Re: RV042 - Does anyone understand it? Documentation?
- From: "Fred Marshall" <fmarshallx@xxxxxxxxxxxxxxxxxxxx>
- Date: Sun, 1 Jul 2007 22:22:53 -0700
"Mike Drechsler - SPAM PROTECTED EMAIL"
<mike-newsgroup@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
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Fred Marshall wrote:
"Mike Drechsler - SPAM PROTECTED EMAIL"
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Fred Marshall wrote:
I'm using RV042s for VPNs and general routing. Often there areapparently it's supposed to be obvious.
questions but seem to be no place for answers.
For example: if one is using an RV042 for VPN, then what affect does
the routing table have on the VPN packets?
Is there any place where this sort of thing is reasonably described?
Or, is the answer to this one question supposed to be obvious?
Fred
It does help to have prior experience with setting up IPSEC VPN tunnels
and a good understanding of how it works.
Routing tables will have limited use when you are trying to move
traffic. A routing table will not affect the contents or intended
contents of an encrypted packet.
If you want to give an example of what you are attempting to setup then
perhaps you will find some help.
Mike,
thanks for the reply.
I can envision the VPN "block" running in series or in parallel with the
routing table "block". In the first case, on the incoming /
post-decryption end. In the second case, totally independent. Not much
else makes sense to me but I sure can be enlightened.
What I've been trying to do is like this:
Launch a packet destined for a "foreign" private subnet.
Route such packets at their source to the LAN address of the RV042 VPN
router.
From there over the internet.
When the packet is received at the other end of the tunnel, it will still
be destined for a "foreign" private subnet.
i.e. the packet is destined neither for the local nor the remote subnet.
So, I add a route on the receiving RV042 that points such packets to a
gateway on the remote LAN. If this works then such packets should be
directed to that gateway. But, it doesn't seem to work.
Here are the addresses involved:
Source: 192.168.113.130 Destination 192.168.1.4
255.255.255.224 Route for destination: 192.168.113.157 the
RV042 VPN
(I guess at this point there is no route in the RV042 for this address
range. Can the RV042 routing table route packets into its own VPN? I
don't see how). So, this could be a problem I guess. The destination
*is not* in the VPN remote LAN range.
(internet)
RV042 VPN 192.168.113.198 w/Route: 192.168.1.0 /24 > 192.168.113.254
255.255.255.192 255.255.255.192
has port
on:192.168.1.0/24
It appears that the packets don't arrive at the destined router on the
remote LAN.
If the RV042 routing table does not deal with unencrypted packets coming
out of the VPN then this method wouldn't be expected to work. It would
really help to know what to expect without running a bunch of
experiments.
Or, maybe the VPN-initiating RV042 doesn't accept packets thus destined -
as they are on different subnets? My confusion here is that there's a
remotely managed Cisco router on site that does pretty much the same
thing. It takes the packets and routes them to appropriate ports just
fine (and for a lot more $$).
Fred
The VPN endpoints will not encrypt any traffic that is not included in a
security association. In other words the range of IP's you are trying to
reach and the range of IP's the traffic is coming from MUST be included in
the subnets for the encrypted tunnel. You cannot use the encrypted tunnel
as a route where arbitrary packets can enter on one side and exit the
other side. IPSEC is meant as an end to end ecryption mechanism so it
will refuse any traffic that is not specifically included in the subnet
ranges that were used to build to the tunnel.
So I'm looking at the VPN Tunnel settings on an RV082 which I assume has
the same user interface as the rv042. Where it says Local and remote
security group type, IP address, and subnet mask. These will define the
range of IP's that will go through the tunnel connection. The solution
would be to either create a larger range of IP's to include in the local
and remote subnets or if that is not practical then create a second tunnel
with a different set of remote and local IP's that will be sent encrypted
to the other router.
I'm sorry I cannot comment on your specific examples. I have no clue what
you are trying to do with the IP's you listed, it's simply not clear to me
the way you wrote things down.
Here is a simple example.
So the basic case is you create a VPN tunnel that connects the
192.168.100.0/24 subnet in your estern office with the 192.168.200.0/24
subnet on the other site at your western office. This is the simple case
and you would simply follow the examples in the documentation.
192.168.100.0/24(east)->RV042->Internet<-RV042<-192.168.200.0/24(west)
Now you are saying that you have multiple subnets in each office and you
want to route the traffic to the tunnel. So you are assuming that you can
just create a static routing table entry to point the traffic to the IP of
the router on the other end of the tunnel and you expect that the packet
would end up inside the tunnel as a result
So you have built a tunnel using the simple case example above.
Now you create a static route in the east that looks something like this:
You want:
192.168.101.0/24->192.168.100.1->INTERNET->192.168.200.1->192.168.201.0/24
On the east side you create a static route that says Destination ip:
192.168.201.0/24 (a subnet in the other office) uses gateway 192.168.200.1
(Internal IP of the router on the other site)
On the west side you create a similar static route that says Destination
ip: 192.168.101.0/24 uses gateway 192.168.100.1
But this will not work because these source and destination IP's are not
part of the original subnets of the tunnel they will not be encrypted or
sent across the tunnel.
What you need to do is create 2 parallel tunnels that go between the same
routers with different local and remote subnets.
192.168.100.0/24(east)->RV042->Internet<-RV042<-192.168.200.0/24(west)
192.168.101.0/24(east)->RV042->Internet<-RV042<-192.168.201.0/24(west)
Also the subnet definitions of the tunnel do not need to exactly match the
LAN subnet on the other side. You can make these larger as long as the
range of IP's in the larger subnet range is still correct for the remote
site. Also you can use expanded subnet ranges to create hub and spoke
configurations where one central site creates single tunnels to each
branch office and if one branch office wants to communicate with another
branch office then the traffic flows to the central site first where it is
redirected to another tunnel to the second branch site. This requires good
planning but it saves you from creating a tangled mess of tunnels for
sites that rarely need to communicate directly.
A good example would be:
Central site: 192.168.100.0/24
Branch 1: 192.168.110.0/24
Branch 2: 192.168.120.0/24
Branch 3: 192.168.130.0/24
etc.
To create a hub and spoke configuration you would create a tunnel like
this:
Local security group: 192.168.110.0/24
Remote security group: 192.168.0.0/16 (The remote range is for
192.168.0.0-192.168.255.255)
So now you send a packet from branch 1 to branch 2.
eg: source: 192.168.110.15 -> dst: 192.168.120.55
So this causes your router to send any traffic that is not for the local
lan on a private IP in the 192.168.0.0 range off through the encrypted
tunnel. When it reaches the other end that central router will evaluate
the packet after decrypting it and if it is for it's local lan it will
forward it to the LAN. If not then it will evaluate the packet to see if
it matches another tunnel. It will find that a tunnel with a remote
subnet of 192.168.120.0/24 exists and that this packet also matches the
local security group definition so it is to be encrypted in the tunnel. It
resends the packet to branch 2. The branch 2 router decrypts the packed
and finds the destination is for the local subnet so it forwards it to
it's LAN.
You can think of these tunnel definitions as another layer of routing that
happens before the traditional routing table is evaluated.
Mike,
Thanks.
Well the point of my question was about how the RV042 works. I'm becoming
rather convinced that if it's being used as a VPN device then the static
routes one might enter will have no affect.
Fred
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