[BlueOnyx:01185] Re: Problems with nat

[Chris Gebhardt - VIRTBIZ Internet]

Thomas Andreassen wrote:
> This is not a general blueonyx problem I think, but an sendmail issue I have tried to solve, but is stuck.
> 
> I have an inbound nat to port 25 on my blueonyx, from my external IP. This is working great. But, it acts as an open relay. When my sendmail get the smtp mail, it think that all mail is sent from internal net, and relays it. The /var/log/maillog say that bla bla bla from 192.168.x.1 and relay the mail. 
> 
> The postmaster account is also spammed with reject mail when I put som firewall rules on my router. (mikrotik)
> 
> I have tried both netmap and dst-nat rules to try to get the server to understand that the sender ip, is not my nat box, but the other SMTP servers IP address. (qmail get this without problem with both netmap and dst-nat)
> 
> The issue was not an issue when I used qmail, who do not accts as default relay. 
> 
> I don't know if there is a solution to this, but all hint are welcome.
> 
> Sorry if this is the wrong mailinglist to ask. (but I had no problems using clarkconnect or deeproot who use qmail, and I think this may be a problem for other ppl too).

I'm guessing that you're really using port-forwarding/redirection?

Do you have your allowed relay set for your gateway's IP address?  If 
so, then the BX box is going to just relay blindly from that IP (since 
that's what it is being told to do).   I would instead  pull your 
gateway (the router) IP address out of there.   Then the BX box should 
only relay for the domains it hosts.

Or perhaps I'm misunderstanding your setup.

When you say your postmaster account is "spammed", do you really mean 
that you're getting a bunch of rejection messages (NDRs) because the 
messages won't go out?  In that case, make sure you check your firewall 
rules to be sure that you're not blocking something you shouldn't be.

-- 
Chris Gebhardt
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