Forum Discussion

Altocumulus

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...

MVP

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