Fresh install error

Greetings.

When trying to install v75 on fresh Ubuntu VPS, everything breaks suddenly in block

### Firewall

Various virtualized environments like Docker and some VPSs don't provide #NODOC

a kernel that supports iptables. To avoid error-like output in these cases, #NODOC

we skip this if the user sets DISABLE_FIREWALL=1. #NODOC

if [ -z "${DISABLE_FIREWALL:-}" ]; then # Install ufw which provides a simple firewall configuration. apt_install ufw

# Allow incoming connections to SSH.
ufw_limit ssh;

# ssh might be running on an alternate port. Use sshd -T to dump sshd's #NODOC
# settings, find the port it is supposedly running on, and open that port #NODOC
# too. #NODOC
SSH_PORT=$(sshd -T 2>/dev/null | grep "^port " | sed "s/port //" | tr '\n' ' ') #NODOC
if [ -n "$SSH_PORT" ]; then
    for port in $SSH_PORT; do
        if [ "$port" != "22" ]; then
            echo "Opening alternate SSH port $port." #NODOC
            ufw_limit "$port" #NODOC
        fi
    done
fi

ufw --force enable;

fi #NODOC

After commenting out this block, install process continues

If and when you have some time, try to figure out the problem, please.