Free5GC: Install

A. Prerequisites
Linux Kernel Version

In order to use the UPF element, you must use the 5.0.0-23-generic or 5.4.x version of the Linux kernel. free5gc uses the gtp5g kernel module, which has been tested and compiled against that kernel versions only. If you installed 
Ubuntu 20.04, the version looks like 5.4.x. To determine the version of the Linux kernel you are using:
    $ uname -r
    5.4.0-65-generic
You will not be able to run most of the tests in Test section unless you deploy a UPF.

Golang Version

As noted above, free5gc is built and tested with Go 1.14.4
To check the version of Go on your system, from a command prompt:
    go version
If another version of Go is installed, remove the existing version and install Go 1.14.4:
    # this assumes your current version of Go is in the default location
    sudo rm -rf /usr/local/go
    wget https://dl.google.com/go/go1.14.4.linux-amd64.tar.gz
    sudo tar -C /usr/local -zxvf go1.14.4.linux-amd64.tar.gz
If Go is not installed on your system:
    wget https://dl.google.com/go/go1.14.4.linux-amd64.tar.gz
    sudo tar -C /usr/local -zxvf go1.14.4.linux-amd64.tar.gz
    mkdir -p ~/go/{bin,pkg,src}
    # The following assume that your shell is bash
    echo 'export GOPATH=$HOME/go' >> ~/.bashrc
    echo 'export GOROOT=/usr/local/go' >> ~/.bashrc
    echo 'export PATH=$PATH:$GOPATH/bin:$GOROOT/bin' >> ~/.bashrc
    echo 'export GO111MODULE=auto' >> ~/.bashrc
    source ~/.bashrc
Further information and installation instructions for golang are available at the official golang site.
Control-plane Supporting Packages

sudo apt -y update
sudo apt -y install mongodb wget git
sudo systemctl start mongodb
WARNING: MongoDB 5.0+ requires a CPU with AVX support. Or downgrade your MongoDB to 4.4

see https://www.mongodb.com/community/forums/t/mongodb-5-0-cpu-intel-g4650-compatibility/116610/2

see also docker-library/mongo#485 (comment)

User-plane Supporting Packages
sudo apt -y update
sudo apt -y install git gcc g++ cmake autoconf libtool pkg-config libmnl-dev libyaml-dev
Linux Host Network Settings
sudo sysctl -w net.ipv4.ip_forward=1
sudo iptables -t nat -A POSTROUTING -o <dn_interface> -j MASQUERADE
sudo iptables -A FORWARD -p tcp -m tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 1400
sudo systemctl stop ufw

B. Install Control Plane Elements
Clone the free5GC repository

To install the latest stable build (v3.2.1):
    cd ~
    git clone --recursive -b v3.2.1 -j `nproc` https://github.com/free5gc/free5gc.git
    cd free5gc
(Alternatively) to install the latest nightly build:
    cd ~/free5gc
    git checkout main
    git submodule sync
    git submodule update --init --jobs `nproc`
    git submodule foreach git checkout main
    git submodule foreach git pull --jobs `nproc`
Compile network function services in free5gc

To do so individually (e.g., AMF only):
    cd ~/free5gc
    make amf
To build all network functions:
    cd ~/free5gc
    make

C. Install User Plane Function (UPF)
As noted above, the GTP kernel module used by the UPF requires that you use Linux kernel version 5.0.0-23-generic or 5.4.x. To verify your version:
uname -r
Retrieve the 5G GTP-U kernel module using git and build it
git clone https://github.com/free5gc/gtp5g.git
cd gtp5g
make
sudo make install
Build the UPF (you may skip this step if you built all network functions above):

to build using make:
cd ~/free5gc
make upf
Customize the UPF as desired. The UPF configuration file in run.sh is free5gc/config/upfcfg.yaml.

D. Install WebConsole
Before building WebConsole, install nodejs and yarn packages first:
sudo apt remove cmdtest
sudo apt remove yarn
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
curl -sL https://deb.nodesource.com/setup_12.x | sudo -E bash -
sudo apt-get update
sudo apt-get install -y nodejs yarn
Build WebConsole

to build using make:
cd ~/free5gc
make webconsole
(Alternatively) to build manually:
cd ~/free5gc/webconsole/frontend
yarn install
yarn build
rm -rf ../public
cp -R build ../public
cd ..
go build -o bin/webconsole server.go
Note: 2GB or more of OS memory is recommended. WebConsole may be failed to build if memory is less then 1GB.