Windows subnets

Donald Pearson donaldwhpearson at gmail.com
Thu Oct 7 01:57:29 CEST 2010


For layer 3 routing this is all true.

For later 2 switching this isn't the case.  With Tinc mode is set to switch,
both sides sharing the same subnet, and the Tinc endpoints act similarly to
a bridge, all nodes within the subnet on both sides of the VPN will
effectively see each other as peers on the same LAN.  No new routes are
required.  There is no special VPN subnet, there is no special network
configuration on any devices unless you consider the bridge configuration on
the Tinc nodes to be special.

Either way works for connectivity, but I think Andrew is looking for the
layer 2 solution.


On Wed, Oct 6, 2010 at 6:52 PM, Alan S. Lawee <info at polygration.com> wrote:

>  In order for you to configure this, you have to set up explicit routes,
> and the computers in each location that are hosting the tinc application
> must be able to route packets.
>
>
>
> A little more explanation is in order. As you are referring to the nodes as
> PC’s, I am assuming that you are using the MsWindows operating system.  Some
> versions (e.g. Windows 2000) are able to function as routers out of the box,
> others cannot function as routers, and yet others require some advanced
> configuration. (Linux or other x-based systems can all function as routers).
>
>
>
> Computers on LAN A are configured to use the broadband router as a default
> gateway in order to access the Internet.  However, in order to accomplish
> the configuration you are looking for, you will have to set up a manual
> route on each of the computers on LAN A which will instruct them to go to
> the computer running tinc in order to reach the nodes on LAN B.  The reverse
> will be true for the computers on LAN B.
>
>
>
> Your IDEA1 will not work because the subnet masks do not define distinct
> networks.  IDEA2 has the same problem because the tinc subnet is not
> distinct from the other 2.
>
>
>
> So, to follow your example IDEA2, we have in household A, LAN A: 10.30.1.x
> and 3 PC’s: PC-A.11, PC-A.12 & PC-A.13, plus a router: R-A.1;  in household
> B, LAN B: 10.30.2.x, we have a similar configuration, PC-B.11, PC-B.12,
> PC-B.13 and R-B.1;  the tinc application is hosted on each of PC-A.11 and
> PC-B.11 and will use the subnet 10.30.3.x.
>
>
>
> As an example, the IP configurations are as follows:
>
>
>
> PC-A.11:                               Default Gateway
> 10.30.1.1/255.255.255.0
>
>                                                 IP Address
> 10.30.1.11/255.255.255.0 on physical network interface
>
>                                                 IP Address
> 10.30.3.1/255.255.255.0 on virtual tinc interface
>
>                                                 Manual entry in routing
> table to 10.30.2.0/255.255.255.0 via 10.30.3.2
>
>
>
> PC-A.12, PC-A.13:            Default Gateway 10.30.1.1/255.255.255.0
>
>                                                 IP Address
> 10.30.1.12/255.255.255.0 and 10.30.1.13/255.255.255.0
>
>                                                 Manual entry in routing
> table to 10.30.2.0/255.255.255.0 via 10.30.1.11
>
>
>
> PC-B.11:                               Default Gateway
> 10.30.2.1/255.255.255.0
>
>                                                 IP Address
> 10.30.2.11/255.255.255.0 on physical network interface
>
>                                                 IP Address
> 10.30.3.2/255.255.255.0 on virtual tinc interface
>
>                                                 Manual entry in routing
> table to 10.30.1.0/255.255.255.0 via 10.30.3.1
>
>
>
> PC-B.12, PC-B.13:             Default Gateway 10.30.2.1/255.255.255.0
>
>                                                 IP Address
> 10.30.2.12/255.255.255.0 and 10.30.2.13/255.255.255.0
>
>                                                 Manual entry in routing
> table to 10.30.1.0/255.255.255.0 via 10.30.2.11
>
>
>
> Now every PC knows where to send packets destined for both the Internet and
> the other household.  The PC’s hosting tinc are acting as the virtual
> routers between the two sites.  Note once again that various versions of
> Windows have this routing function disabled.
>
>
>
> Hope this helps you,
>
> Alan
>
> *From:* tinc-bounces at tinc-vpn.org [mailto:tinc-bounces at tinc-vpn.org] *On
> Behalf Of *Andrew Savinykh
> *Sent:* Wednesday, October 06, 2010 18:17
> *To:* tinc at tinc-vpn.org
> *Subject:* Re: Windows subnets
>
>
>
> Donald,
>
> thank you, while I still have some questions, your answer is definitely a
> step in the right direction.
> In the other reply I was asked what I'm trying to achieve. Let's consider
> the following scenario (which is quite similar to the one that described in
> the tinc manual).
>
> Let's assume we have two households, each has 3-5 computers in it.  Both
> house holds have similar network configuration:
> They are connected to internet with an ADSL line and a router.
> The computers in the local network access internet via the router.
> The router is configured so that one of the computers have port 665
> forwarded to be accessible outside.
> The external IP is changed rarely and there is dynamic DNS service
> (external) in use to accommodate for the change of IP when it happens.
>
> One household has local network addresses of 192.168.1.* and the other has
> 10.1.1.*
> I'm installing tinc on one computer in each household.
>
> The goal is to let all computers in both house holds to see each other by
> ip address. Also it is desired that for computer games purposes
> all computers appear to be on the same LAN (for broadcasts). But this is
> not mandatory. (it appears that it's not possible without installing tinc on
> every PC
> as every tinc daemon serves a subnet and two tinc daemons can't serve a
> part of subnet each)
>
> All computers run different flavours of Windows, most being Windows 7.
>
> I have two ideas how to set this up, although I'm not sure if any of these
> two works:
>
> IDEA1.
> =====
> Household A
> Gateway IP: 10.30.0.1
> Gateway Mask: 255.255.255.0
> Gateway Default Gateway: ????
>
> Other PCs IP: 10.30.0.2,3,4 etc
> Other PCs Mask: 255.255.255.0
> Other PCs Deafult Gateway: 10.30.0.1
>
> Tinc Subnet: 10.30.0.0/25
>
> Household B
> Gateway IP: 10.30.0.129
> Gateway Mask: 255.255.255.0
> Gateway Default Gateway: ????
>
> Other PCs IP: 10.30.0.130,131,132 etc
> Other PCs Mask: 255.255.255.0
> Other PCs Default Gateway: 10.30.0.129
>
> Tinc Subnet: 10.30.0.128/25
>
>
> IDEA2.
> =====
> Household A
> Gatway IP: 10.30.0.1
> Gateway Mask: 255.255.255.0
> Gateway Default Gateway: ????
>
> Other PCs IP: 10.30.0.2-255 etc
> Other PCs Mask: 255.255.255.0
> Other PCs Default Gateway: 10.30.0.1
>
> Tinc Subnet: 10.30.0.0/24
>
> Household B
> Gateway IP: 10.30.1.1
> Gateway Mask: 255.255.255.0
> Gateway Default Gateway: ????
>
> Other PCs IP: 10.30.1.2-255 etc
> Other PCs Mask: 255.255.255.0
> Other PCs Default Gateway: 10.30.0.129
>
> Tinc Subnet: 10.30.1.0/24
>
>
> So IDEA 1 probably won't work at all. Will it? And with IDEA 2 the pc's
> won't appear on the same LAN and their broadcasts won't reach each other.
> As far as I understand I need to install TAP interface on each of the
> participating windows PCs, correct?
> What is specified in default gateway of the gateways?
>
>
> Thank you in advance,
> Andrew
>
> On 7/10/2010 4:36 a.m., Donald Pearson wrote:
>
> The PCs that you want to participate need to have a route for the VPN
> subnet pointing to their local VPN gateway, which would be the local device
> with Tinc installed on it.
>
>
>
> Theoretical configuration example.
>
>
>
> VPN subnet is 10.10.10.0/24
>
>
>
> At a location, one computer 192.168.1.254/24 connects to the VPN and
> serves as the VPN gateway.  This gateway needs to be configured for TCP/IP
> forwarding.
>
>
>
> http://support.microsoft.com/kb/315236 - windows
>
> http://www.ducea.com/2006/08/01/how-to-enable-ip-forwarding-in-linux/ -
> linux
>
>
>
> Other computers local to the gateway need a route to the VPN network added
> so they know how to get there.
>
>
>
> In windows.   route -p add 10.10.10.0 mask 255.255.255.0 192.168.1.254
>
> This will add the persistent route that remains after reboot.
>
>
>
> Does that answer your question?
>
>
>
> On Wed, Oct 6, 2010 at 6:41 AM, Andrew Savinykh <andrews at brutsoft.com>
> wrote:
>
> Thank you for your reply. As far as I can see there is no point specifying
> subnet that consists of more than one PC in tinc config if you are going to
> install tinc on every PC in the subnet anyway. Correct me if I'm wrong.
> Now, assuming I'm right, there will be PCs in the subnet that don't have
> tinc installed on them. How to configure these PCs so they are a part of the
> subnet and participate in routing?
>
> Cheers,
> Andrew
>
>
>
> On 6/10/2010 10:13 p.m., Cédric Lemarchand wrote:
>
>  Hi,
>
> I am not sure to understand what you mean with "joining" a subnet.
>
> But if your "local computer" need to reach the "remote subnet" served by
> tinc, you can set the local IP of the local tinc server as the default
> gateway, or add a route to the remote subnet via the local tinc IP. Of
> course, computer located on the remote subnet need the same thing.
>
> Cédric
>
> Le 06/10/10 09:37, Andrew Savinykh a écrit :
>
>  Hello all,
>
> I understand that each tinc daemon corresponds to one or more subnets that
> it "owns" a subnet can be a single ip or more.
> Could you please tell me what do I need to do to join a computer in local
> network (windows) to a subnet served by tinc?
>
> Thank you in advance,
> Andrew
>
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>
> --
>
> *Cédric Lemarchand – iXSea SAS*
>
> Administrateur Système & Réseaux
>
> http://www.ixsea.com/ - <cedric.lemarchand at ixsea.com><cedric.lemarchand at ixsea.com>
>
> Tel: +33 1 30 08 8888 – GSM: +33 6 37 23 40 93
>
>
>
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