Seal VPN Not Working in ubuntu 18+

Catalogue

Ubuntu18以上无法访问网络的解决办法
Ubuntu 18.04 以后，系统预设安装 systemd-resolved，劫持了 /etc/resolve.conf
用 symbolic link 指向 /run/systemd/resolve/stub-resolv.conf
NetworkManager 发现 /etc/resolv.conf 为 symbolic-link, 会忽略我们使用 dnsmasq 的要求。
解法:
sudo systemctl disable systemd-resolved
sudo rm -f /etc/resolv.conf # manually delete the /etc/resolv.conf
sudo systemctl reload NetworkManager # NM will regenerate /etc/resolv.conf