topic Re: NAT different for outgoing mail in Network Security

NAT different for outgoing mail

totallygeek — Mon, 11 Mar 2019 12:25:13 GMT

I currently am NAT'ing all RFC-1918 addresses out the firewall to the Internet. However, I want outgoing mail to appear to originate from a different IP.

So, 10.0.0.1 NATs out as 1.1.1.50

10.0.0.2 (a mail server) should browse Internet appearing to be 1.1.1.50

10.0.0.2 should connect to remote tcp/25 appearing to be from 1.1.1.75

Any way to accomplish this?

Re: NAT different for outgoing mail

i-kendall — Tue, 01 Apr 2008 10:38:33 GMT

I am sure it can be done. If you create an access list for the e-mail traffic, and a separate one for other traffic, and apply each to a different nat statement. The syntax for the nat is a bit different for a router or PIX/ASA,you don't say which you have, but is broadly the same technique.

Hope this helps.

Regards,

Iain

Re: NAT different for outgoing mail

totallygeek — Tue, 01 Apr 2008 14:35:28 GMT

Sorry, the system is an ASA 5500.

Re: NAT different for outgoing mail

abinjola — Tue, 01 Apr 2008 20:04:25 GMT

nat (inside) 1 10.0.0.1

global (outside) 1 1.1.50

access-l abc permit ip host 10.0.0.2 any

nat (inside) 10 access-l abc

global (outside) 10 1.1.1.50

access-l def permit tcp host 10.0.0.2 any eq 25

nat (inside) 20 access-l def

global (outside) 20 1.1.1.75