How can I use Ubuntu as a gateway into a remote LAN?

Question

I need to be able to access whole remote subnets from a Windows PC. Here's my network layout:

I -{MyLAN: 10.77.77.0/24, DHCP}--[Ethernet: 10.77.77.64]
N                                  (Windows 10 Home PC)
T -{Hama           }----[Hamachi: 25.77.47.206, basically static]
E  {    chi        }
R  {        netw   }
N -{            ork}---[Hamachi: 25.142.124.197, basically static]
E                                 (Ubuntu Server 15.10)[enx00249b170da2: 192.168.0.67]+
T -{LAN2: 192.168.0.0/24, DHCP}-[enp3s0: 192.168.0.67]                                |
                                                        {LAN3: 192.168.1.0/24, static}+

1. Windows and Ubuntu can both connect to each other.
2. Using iptables nat for simple forwarding of a port, Windows PC can connect to specified resources in LAN2 and LAN3 at 25.142.124.197

3. Windows route print output:

   Persistent Routes:
     Network Address          Netmask  Gateway Address  Metric
             0.0.0.0          0.0.0.0       10.77.77.1  Default
         192.168.1.0    255.255.255.0   25.142.124.197       5
         192.168.0.0    255.255.255.0   25.142.124.197       5
   

4. Ubuntu route output:

   Kernel IP routing table
   Destination   Gateway      Genmask         Flags Metric Ref  Use Iface
   default       192.168.0.1  0.0.0.0         UG    0      0    0   wlp2s0
   25.0.0.0      *            255.0.0.0       U     0      0    0   ham0
   192.168.0.0   *            255.255.255.0   U     0      0    0   wlp2s0
   192.168.1.0   *            255.255.255.0   U     0      0    0   enx00249b170da2
   

5. sysctl net.ipv4.conf.default.forwarding net.ipv4.conf.all.forwarding:

   net.ipv4.conf.default.forwarding = 1
   net.ipv4.conf.all.forwarding = 1
   

6. All nat and filter iptables chains are empty and set to ALLOW

7. LAN2 TP-Link router (192.168.0.1) has a 'Static Route' enabled:

   25.0.0.0   255.0.0.0 -> 192.168.0.67
   

I am looking for both a solution where NAT is used, because that is the only way I can access devices without setting static routes on subnet routers, and a solution without NAT, for full 2 way connectivity (LAN2/3 members to Windows Home PC and vice versa)

I can not reasonably put 2 new tunnels inside the Hamachi VPN and bridge those to the subnets because both subnets are on a low-signal mobile uplink with no public ip, resulting in very low bandwidth (and even further latency due to 'relayed tunnel' operation)

Answer 1

Zerotier can do layer 2 bridging. You'd install it on your windows machine and the ubuntu machine and enable bridging in the ubuntu machine's zerotier config. This is nice because broadcast discovery stuff would work. You could also use "full tunnel" mode.