I am wondering if the SMTP (port 25) is being blocked by default on the ASA 5510 Firewall. The reason I am asking is that when one of my exchange server tried to forward emails to the exchange inside the ASA 5510, the connections will always be dropped. I tried the packet tracer and it always say that the packet was dropped and the access rules that dropped it is the Implicit IP deny all rule.
I had performed a NAT on the 5510 for the exchange server and still the traffic does not comes in for Port 25 only. Specific rules had also been added to allow TCP/25 through but still the same problem. I wonder if there is an "inspection" on SMTP/25 which caused the problem? If not, how can I overcome this problem so that connections between the two exchange servers will talk to one another?
Attached please find the detailed config of the ASA. Please take note of the server SGPCRS02 which is the server in question. I can ping it from outside but still traffic to Exchange keeps reflecting connection drop.
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We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...