On Wednesday, February 12, 2003, at 10:40 AM, David Wilburn wrote:
I've been attempting to beef up my knowledge of IPsec recently, and got to thinking hypothetically about a *possible* problem with implementing IPsec on larger networks. My experience with IPsec is currently limited at best, so hopefully I can communicate this properly:
Let's assume that I have a large-ish network with multiple connections to the Internet and ambiguous routing (meaning that a packet might come in one gateway and the response packet might leave through a different gateway). Let's also assume that I'd like to allow IPsec tunnels into my network to allow single workstations and small networks to attach to mine.
With such ambiguous routing, is my understanding correct that the response traffic could potentially bypass the VPN concentrator altogether and travel to the destination unencrypted?
Well, if it's routed then it's reachable, whether or not the packets are encrypted or unencrypted. But, that doesn't mean the unencrypted traffic needs to be permitted beyond your gateways. The security association includes the source address, so you can create policies that disallow traffic except from expected hosts. As for ambiguous (asymmetric?) routing, the tunnel is, for all intents and purposes, unaware of the underlying transport architecture, so it shouldn't make any difference as long as you have decent performance on your network as a whole. We use IPSec tunnels across the internet all the time and they work great.
Are there any solutions for quickly, reliably, and securely sharing IPsec Security Association databases between gateways, so that the other gateways would know to encrypt the traffic before letting it out?
How about setting up your own Certificate Authority. Mike ------------------------------------------------------------------------ -- Michael K. Smith NoaNet 206.219.7116 (work) 206.579.8360 (cell) mksmith@noanet.net http://www.noanet.net