Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Cisco NAT question

Posted on 2013-01-30
2
Medium Priority
?
400 Views
Last Modified: 2013-01-30
We have a Cisco ASA 5505 as firewall and trubble with NAT.

Firewall public IP: x.x.x.193.
Incoming traffic works fine, NAT of public ip x.x.x.194 to x.x.x.209 translates to private IP y.y.y.194 to y.y.y.209.

The problem is that outgoing traffic from local servers with IP y.y.y.194 (up to y.y.y.209) NAT through firewall via main IP x.x.x.193 not from x.x.x.194 (up to x.x.x.209).

Outgoing traffic from other local addresses in network y.y.y.0/24 routes correct via x.x.x.193.


Parts of config attached.
Cisco-ASA-conf.txt
0
Comment
Question by:AITP
[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
2 Comments
 
LVL 20

Accepted Solution

by:
rauenpc earned 2000 total points
ID: 38835327
A static NAT will normally take priority over an auto-NAT or Object nat. Although the line

nat (inside,outside) source dynamic any interface

Contains a dynamic source, it is still considered a static nat as it is not attached to a specific object.
If you do a "show nat" you will end up with at least two sections - "Manual NAT Policies (Section 1)" and "Auto NAT Policies (Section 2)"
These are processed in order, which means the static nat translating anything to the outside interface will happen before the object nat defined for servers to be translated to x.x.x.209.
You have two choices. If you change the static nat to specify its priority to be after-auto, you should be in good shape.

nat (inside,outside) after-auto source dynamic any interface

Or you can make an "any" object and do the dynamic nat there. Remember that nat is still done in order, so after making this object nat check the order of nats using "sh nat" to make sure the servers are before the all-encompassing any nat.

object network obj-any
subnet 0.0.0.0 0.0.0.0
 nat (inside,outside) dynamic interface




http://www.cisco.com/en/US/docs/security/asa/asa84/configuration/guide/nat_overview.html
0
 

Author Closing Comment

by:AITP
ID: 38835502
Worked perfect, did first suggested solution.
Thanx!
0

Featured Post

Get your Conversational Ransomware Defense e‑book

This e-book gives you an insight into the ransomware threat and reviews the fundamentals of top-notch ransomware preparedness and recovery. To help you protect yourself and your organization. The initial infection may be inevitable, so the best protection is to be fully prepared.

Question has a verified solution.

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

For months I had no idea how to 'discover' the IP address of the other end of a link (without asking someone who knows), and it drove me batty. Think about it. You can't use Cisco Discovery Protocol (CDP) because it's not implemented on the ASAs.…
Considering cloud tradeoffs and determining the right mix for your organization.
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…

715 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