Port Forwarding Translating 587 to Smtp 25 ?

[Mesut Canbolat]

Hello  Dear Experts

1- Due to Isp -spam prevent policy our outlook clients can only send their emails
    via tcp port 587  as smtp port
2- Our mailserver does not support (Mailsite) listening on port  587  only listens at regular smtp port 25.

we are using a   little port forward program to  forward all 587 requests to our mail server's 25 port ..

*** Some times this little port forward program crashes due to high email-traffic

Here we have :
------------------------------------------------------------------------------------------------------------
Asa 5505 version : 7.2(4)
Asdm  Version : 5.2(4)

access-list outside_access_in extended permit tcp any host 92.92.92.18 eq smtp
access-list outside_access_in extended permit tcp any host 92.92.92.18 eq pop3
access-list outside_access_in extended permit tcp any host 92.92.92.18 eq 587

static (inside,outside) 92.92.92.18 192.168.25.75 netmask 255.255.255.255
access-group outside_access_in in interface outside

------------------------------------------------------------------------------------------------------------
How can we translate  all 587 requests from outside outlook  clients
to our 192.168.25.75 mail server as smtp-25 requests ..

Many Thanks in advance for your suuport and kind eforts

[Jennifer Halim]

Change the following static 1:1 translation from:

static (inside,outside) 92.92.92.18 192.168.25.75 netmask 255.255.255.255

To:

static (inside,outside) tcp 92.92.92.18 587 192.168.25.75 25 netmask 255.255.255.255

If IP address of 92.92.92.18 is also listening on different ports, then you can configure port forward for the other ports as well.

"clear xlate" after the above changes.

[Mesut Canbolat]

Hello Dear Halim

First of all  many thanks for your very  *prompt  answer + support ...

Please let me make sure before  I go ahead and apply :

----------------------------------Current Running Config ----------------------------------------

access-list outside_access_in  extended permit tcp any host 92.92.92.18 eq smtp
access-list outside_access_in extended permit tcp any host 92.92.92.18 eq pop3
access-list outside_access_in extended permit tcp any host 92.92.92.18 eq 587

access-list outside_access_in  extended permit tcp any host 92.92.92.18 eq www

static (inside,outside) 92.92.92.18 192.168.25.75 netmask 255.255.255.255
access-group outside_access_in in interface outside

------------------------------------------------------------------------------------------------------

Since this mail server services  as also  smtp 25 for email-relays-recieves for outside mail servers +

web server + pop3 and 587 server outlook clients :

(If IP address of 92.92.92.18 is also listening on different ports,

then  you can configure port forward for the other ports as well)

Is this config right to apply :

-----------------------------------Required Config to Go For Applying -------------------------

access-list outside_access_in  extended permit tcp any host 92.92.92.18 eq smtp
access-list outside_access_in extended permit tcp any host 92.92.92.18 eq pop3
access-list outside_access_in extended permit tcp any host 92.92.92.18 eq 587

access-list outside_access_in  extended permit tcp any host 92.92.92.18 eq www

no static (inside,outside) 92.92.92.18 192.168.25.75 netmask 255.255.255.255

static (inside,outside) tcp 92.92.92.18  587 192.168.25.75  25  netmask 255.255.255.255

static (inside,outside) tcp 92.92.92.18  25   192.168.25.75  25  netmask 255.255.255.255

static (inside,outside) tcp 92.92.92.18  80   192.168.25.75  80  netmask 255.255.255.255

static (inside,outside) tcp 92.92.92.18  110  192.168.25.75 110 netmask 255.255.255.255

access-group outside_access_in in interface outside

clear xlate

---------------------------------------------------------------------------------------------------------------

I will be very happy if you make me sure before I go for applying ...

Thanks ,

[Panos Kampanakis]

Everything is correct except for

static (inside,outside) tcp 92.92.92.18  587 192.168.25.75  25  netmask 255.255.255.255

static (inside,outside) tcp 92.92.92.18  25   192.168.25.75  25  netmask 255.255.255.255

You can't use both. You can't translate port 25 to both 587 and 25 on the outside. You might be able to do it with version 8.3 ONLY if your outside hosts that will be connect on port 25 or 587 are known.

I hope it helps.

PK

[Mesut Canbolat]

So, in my case  as a conclusion :

I will wait for Mailsite Mail Server  software-new version  supports to listen also port 587 as smtp reciever

Thanks a lot for your support .

All Best

[Panos Kampanakis · Accepted solution]

Probably that is your best bet.

Please mark this as answered if it is, for other users'' future benefit.

Rgs,

PK