > packages

# download the debs
cd /var/cache/apt/archives
cat ~/packages | while read p; do echo $p; apt-get download $p; done

# Copy the files
mkdir -p /mnt/debs
cp /var/cache/apt/archives/*.deb /mnt/debs
umount /mnt

Now remove the USB drive from that system and plug it into the offiline one.

# mount the usb drive
mount /dev/sdb1 /mnt

# move the files to your cache directory
cp /mnt/debs/* /var/cache/apt/archives/

# Install the packages
apt-get install wireless-tools wpasupplicant

Scan for SSIDs

The iwlist command can also give you other information about the network if you don't pipe its output to grep, but it's pretty verbose.

iwlist wlp2s0 scanning | grep -ie ssid

Join the WiFi Network with Netplan

You can use various commands to interactively connect to the network, but I want this connection to come up with the NUC. Netplan is the new tool used to configure networks since Ubuntu's Bionic stable release. Here's the netplan config I used. You can see the wired connection in there too, it doesn't need to be there once this is finished.

Be sure to replace "MySSID" and "My Password" with your own.

vi /etc/netplan/01-netcfg.yaml

network:
  version: 2
  renderer: networkd
  ethernets:
    enp0s25:
      dhcp4: yes
  wifis:
    wlp2s0:
      dhcp4: yes
      access-points:
        "MySSID":
          password: "My Password"

Then apply the changes.

netplan try

You should have an IP address now in ifconfig. For some reason I didn't get one right away, so I forced the DHCP request like this:

dhclient wlp2s0 -v

After that, you can connect to the wireless IP and don't need the wired one.

Reference Links

• AskUbuntu post about wpasupplicant
• Ubuntuforums.org netplan post