tailscale exit node settings and global dns settings

tailscale exit node settings and global dns settings

0.In my 0th vps (for example Oracle Cloud free tier VPS, ubuntu 20.04, it allow me to create 2 free vps servers): 
    sudo apt install tailscale(ref: https://tailscale.com/kb/1039/install-ubuntu-2004/)
    sudo tailscale up    //copy the showed url and authorize google sign-in in the web  browser
    ip addr show tailscale0       //for example: 100.71.153.9

1. In my 1st vps(in china, for example my linux PC in my home):
     sudo apt install tailscale
     sudo sysctl net.ipv4.conf.all.forwarding=1
     sudo tailscale up --advertise-exit-node --accept-dns=false    //copy the showed url and authorize google sign-in in the web  browser
     //"--advertise-exit-node" to advertise this vps as exit node, "--accept-dns=false" to avoid global dns settings overwriting /etc/resolv.conf in exit node
     ip addr show tailscale0           //it shows for example: 100.71.153.10
     curl https://www.google.com/search?q=my%20ip   //it shows for example: 132.226.172.5
     tailscale version                      //it shows 1.8.6
     //open socks5 proxy 8086 that go through the 0th vps
     while true; do nohup /usr/bin/ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -o ServerAliveInterval=10 -o ServerAliveCountMax=6 -CND 100.71.153.10:8086 ubuntu@100.71.153.9 -p 22 > /dev/null 2>&1; sleep 1; done &
     //create socks86 interface for 8086 socks5 proxy
     while true; do nohup ip tuntap add dev socks86 mode tun user nobody >/dev/null 2>&1; ifconfig socks6 up 10.6.0.1 >/dev/null 2>&1; badvpn-tun2socks --tundev socks86 --netif-ipaddr 10.6.0.2 --netif-netmask 255.255.255.0 --socks-server-addr 100.71.153.10:8086 >/dev/null 2>&1; sleep 1; done &
     ./mydns --listen 0.0.0.0:53      //my udp dns server, output every query logs, china/foreign IP split, for foreign IPs: ip route add <foregin ip>/32 dev socks86 scope link

2.In the web page of https://login.tailscale.com/admin/machines
     Click the "..." menu button of 100.71.153.10
     Click "Review route settings"
     Enable the "Use as exit node"

3.In the web page of https://login.tailscale.com/admin/dns
    Click "Add nameserver", input "100.71.153.10" and click "Save"
    Click the "Override local DNS" switch and enable it

4.In my android phone:
   Install latest tailscale app from google play(version >=1.8.6)
   Authenticate it with google sign-in
   Click the "..." menu button on the top-right of the app
   Click "Use "Use exit node" and select the name of "100.71.153.10"
   Click "Active" switch
   Open the browser,
   visit  https://www.google.com/search?q=my%20ip
   It shows my 1st oracle vps's IP 132.226.172.5

5.In my 2nd vps(in china, just for test, not must):
   curl  https://www.google.com/search?q=my%20ip      //it shows my 2nd vps's IP: 152.70.90.2
  sudo apt install tailscale
  sudo tailscale up --exit-node=100.71.153.10    //to restore: sudo tailscale down ; sudo tailscale up --reset
  curl  https://www.google.com/search?q=my%20ip --resolve www.google.com:443:216.58.200.36     //it shows my 1st vps's IP: 132.226.172.5
  Now I can see "/etc/resov.conf" has  been changed to "nameserver 100.71.153.10"
  I can see dns query log in my 1st vps