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Martin_Vlasko's avatar
Martin_Vlasko
Icon for Altocumulus rankAltocumulus
Jul 28, 2015

Preserve original source IP with SNAT for SMTP

Hi guys,   Reading through various posts here on devcentral I have a feeling I will not be able to achieve what I want but I rather ask again.   Our topology looks like: source -> firewall -> F...
application delivery
deployment
design
LTM
snat
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Kevin_Davies's avatar
Kevin_Davies
Icon for MVP rankMVP
May 09, 2018

haproxy's PROXY protocol https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt provides the solution to this problem.

 

This presents the clients real IP address as a line of data when establishing a connection to the SMTP server. The SMTP server has to support v1 of protocol and an iRule is written emulate the protocol on the backend connection.

 

This is the code for initiating a back-end connection to the SMTP server using this protocol

 

https://devcentral.f5.com/codeshare/proxy-protocol-initiator

 

This is not required but listed for reference. If you ever need to receive PROXY protocol connections then this handles that as well.

 

https://devcentral.f5.com/codeshare/proxy-protocol-receiver

 

  • NatDoyle's avatar
    NatDoyle
    Icon for Altostratus rankAltostratus
    Sep 21, 2020

    Gonna give this a go now thanks Kev