Let's say that I want to open and redirect all the SMTP traffic that reach my ADSL router to my internal mail server (192.168.1.34)
The ACL that it seems to work is
permit tcp any gt 1023 host 192.168.1.34 eq smtp
This ACL will be aaplied to the external interface (in) of the ADSL router.
Could any one explain why "permit tcp any host 192.168.1.34 eq smtp" might not work.
If smtp uses port 25 why we have to enable any port greater than 1023?