04-15-2009 02:28 AM - edited 03-11-2019 08:18 AM
Hello,
We have 2 email servers with 2 Nics. One has a public IP (e.g 10.10.10.10)NAT'ed to it's private IP for inbound email, so inbound email is fine. Now our ISP only accept smtp traffic from 10.10.10.10 and the issue I have is the server with the NAT can send emails to them, but the server that doesn't have the NAT servers it's smtp traffic outbound via the ASA's default gateway and gets refused.
Is it possible to route this server with no NAT to route outbound via the 10.10.10.10 so both servers go outbound via this and not the ASA's default gateway?
Thanks
04-15-2009 02:45 AM
Why do you not write a policy based nat rule so both servers use the same external NAT IP?
04-15-2009 02:50 AM
Hmm I've never tried that before, plus I only use the ASDM, but do have access tot he CLI and have basic experience with this.
How would I do this then?
Say 192.168.28.1 and 192.168.28.2 wanted to go outbound via 10.10.10.10 (public IP)?
04-15-2009 03:01 AM
I do not use the ASDM, not even sure if it is capable to configure something like this in the ASDM, via cli
global (outside) 99 10.10.10.10
access-list email-servers extended permit tcp host 192.168.28.1 any eq smtp
access-list email-servers extended permit tcp host 192.168.28.2 any eq smtp
nat (inside) 99 access-list email-servers
Basically the above instructs the ASA to NAT servers 192.168.28.1 & .2 when they try an access anything out on the internet using smtp and NAT them to external IP 10.10.10.10
HTH>
04-15-2009 04:19 AM
Thanks,
As one of the email servers has the public IP (10.10.10.10) assigned to it via NAT, can I just do the above method to just the server that needs it?
Also, are there any useful commands that will show me that it is using this new public IP?
04-15-2009 04:21 AM
Sorry - I am no confused, if you are performing a specific static NAT - you WILL have to change it from a 1:1 to a 1:Many
You cannot just add an internal server, you will have to configure either a static 1:Many NAT based on an access-list or a policy based NAT.
HTH>
04-15-2009 04:55 AM
OK, wil I have to first remove the current NAT?
04-15-2009 05:02 AM
Yes you will have to remove the current NAT statements, and clear the NAT xlate table.
04-15-2009 06:42 AM
Sorry to confuse:
Could I:
Get the 2 email servers send outbound as public IP 10.10.10.10 on smtp
But only nat 10.10.10.10 inbound to one of the email servers on smtp?
04-15-2009 07:06 AM
No - the ASA will send return traffic back to either server.
So if you have an environment where only 1 email server is receving/delivering email - but both servers are sending email out to the internet, you need to look at your email environment.
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