Re: Slightly OT: VNC Connections
- From: "Graham J" <graham@xxxxxxxxxxxxxxxx>
- Date: Mon, 19 May 2008 23:04:17 +0100
"Christian" <deadend@xxxxxxxxxxxxxxx> wrote in message
news:4831a9e4$0$26087$db0fefd9@xxxxxxxxxxxxxxxxx
On Mon, 19 May 2008 15:45:04 +0100, Graham J wrote:
Is the internal IP address of your network different from the internal
address of the remote network? (i.e you can't both have 192.168.0.0 / 24
for example)
Are you sure about this? The router is usually doing NAT, why would the
LAN range matter?
You're right, it doesn't matter.
I thought about it this way:
Assume both sites have a router, remote PC has IP=192.168.0.1 and local PC
has IP=192.168.0.2
Run ping on remote PC.
Packet starts out wth source ip=192.168.0.1 and destination IP as the
external address of OP's router. Because the destination adddress is
outside the local network, ARP arranges to deliver the packet to the default
gateway i.e. the local router.
Packet leaves remote LAN. NAT will occur in the router and the source
address of the packet is modified to show the external IP address of the
remote site. The packet thus appears to originate from that address; it
carries no information about its original source.
Packet traverses internet and arrives at external port of OP's router.
OP's router has port forwarding, so modifies the destination address of the
packet to 192.168.0.2. ARP arranges to deliver the packet to the PC.
The PC replies, to the source address found in the incoming packet, i.e. the
external IP address of the remote site. The packet goes to the local
router, which sends it out to the internet.
Reply packet arrives at the external port of the remote router. NAT checks
the sequence number to verify that the packet is a valid reply to the one it
sent out, if happy, looks up the table of outgoing traffic to find the IP
address of the machine that originated the packet, edits the destination
address accordingly and delivers the packet to the LAN port, from where ARP
delivers it to the correct PC.
So the reason for the OP's problem is either that he has misconfigured
something, or that the traffic is not travelling from one external IP to the
other.
Traceroute should show where the traffic is going. Try it from each site,
ideally simultaneously. The route may well not be the same in both
directions, but it should converge at each end on the relevant router. Try
it to and from other sites; see what commonality exists.
-- Graham J
.
- References:
- Slightly OT: VNC Connections
- From: Mark Carver
- Re: Slightly OT: VNC Connections
- From: Graham J
- Re: Slightly OT: VNC Connections
- From: Christian
- Slightly OT: VNC Connections
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