Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

NAT Loopback - How To

Posted on 2014-02-09
10
Medium Priority
?
1,592 Views
Last Modified: 2014-02-21
I have a web server running on my LAN and have setup port forwarding etc. on my router so it can be accessed from the outside world using a valid URL: for example http://www.myexternaladdress.com:xxxx/mypage.html

Everything from outside works great, but I cannot access the server when on my LAN using the external address.

I know I can use the LAN address but I want to be able to use the one address from wherever I am, I think this is called NAT loopback but I'm no expert here.

How do I divert LAN traffic for the external web address to the internal web address?

I'm using a Comtrend AR5381u Router

Thanks
0
Comment
Question by:BrianFord
[X]
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
  • 5
  • 2
  • 2
  • +1
10 Comments
 
LVL 35

Expert Comment

by:Dan Craciun
ID: 39845814
That is called hairpin NAT, from what I know.

Does your router support CLI? It uses iptables?

From what consumer routers I've seen, if it does not support hairpin NAT out-of-the-box, your only chance is to modify it via CLI or a firmware update.

HTH,
Dan
0
 
LVL 35

Expert Comment

by:Dan Craciun
ID: 39845829
If you can access and modify iptables, here's a thread on how to create a rule for hairpin:
http://superuser.com/questions/663820/port-forwarding-from-inner-network-to-inner-network-hairpin-nat

Basically, you add a rule to your firewall to route internal traffic on port 80 to 192.168.1.2 (change with the IP of your server)
/ip firewall nat
add chain=dstnat dst-address-type=local protocol=tcp dst-port=80 \
  action=dst-nat to-address=192.168.1.2 to-port=80

Open in new window

and then add the hairpin:
/ip firewall nat
add chain=srcnat src-address=192.168.1.0/24 \
  dst-address=192.168.1.2 protocol=tcp dst-port=80 \
  out-interface=bridge-local action=masquerade

Open in new window


HTH,
Dan
0
 

Author Comment

by:BrianFord
ID: 39845866
not sure I can access the iptables, this is an isp provided router, sounds like I may to just use different URL's :-(
0
Understanding Web Applications

Without even knowing it, most of us are using web applications on a daily basis. Gmail and Yahoo email, Twitter, Facebook, and eBay are used by most of us daily—and they are web applications. We often confuse these web applications tools for websites.  So, what is the difference?

 
LVL 6

Expert Comment

by:Jelcin
ID: 39845896
You could also edit the hosts file in your windows. There you can just type that the external adress should be mapped to the internal...

http://www.rackspace.com/knowledge_center/article/how-do-i-modify-my-hosts-file
0
 

Author Comment

by:BrianFord
ID: 39845902
I thought about that but I'm building iOS app that needs to access a web service running on my web server so that's why I was trying to access using a single address and not  2
0
 
LVL 17

Expert Comment

by:pergr
ID: 39846719
It might be easier to configure your DNS server to give the private address when the request comes from the inside.
0
 

Author Comment

by:BrianFord
ID: 39876925
That's what I'd like to do but not sure how to do that, unfortunately not much in the manual on how to set that up,  I'm an ASUS RT-68U

Guess I'll be surfing Google again later today :)
0
 
LVL 17

Accepted Solution

by:
pergr earned 2000 total points
ID: 39877721
Perhaps you should run a dns server too on the same machine as the Web server.
0
 

Author Comment

by:BrianFord
ID: 39878504
I think I'm going  set that up, I'm not DNS expert, do have any pointers for setting up the hairpin on Windows Server 2003?
0
 

Author Closing Comment

by:BrianFord
ID: 39878516
Thanks for the advice, I setup a DNS server on the web server and after a quick Google search was able to implement the hairpin

Thank You
0

Featured Post

VIDEO: THE CONCERTO CLOUD FOR HEALTHCARE

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

Question has a verified solution.

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

When you try to share a printer , you may receive one of the following error messages. Error message when you use the Add Printer Wizard to share a printer: Windows could not share your printer. Operation could not be completed (Error 0x000006…
This article is in regards to the Cisco QSFP-4SFP10G-CU1M cables, which are designed to uplink/downlink 40GB ports to 10GB SFP ports. I recently experienced this and found very little configuration documentation on how these are supposed to be confi…
If you're a developer or IT admin, you’re probably tasked with managing multiple websites, servers, applications, and levels of security on a daily basis. While this can be extremely time consuming, it can also be frustrating when systems aren't wor…
Monitoring a network: how to monitor network services and why? Michael Kulchisky, MCSE, MCSA, MCP, VTSP, VSP, CCSP outlines the philosophy behind service monitoring and why a handshake validation is critical in network monitoring. Software utilized …
Suggested Courses

604 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