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Jeff_42220's avatar
Jeff_42220
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Apr 01, 2009

Anyway to "redirect" SMTP traffic?

I am looking at putting our Outlook Web Access (OWA) servers behind our LTM (running 9.3.0 code) for better load balancing. These servers, as they stand currently, also handle SMTP functions so different devices/servers send mail to them. When these go behind the LTM, we want to take the SMTP services off of these boxes, and have these boxes simply handle OWA. Users currently go to mail.ourdomain.com for OWA and many applications/devices also send SMTP to mail.ourdomain.com. We have a separate server, smtp.ourdomain.com, that the applications/servers should be sending mail to, but it's going to take a long time for our coders to update all their references to mail.ourdomain.com and change it to smtp.ourdomain.com.

 

 

So, that brings me to my question, which is: Is there a way I can have the F5 listen for incoming SMTP connections targeting a virtual server on port 25 (mail.ourdomain.com), and somehow redirect or forward those SMTP connections to smtp.ourdomain.com? The SMTP server is NOT behind the F5 currently so I'm looking for this redirect/forward to send the SMTP connections to a server that is not behind the F5.

 

 

Thanks!

 

 

Jeff
application delivery
dev
devops
iRules
  • The_Bhattman's avatar
    The_Bhattman
    Icon for Nimbostratus rankNimbostratus
    Apr 01, 2009
    You can do this w/o creating an irule.

     

     

    As long as the F5 itself can reach the SMTP server on the network, then you could create a VS on port 25, create a pool with the SMTP server (you can do this w/o the SMTP server behind the F5) and then apply the autosnat on the VIP itself.

     

     

    I.E.

     

    You have a VIP 192.168.12.90:80 and 192.168.12.90:443 for OWA. For SNMP you can do 192.168.12.90:25.

     

     

    What happens is that when a server sends SMTP to the virtual address it will forward it to the SMTP server using the LTM's routing table. The autosnat basically ensures the return traffic cross back through the F5 to complete the communication path. Without autosnat the Client who send the SNMP would drop the response packet because it expected it from the virtual address not the SMTP server address itself/.

     

     

    I hope this helps

     

     

    CB