Windows subnets

Andrew Savinykh andrews at brutsoft.com
Thu Oct 7 03:26:56 CEST 2010


  Awesome! Now I think I finally understand how to do this. Thank you 
very much. (Just to confirm, I need to assign the new additional IP on 
physical adapter for each non tinc PC and on tap adapter for tinc 
gateway PCs, right?)

Andrew.

On 7/10/2010 2:14 p.m., Donald Pearson wrote:
> Sure it's possible, you just need to assign each node a new IP in the 
> 10.30.1.0/24 <http://10.30.1.0/24> network.  It's not part of the Tinc 
> configuration, it's part of the network configuration of each computer.
>
> All Tinc is doing, is creating a layer 2 path for them to reach each 
> other.  Yes broadcasts will traverse the VPN.  It literally is virtual 
> ethernet over the internet.  :)
>
> On Wed, Oct 6, 2010 at 9:04 PM, Andrew Savinykh <andrews at brutsoft.com 
> <mailto:andrews at brutsoft.com>> wrote:
>
>     Donald, thank you for this.
>
>     Do i read you right that to be able to receive broadcasts across
>     LANs I have to use the address space that I already have and make
>     sure that this space is the same for both LANs?
>
>     What I'm trying to do is to define a *completely new subnet* that
>     will act as the common LAN foR both LAN A and LAN B.
>
>     To re-iterate:
>     I have one router that is 10.1.1.1 and gives out DHCP 10.1.1.* and
>     the other router 192.168.0.1 that gives out DHCP 192.168.0.*.
>     I would like to leave these address spaces alone and define a new
>     on 10.30.1.* that computer from both networks can participate in
>     effectively forming a new virtual LAN.
>
>     Is this possible with tinc? I know this possible with other
>     software, I'm just having hard time figuring out if this is
>     something I can configure tinc to do.
>
>     Andrew
>
>
>
>
>     On 7/10/2010 1:13 p.m., Donald Pearson wrote:
>>     Sorry you're right.  I was looking at the IP address schema where
>>     all nodes would use the 10.30.0.0/24 <http://10.30.0.0/24> network.
>>
>>     There's no need to install tap adapters on the other devices. 
>>     You have basically 2 realistic options if you want the LAN function
>>
>>     You can specify multiple IP addresses for a single interface,
>>     even in Windows.  You'll find this under the TCP/IP properties of
>>     the network adapter.  And clicking on the Advanced button on the
>>     page where you can set a static IP or designate DHCP.
>>
>>     A 2nd option would be to re-ip one of your locations so that they
>>     all use the same subnet natively.
>>
>>     Bridging the tap adapter allows your network frames received by
>>     your physical interface to reach the TAP adapter and therefore
>>     traverse the VPN.  This enables later 2 connectivity, the same
>>     way a real switch does.  Virtual Ethernet over the Internet is
>>     how I like to describe it.  This is how I have my VPN configured
>>     personally.
>>
>>     Without the bridge, a frame that is received at the physical
>>     interface has the frame stripped off and the packet inspected. 
>>     Now we're talking layer 3.  If the packet is destined for a
>>     network on the other side of the VPN, your Tinc node frames the
>>     packet back up with a new frame, and sends it over the VPN.  
>>     This act of stripping the frame, reading the packet for the
>>     network destination, and applying a new frame to get it there is
>>     what Routing is.  Without the bridge in place, your Tinc node is
>>     literally routing between the physical interface and the tap
>>     interface.  With the bridge, you're creating a layer 2 pathway so
>>     the frames can shoot across directly.  Of course this means both
>>     sides need to be on the same subnet which you obviously already know.
>>
>>     Be warned that this configuration comes with it's drawbacks. 
>>     DHCP will traverse your VPN.  I had location A computers getting
>>     addresses from location B which makes for some really inefficient
>>     internet traffic.
>>
>>     Regards,
>>     Donald
>>     On Wed, Oct 6, 2010 at 7:57 PM, Andrew Savinykh
>>     <andrews at brutsoft.com <mailto:andrews at brutsoft.com>> wrote:
>>
>>         Donald, thank you for the explanation.
>>
>>         I understand the part about the switch mode and absence of
>>         subnet in tinc.config.
>>         However, could you please explain what bridging the tap
>>         adapter will achieve and what kind of ip address will be used
>>         on tinc nodes and in the rest of the network.
>>
>>         In my example one household has local network addresses of
>>         192.168.1.* and the other has 10.1.1.*
>>         If we don't install tap interfaces on other PC's this means
>>         that the other PCs won't have another ip address.
>>         I understand that bridging is going to solve this somehow,
>>         but I still don't see how broadcast from 10.1.1.7 can reach
>>         192.168.1.5 in the other LAN.
>>
>>         In short I don't understand how bridging to adapters work.
>>         I'll try to google this topic to get a better understanding,
>>         meanwhile, could you please explain
>>         how this applies to our tinc configuration case.
>>
>>         Also can you briefly describe what we achieve by setting
>>         PMTUDiscovery = Yes. I read the description in manual but it
>>         didn't tell me much.
>>
>>         Thank you again for all your help,
>>         Andrew
>>
>>
>>
>>
>>         On 7/10/2010 11:40 a.m., Donald Pearson wrote:
>>>         Oh okay.  Yes you can make it appear as a single LAN.  Your
>>>         Tinc nodes will behave as bridges instead of routers (or
>>>         gateways as you put it).
>>>
>>>         Your tinc nodes will have the same subnet mask and default
>>>         router as all your other devices at that location.
>>>
>>>         You will need to run the add-tap script only on the tinc
>>>         nodes on each side.
>>>
>>>         You will then need to bridge the tap adapter to the local
>>>         area connection on the tinc nodes on each side.
>>>
>>>         This will create a bridge network object under your network
>>>         connections.  This bridge will have the IP configuration you
>>>         illustrated.
>>>
>>>         You have the right idea in segregating the IP distribution
>>>         while still using the 255.255.255.0 subnet mask.
>>>
>>>         One both nodes are up and connected, and the interfaces have
>>>         been bridged on the Tinc nodes for each location, you will
>>>         have a virtual LAN between the two locations.
>>>
>>>         Your Tinc configuration will be Switch mode.   This means no
>>>         Subnet configurations are required in your tinc.conf
>>>
>>>         Your tinc.conf will be something like
>>>
>>>         Name = NodeA
>>>         ConnectTo = NodeB
>>>         Interface = <something>
>>>         Mode = switch
>>>         PrivateKeyFile = <path to the rsa_key.priv>
>>>
>>>         Host files will be something like
>>>         For the host file named "NodeA"
>>>
>>>         Address = <host.dyndns.org <http://host.dyndns.org>>
>>>         PMTUDiscovery = Yes
>>>
>>>         --Begin RSA etc. etc.--
>>>
>>>
>>>         On Wed, Oct 6, 2010 at 6:17 PM, Andrew Savinykh
>>>         <andrews at brutsoft.com <mailto:andrews at brutsoft.com>> wrote:
>>>
>>>             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 <http://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 <http://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 <http://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 <http://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 <http://10.10.10.0/24>
>>>>
>>>>             At a location, one computer 192.168.1.254/24
>>>>             <http://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 <mailto: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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