Initiate a VPN from a cisco router on the local LAN behind ASA?

[Mike Thomas]

We currently have an ASA with site to site VPN and anyconnect VPN being utilized. We received a third party  cisco router which will  be used to initiate their own site to site VPN from inside our local LAN to their LAN through our ASA.

1. Would NAT Traversal be required on our ASA? 5540(config)#crypto isakmp nat-traversal

2. Would the ports listed below interfere with ports for site to site VPN and anyconnect VPN?

SSH

- allow access from xxxxx on TCP Port 22

ICMP

               - allow access from xxxxx - protocol 1

ISAKMP

              - allow access to xxxxx on UDP Port 500, also add UDP 4500 for NAT-T

ESP

               - allow access to/from xxxxx - protocol 50

Certificate port:

               - allow access to/from xxxxx  on TCP port 8080

NTP port:

               - allow access to/from xxxxx on UDP port 123

[Javier Portuguez · Accepted solution]

Hi Michael,

1-

NAT-T is only required if one of the sites is behind NAT.

NAT-T lets IPsec peers establish a connection through a NAT device. It does this by encapsulating IPsec traffic in UDP datagrams, using port 4500, which provides NAT devices with port information. NAT-T auto-detects any NAT devices and only encapsulates IPsec traffic when necessary. This feature is disabled by default.

http://www.cisco.com/en/US/docs/security/asa/asa84/configuration/guide/vpn_ike.html#wp1120836

2-

ISAKMP

              - allow access to xxxxx on UDP Port 500, also add UDP 4500 for NAT-T

ESP

               - allow access to/from xxxxx - protocol 50

The ports above are the ones used for IPsec VPN, AnyConnect SSL does not use them.

Let me know.

Thanks.

Portu.

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Message was edited by: Javier Portuguez