Port 3 of ASA 5510 firewall use to let outside traffic through to VPN router.

Posted on 2013-06-25
Last Modified: 2013-06-26
Dear Experts,

I need to let an ASA 5510 port let outside traffic pass though. I made its security 0 and gave it neither an external or internal IP address. That is the question. What else should I do to that port to it lets VPN traffic pass from another office to a cisco VPN router.

This is what it looks like:

interface Ethernet0/3
 nameif To_VPN_router
 security-level 0
 no ip address

Will this let outside traffic pass to the Cisco VPN Router?
Question by:marceloNYC
  • 4
  • 4
LVL 17

Expert Comment

ID: 39274691
Well the interface would need an IP. It is required that it has connectivity to the remote site, or remote users if it is remote access VPN.  Once you have established connectivity to the outside host/hosts and assuming that the VPN is configured correctly, things will start to work.

Author Comment

ID: 39274717
Yeah the VPN router is working right now using another ISP. We had change ISP and have no other interface available other than the one from the ASA. So you are saying I need to give this interface an external IP address and what else?

Should I use a switch instead?

I need to make the VPN router change its way to the internet over the ASA.
LVL 17

Expert Comment

ID: 39274740
If you could elaborate a bit more on what you are trying to do please.

Right now, yes you need an IP on the interface, also you would need to configure routing out that interface.  depending on your requirements you would either set up static routes pointing out that interface or you would set up a default route.  I would need to know more about your situation.  Will this be your primary ISP?  Will the ASA be the default gateway for your hosts? Will the existing VPN router still be used for something? will the existing ISP that the VPN router is using still be used?  Is the ASA only going to be used for VPN?

Author Comment

ID: 39275064
Okay, I need to make the VPN router access the internet with the new ISP. I have a ASA firewall connected to the AT&T Router. There is only one ISP now the other two and going to be discontinue.

I don't want the ASA to be the default gateway of the VPN router.

The ASA is not going to be use for site to site VPN .
The existent VPN router needs to change its public IP address and access to the web. Using the access the ASA has right now.  

So is it easier to use that 3rd port in the ASA firewall or should I put a switch in between the  ISP (AT&T router) with the ASA and VPN router.

remote vpn offices <--------------------------------------> ISP  AT&T router <---> ASA 5510

How do I get the VPN router to work with that order above. It is going to have its dedicated ISP line discontinue.
How to run any project with ease

Manage projects of all sizes how you want. Great for personal to-do lists, project milestones, team priorities and launch plans.
- Combine task lists, docs, spreadsheets, and chat in one
- View and edit from mobile/offline
- Cut down on emails

LVL 17

Expert Comment

ID: 39275973
I would give the AT&T router the new public IP if it doesnt have it allready, then assign an IP to the inside interface of the AT&T router (or is it configured as the DHCP server?), then ad an IP to the ASA outside interface so that it has connectivity with the router, then configure access rules, NAT (if needed), and routing so that the ASA can reach the remote clients (again if needed) and the internet.

Author Comment

ID: 39276075
No, The AT&T router is not managed by me. I have our Cisco VPN router and that ASA behind the AT&T router to the internet. I am thinking of using 3 switch ports in a switch with its own VLAN. I need to figure that one out. I am not liking using the third port for the ASA Anymore.
LVL 17

Accepted Solution

MAG03 earned 500 total points
ID: 39277156
In this case, yes a switch would be the easiest to get this working.

Author Closing Comment

ID: 39278195
Thank you for your time on this. It is good to have an experts opinion on the side :)

Featured Post

What Is Threat Intelligence?

Threat intelligence is often discussed, but rarely understood. Starting with a precise definition, along with clear business goals, is essential.

Join & Write a Comment

Suggested Solutions

There are many useful and sometimes not well documented or forgotten IOS or ASA/PIX commands. See IPE article here , there was also one on PacketU and on Cisco Tips & Tricks. Below are my favorites. I give also a few most often used for Cisco IPS an…
From Cisco ASA version 8.3, the Network Address Translation (NAT) configuration has been completely redesigned and it may be helpful to have the syntax configuration for both at a glance. You may as well want to read official Cisco published AS…
Internet Business Fax to Email Made Easy - With eFax Corporate (, you'll receive a dedicated online fax number, which is used the same way as a typical analog fax number. You'll receive secure faxes in your email, fr…
This video shows how to remove a single email address from the Outlook 2010 Auto Suggestion memory. NOTE: For Outlook 2016 and 2013 perform the exact same steps. Open a new email: Click the New email button in Outlook. Start typing the address: …

705 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

19 Experts available now in Live!

Get 1:1 Help Now