ssh-vpn-share-admin-inet.sh

#!/usr/bin/env bash

host="$1"
disconnect="$2"
local_tun_number="1"
home_tmp=
eval home_tmp=~"$USER"/.ssh/tmp.sockets

mkdir -p "$home_tmp"

if [[ -n "${disconnect:+x}" ]]; then
  ssh -q -S "$home_tmp"/"$host".ssh.sock -O exit "$host" '' &
  sysctl -w net.ipv4.ip_forward=0 >/dev/null &
  iptables -t nat -D POSTROUTING -s 10.0.0.1 -j MASQUERADE 2>/dev/null
  systemctl start firewalld
else
  ssh -q -o BatchMode=yes -i ~"$USER"/.ssh/id_rsa -o StrictHostKeyChecking=accept-new "$host" 'sed -i -e "s|.*PermitTunnel.*|PermitTunnel point-to-point|" /etc/ssh/sshd_config ; systemctl restart sshd; sed -i "1inameserver 8.8.8.8" /etc/resolv.conf ;exit'
  ssh -q -f -N -M -S "$home_tmp"/"$host".ssh.sock -i ~"$USER"/.ssh/id_rsa -w "$local_tun_number" "$host" ''
  ssh -q -o BatchMode=yes -i ~"$USER"/.ssh/id_rsa "$host" 'ip a add 10.0.0.1/30 dev tun0 peer 10.0.0.2 ; ip l set tun0 up ; ip r add "${SSH_CONNECTION%%" "*}" via "$(ip r | grep default | cut -f3 -d " ")" dev "$(ip r | grep default | cut -f5 -d " ")" 2>/dev/null ; ip r add default via 10.0.0.2 dev tun0 metric 1'

  ( ip a add 10.0.0.2/30 dev tun"$local_tun_number" peer 10.0.0.1 && ip l set tun"$local_tun_number" up ) &
  sysctl -w net.ipv4.ip_forward=1 >/dev/null &
  systemctl stop firewalld
  iptables -t nat -A POSTROUTING -s 10.0.0.1 -j MASQUERADE
fi
exit 0