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JCK_171200's avatar
JCK_171200
Icon for Nimbostratus rankNimbostratus
Aug 24, 2017

SMTP VIP Configuration

I've created an application service for load balancing inbound SMTP mail. The firewall sends inbound SMTP mail to a VIP on the F5. The F5 sends the mail on to one of our two CAS servers and it gets delivered. However, the address the CAS server receives the mail from is NOT the VIP, its the 'traffic-group-1' IP address. I would expect the 'sender' to be the VIP, no? Sorry for such a noob question. Thanks all!

 

These are BIGIP-2000 units running 11.4.1. iApp rule is

 

application delivery
BIG-IP
iRules

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  • Vijay_E's avatar
    Vijay_E
    Icon for Cirrus rankCirrus
    Aug 25, 2017

    When you say "traffic-group-1" IP address, is this the self-IP on the F5 ? If so, you may be using "snat automap" on the VS.

     

  • Kai_Wilke's avatar
    Kai_Wilke
    Icon for MVP rankMVP
    Aug 25, 2017

    Hi JCK,

    to overwrite the SNAT IP to the one used by your SMTP Virtual Server, you could simply attach the following iRule to your Virtual Server.

    when CLIENT_ACCEPTED {
    snat [IP::local_addr]
}

    ... alternatively you could also create a SNAT pool containing the IP of your Virtual Server and then use 

    snatpool "mypool"
    instead of 
    snat automap

    Cheers, Kai