Connecting to local subnet issue



  • During the testing of pfsense openvpn server I faced issues in pinging machines in subnet of pfsense server.

    Setup
    –-------

    • Internet router provided by ISP. IP: 192.168.1.254
    • My Laptop. Ubuntu 9.04. IP: 192.168.1.105
    • pfsense running as a virtual machine (vmware player). WAN IP: 192.168.1.239, LAN IP: 192.168.1.233
    • Another virtual machine (vmware player) running with IP: 192.168.1.209

    OpenVPN Setup

    • TUN interface
    • Tunnel network: 10.0.9.0/24
    • push "route 192.168.1.0 255.255.255.0" in place

    Test

    OpenVPN client on Windows XP tries to connect to openvpn server & tries to ping 192.168.1.209

    Observations

    • Connection with the openvpn server gets successfully established.
    • Client can ping 192.168.1.239 & 192.168.1.233 addresses.
    • Client is also able to ping 192.168.1.105 (the machine on which the pfsenseissue vm is running)
    • But client is not able to ping 192.168.1.209 (another virtual machine) or 192.168.1.254 (internet gateway on server side)

    I dont know why such behavior is observed. Appreciate if anybody can offer some explanation.

    Thanks

    Chetan S.



  • I was able to solve the issue by changing the LAN IP Address to 192.168.10.233. The problem is that if WAN & LAN ips are in same subnet then the problem occurs as soon as I change the LAN IP to say 192.168.10.209 then client is able to ping the 192.168.10.209 host. Can someone please explain why this happens.



  • It's just basic routing. A router that is connected to two or more different networks has to be able to tell the networks apart somehow, it can not guess where to send the packets if two networks have ip address that overlap.


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