FWDing packets from a physical interface to a virtual interface

FWDing packets from a physical interface to a virtual interface

[Arash Yadegarnia]

Hi, :)

Here is the situation:

I have a machine with 2 NICs, assume eth0 (192.168.0.10) connected to my
LAN, and eth1 (192.168.0.20) connected to Internet through a gateway.
I also, have a virtual tap0 (TUN/TAP) interface (10.0.0.1) on this
machine.

All that I want to do is simply, forwarding ALL traffic coming to eth0
from the LAN, into my tap0 interface, So I can modify them using my own
user space program which can capture packets on the tap interface and
send them on eth1 to another address somewhere in the world (through
Internet).

Since I want IP addresses unchanged, I cannot use NAT or Masquerading.
As far as I know, In this matter forwarding should be done in Layer-2 so
I'm not sure if I can use iptables to do the job.
I also have tried bridging but I was trapped in a horrible bridge loop
(Enabling STP on bridge also didn't work for me).

Any ideas? :)

Thanks,
Arash

Re: FWDing packets from a physical interface to a virtual interface

[Jorge Davila]

Arash:

AFAIK, you must open a path in the firewall to the vpn daemon 
(port/protocol) and the daemon will be in charge of administering the 
traffic between the clients and the vpn server.

Additionally, you must tell to the client where is the server (the ip 
address), what device will be used (tun or tap device).

May you want ask in the mailing list for the vendor/provider of the vpn 
software that you are using.


Hope this helps,

Jorge Dávila.

On Wed, 12 Sep 2007 02:06:53 +0330
  Arash Yadegarnia <arash@bluehome.net> wrote:
> Hi, :)
> 
> Here is the situation:
> 
> I have a machine with 2 NICs, assume eth0 (192.168.0.10) connected to my
> LAN, and eth1 (192.168.0.20) connected to Internet through a gateway.
> I also, have a virtual tap0 (TUN/TAP) interface (10.0.0.1) on this
> machine.
> 
> All that I want to do is simply, forwarding ALL traffic coming to eth0
> from the LAN, into my tap0 interface, So I can modify them using my own
> user space program which can capture packets on the tap interface and
> send them on eth1 to another address somewhere in the world (through
> Internet).
> 
> Since I want IP addresses unchanged, I cannot use NAT or Masquerading.
> As far as I know, In this matter forwarding should be done in Layer-2 so
> I'm not sure if I can use iptables to do the job.
> I also have tried bridging but I was trapped in a horrible bridge loop
> (Enabling STP on bridge also didn't work for me).
> 
> Any ideas? :)
> 
> Thanks,
> Arash
> 
> 
> 

Jorge Isaac Davila Lopez
Nicaragua Open Source
+505 430 5462
davila@nicaraguaopensource.com

Re: FWDing packets from a physical interface to a virtual interface

[Arash Yadegarnia]

Thanks Jorge,

I'm not using any specific VPN solution, Me and my colleagues are
developing a secure VPN solution based on kernel TUN/TAP driver.
Since we have full control over our tap interface we just need to
redirect the whole traffic coming into the eth0 (from a LAN) into the
tap interface, so we can read them (I mean Ethernet frames in Layer 2)
and send them out from the other pysical interface (eth1).
BTW, Redirecting a single or even multiple ports won't work in my
situation, because I want whole traffic in layer 2, not a specific port
number.

Thanks,
Arash


On Tue, 2007-09-11 at 19:40 -0600, Jorge Davila wrote:
> Arash:
> 
> AFAIK, you must open a path in the firewall to the vpn daemon 
> (port/protocol) and the daemon will be in charge of administering the 
> traffic between the clients and the vpn server.

> Additionally, you must tell to the client where is the server (the ip 
> address), what device will be used (tun or tap device).
> 
> May you want ask in the mailing list for the vendor/provider of the vpn 
> software that you are using.
> 
> 
> Hope this helps,
> 
> Jorge Dávila.
> 
> On Wed, 12 Sep 2007 02:06:53 +0330
>   Arash Yadegarnia <arash@bluehome.net> wrote:
> > Hi, :)
> > 
> > Here is the situation:
> > 
> > I have a machine with 2 NICs, assume eth0 (192.168.0.10) connected to my
> > LAN, and eth1 (192.168.0.20) connected to Internet through a gateway.
> > I also, have a virtual tap0 (TUN/TAP) interface (10.0.0.1) on this
> > machine.
> > 
> > All that I want to do is simply, forwarding ALL traffic coming to eth0
> > from the LAN, into my tap0 interface, So I can modify them using my own
> > user space program which can capture packets on the tap interface and
> > send them on eth1 to another address somewhere in the world (through
> > Internet).
> > 
> > Since I want IP addresses unchanged, I cannot use NAT or Masquerading.
> > As far as I know, In this matter forwarding should be done in Layer-2 so
> > I'm not sure if I can use iptables to do the job.
> > I also have tried bridging but I was trapped in a horrible bridge loop
> > (Enabling STP on bridge also didn't work for me).
> > 
> > Any ideas? :)
> > 
> > Thanks,
> > Arash
> > 
> > 
> > 
> 
> Jorge Isaac Davila Lopez
> Nicaragua Open Source
> +505 430 5462
> davila@nicaraguaopensource.com
> 

Re: FWDing packets from a physical interface to a virtual interface

[Leonardo Rodrigues Magalhães]

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    So maybe you'll have to some bridging stuff and not 
netfilter/iptables ones ....

    iptables/netfilter deals basically with Layer 3 (IP) packets and not 
layer 2 frames, which are the ones you're interested.

Arash Yadegarnia escreveu:
> Thanks Jorge,
>
> I'm not using any specific VPN solution, Me and my colleagues are
> developing a secure VPN solution based on kernel TUN/TAP driver.
> Since we have full control over our tap interface we just need to
> redirect the whole traffic coming into the eth0 (from a LAN) into the
> tap interface, so we can read them (I mean Ethernet frames in Layer 2)
> and send them out from the other pysical interface (eth1).
> BTW, Redirecting a single or even multiple ports won't work in my
> situation, because I want whole traffic in layer 2, not a specific port
> number.
>
> Thanks,
> Arash
>   

-- 


	Atenciosamente / Sincerily,
	Leonardo Rodrigues
	Solutti Tecnologia
	http://www.solutti.com.br

	Minha armadilha de SPAM, NÃO mandem email
	gertrudes@solutti.com.br
	My SPAMTRAP, do not email it





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