Solved

Cisco Router with Radius authentication for VPN with ASA in the middle

Posted on 2014-02-18
1
53 Views
Last Modified: 2015-12-10
Hello,

I have an interesting situation which I have not seen before. Maybe someone can help. We have a Cisco 2921 with IOS 15.1 connected to the internet on Gi0/0. The 2921 is doing NAT as that is the border router.

Gi0/1 of the 2921 is connected to a Cisco ASA 5505 on Eth0/0 (outside). Eth0/1 of ASA is connected to a Layer 3 switch (3750).

This is a very common deployment scenario. Now the problem:

We are using a radius server behind the ASA on the inside interface to authenticate our VPN users. VPN termination is NOT done on the ASA instead on the 2921. ASA is running in routed mode.

The interesting thing I am noticing is when Windows Server 2008 receives an authentication request from the router, the source address in the packet capture is the ASA's inside address. So obviously the server responds back to that address with success however that request never reaches the router. The 2921 keeps waiting for a response from Radius and then times out.

However if i ping from the 2921 to this Radius server and check the packet capture using Wireshark, the source ip on the packet is correct (2921's gi0/1). Since the ASA is not doing NAT (no nat-control) looks like somewhere on the ASA there is a problem.

We don't have any outbound ACL's on the ASA and for testing I opened up everything using permit ip any any and still the same result. Since ping's can reach from the 2921 to the radius server, i did rule out ACL.

Thoughts?
0
Comment
Question by:bbwonders
1 Comment
 
LVL 12

Accepted Solution

by:
Henk van Achterberg earned 500 total points
ID: 39872519
This is indeed weird behaviour. When you run the packet capture on the ASA itself do you see if the packets are sent back?

Can you post a sanitized config of your ASA?

http://www.cisco.com/c/en/us/support/docs/security/asa-5500-x-series-next-generation-firewalls/110117-asa-capture-asdm-config.html

https://supportforums.cisco.com/docs/DOC-17814
0

Featured Post

Microsoft Certification Exam 74-409

Veeam® is happy to provide the Microsoft community with a study guide prepared by MVP and MCT, Orin Thomas. This guide will take you through each of the exam objectives, helping you to prepare for and pass the examination.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article assumes you have at least one Cisco ASA or PIX configured with working internet and a non-dynamic, public, address on the outside interface. If you need instructions on how to enable your device for internet, or basic configuration info…
I recently updated from an old PIX platform to the new ASA platform.  While upgrading, I was tremendously confused about how the VPN and AnyConnect licensing works.  It turns out that the ASA has 3 different VPN licensing schemes. "site-to-site" …
Both in life and business – not all partnerships are created equal. As the demand for cloud services increases, so do the number of self-proclaimed cloud partners. Asking the right questions up front in the partnership, will enable both parties …
As a trusted technology advisor to your customers you are likely getting the daily question of, ‘should I put this in the cloud?’ As customer demands for cloud services increases, companies will see a shift from traditional buying patterns to new…

896 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

13 Experts available now in Live!

Get 1:1 Help Now