Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people, just like you, are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
Solved

How do I permit passthru on a Cisco ASA 5505

Posted on 2010-09-18
8
366 Views
Last Modified: 2012-05-10
Hi, I have a ciscoe asa 5505 firewall.  I have it all configured so that everyone works great, except I can have a server communicate with itself using any outside IP.  I am curious to know how I can do this.  Any option that will work is excellent.  The server is nothing that needs to be secured or firewalled really, the basics of any protection it would need can be handled via software firewall, if an issues arrises.  Also I have more than one external ip, in fact I have one for machine on the inside, so giving that particular machine an static assigned external ip is not an issue.  I basically just need to be able to set the external ip with a listening port so that people from outside can access it, but at the same time I need for that machine itself to be able to verify that the service is readable.  So it needs to be able to communicate with itself on the outside IP address.  Screwy program I know.  Any help is greatly appreciated.
0
Comment
Question by:danvilleadmin
  • 3
  • 3
  • 2
8 Comments
 
LVL 24

Expert Comment

by:rfc1180
ID: 33707947
With DNS rewrite or NAT hairpinning

Are you connecting to public IP by DNS hostname?  If so, is the name resolved externally or via internal DNS servers?  If external, you can use DNS doctoring to rewrite the DNS response to the internal IP address.  This is a better option if possible versus hairpinning as the client to server traffic stays on the LAN and the ASA never sees it.

http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a00807968d1.shtml

Billy
0
 
LVL 17

Accepted Solution

by:
Kvistofta earned 500 total points
ID: 33707952
One of the basic rules/limitations of ASA is: An inside host cannot communicate with another inside host by calling an outside ip. It simply doesnt work that way. Your question applies to this, the fact that the inside host is the same as the called host doesnt change anything.

What you can (or cant, depending on your application) is to fool the host with DNS. Either an internal DNS that resovles a domain name to an internal ip or an external DNS-server and doa dns-doctoring in the static-command.

If the application really requires to do this I would recommend putting the server behind an asa in transparent mode. By doing that you can still protect it but you can give the server an public ip so that it can "call" its own public IP. By doing this you dont do any address translation in your transparent firewall.

Anyhow, you need to do a workaround in some way or other, because exactly what you requests cannot be done in ASA. Sorry.

/Kvistofta
0
 

Author Comment

by:danvilleadmin
ID: 33708024
Kvisofta, the idea of putting the server bhind an asa in transparent mode is perfectly fine with me.  Can you by any chance give any input on how this can be done, sorry, my experience with Cisco has never been with an asa until now.

rfc1180, no its by ip not by dns.
0
Windows Server 2016: All you need to know

Learn about Hyper-V features that increase functionality and usability of Microsoft Windows Server 2016. Also, throughout this eBook, you’ll find some basic PowerShell examples that will help you leverage the scripts in your environments!

 
LVL 24

Expert Comment

by:rfc1180
ID: 33708037
>rfc1180, no its by ip not by dns.

Alternative Solution: Hairpinning
http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a00807968d1.shtml#solution2

Billy
0
 
LVL 17

Expert Comment

by:Kvistofta
ID: 33708137
Have a look at this documentation for explaining ASA in transparent mode:

http://www.cisco.com/en/US/products/hw/vpndevc/ps2030/products_configuration_example09186a008089f467.shtml

Basically, you put it "invisible" with 2 interfaces on the same network segment and do port-filtering in the firewall for all traffic passing the "stealth mode" firewall.

/Kvistofta
0
 

Author Comment

by:danvilleadmin
ID: 33708360
Ok I'm reading thru the page on ASA in Transparent mode...it appears this is only going to apply to the whole ASA and not just the one server is that correct???  I really need to have the majority of the network behind the ASA as is now, but the one server on the outside.
0
 
LVL 17

Expert Comment

by:Kvistofta
ID: 33708513
Yes, that is correct.

/Kvistofta
0
 

Author Comment

by:danvilleadmin
ID: 33709051
Any suggestion that would allow me to only affect one pc
0

Featured Post

PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

Question has a verified solution.

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

Use of TCL script on Cisco devices:  - create file and merge it with running configuration to apply configuration changes
Concerto Cloud Services, a provider of fully managed private, public and hybrid cloud solutions, announced today it was named to the 20 Coolest Cloud Infrastructure Vendors Of The 2017 Cloud  (http://www.concertocloud.com/about/in-the-news/2017/02/0…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
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…

791 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