Question on pf in the context of opensmtpd

[bceverly]

Hi all,

I was thinking about my email setup that I have running right now where I am hosting my own mail server on a residential ISP (which blocks port 25 across the board. My solution was to stand up another server on a DigitalOcean VM that ran opensmtpd and relayed that mail to a high-numbered port on my server inside of the residential ISP network.

My question is this - did I massively over-engineer this? Could I have simply used a pf rule on the DigitalOcean VM to redirect port 25 traffic to my other host on a different port? Or would that not be a proper use of pf?

Thanks in advance. I'm really curious here if I could simplify my solution.

[jggimi]

Yes, PF can redirect TCP traffic with rdr-to. You haven't necessarily over-engineered, since you can use SMTP-specific filtering rules to accept/reject traffic, rather than only the layer 3 TCP/IP rules available with PF.

[bceverly]

Thanks @jggimi!