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Netgear IPSec VPN passing through DSL modems?

I am trying to set up a VPN between two Netgear routers FVS318v3.

Router #1 is behind a managed Cable modem,
 - modem wan 100.101.102.103, modem lan 10.1.10.1
 - router wan 10.1.10.2, lan 192.168.15.1

Router #2 is behind a DSL modem,
 - modem wan 200.201.202.203, modem lan 192.168.1.1.
 - router wan 192.168.1.2, lan 192.168.22.1

Following FVS manual and other sources I tried to setup a VPN between the two. I tried opening / forwarding  through the modems ports
TCP 1723
TCP 47
UDP 500 for IKE
and UDP 1701

I must be missing some negotiation part, though - I am unable to establish conn.

Am I missing ports for IPSec VPNs? What else could cause the connection to fail?
0
Ronino
Asked:
Ronino
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3 Solutions
 
EvilKnievelCommented:
You've missed UDP 5500, the rest seems ok :)
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rr_haleCommented:
Standard IPSEC, uses UDP 500 and IP protocol 50 (ESP). Be sure NAT Traversal is enabled on both routers. Since you're going through a NAT device (managed cable modem), the IPSEC ESP packets will need to be encapsulated in UDP. NAT Traversal typically uses UDP 4500, but I've also seedn UDP 1500, as well.
Once NAT Traversal is enabled, the two routers will detect the NAT device during phase 1 negotiations, and will automatically encapsulate the ESP packets in UDP.
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RoninoAuthor Commented:
Unfortunately I don't see any options in the interface to enable NAT Traversal, in either the Motorola cable modem or the Westell DSL modem. I don't assume that the forwarding of UDP 4500 and UDP 1500 alone will take care of the problem?
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rr_haleCommented:
NAT-T is enabled on the routers terminating the VPN connection, not on the modems.
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RoninoAuthor Commented:
Got too complex already - but went back and found a simple solution.

You can call the cable company and ask for either
1. a dumb modem, with no routing  capabilities
2. that they turn off the routing and firewall features in the modem.

At that point, the domain name resolves correctly from inside or outside the network.

Thanks all!
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