how to enable smtp inside by name (telnet mail.xxxx.com 25) on ASA 5515-x?

[rechard_hk]

Dear all ,

how can we allow from inside telnet by name like ( telnet mail.xxx.com 25 ) , but if i'm at outside i can telnet mail.xxx.com 25 is working.

Best Regards,

Rechard

[rechard_hk]

Dear all ,

do you have any advice?

Best Regards,

Rechard

[Marius Gunnerud]

The reason you are not able to use mail.xxx.com from the inside is because it is most likely resolving to a public IP address.  To resolve this you can either adjust the FQDN to IP resolution in the DNS server so that it points to the private IP, or you can configure a NAT statement in the firewall that will translate requests for the public IP to the priave IP on port 25.

If the DNS server is located either on the Internet or on a different ASA interface you could use DNS rewrite so that all DNS requests for that server will be automatically translated to the private IP of the server.

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