VPN Subnet routing – Strange behavior.

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This topic contains 5 replies, has 0 voices, and was last updated by  matth 9 years, 9 months ago.

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  • #41631

    matth
    Member

    I am running ZeroShell on an ALIX platform.

    I had a strange experience with routing and openVPN and I want to hear opinions on why this happened.

    When I initially setup my network, I did it in the following manner:

    DMZ ETH0  -> no link
    LAN ETH1 -> 192.168.3.0/24 .1
    WAN ETH2 -> x.x.x.x/29
    VPN VPN99 -> 192.168.250.0/24 .254

    When setup as such everything functions properly.

    Due to a subnet conflict with a remote site, I changed my subnets as follows:

    DMZ ETH0  -> no link
    LAN ETH1 -> 172.16.42.0/24 .1 *******
    WAN ETH2 -> x.x.x.x/29
    VPN VPN99 -> 192.168.250.0/24 .254

    This setup would not pass any traffic to or from the VPN tunnel.

    After a lot of swearing, I changed the setup to the following and everything worked.

    DMZ ETH0  -> no link
    LAN ETH1 -> 172.16.42.0/24 .1
    WAN ETH2 -> x.x.x.x/29
    VPN VPN99 -> 172.16.250.0/24 .254 *******

    Any thoughts as to why VPN would work as one subnet and not another?

    Matt

    #48011

    yum
    Member

    Maybe firewall configuration is an issue?

    #48012

    matth
    Member

    My firewall was set to accept all traffic.

    #48013

    This is basic “Static Routing 101”. Not a firewall issue or even a zeroshell issue.

    #48014

    yum
    Member

    Do you mean this http://staros.tog.net/wiki/Routing_101 example?

    So adding static route to remote LAN via VPN IP on the VPN client side will resolve this issue?

    Thank you

    #48015

    ppalias
    Member

    Most likely the remote site had a static route for 172.16.0.0 only, so the VPN tunnel could not be routed. Are you using any RIP for the dynamic routing?

    #48016

    yum
    Member

    I’m just curious. It’s matth’s problem, not mine. Thank you.

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