Wietse Venema:
> J Doe:
> > Hello,
> >
> > I noticed something interesting in my logs today. I am running Postfix
> > 3.3.1:
> >
> > Aug 24 21:09:25 server postfix/submission/smtpd[10256]: connect from
> > unknown[unknown]:unknown
> > Aug 24 21:09:25 server postfix/submission/smtpd[10256]: lost connection
> > after CONNECT from unknown[unknown]:unknown
> > Aug 24 21:09:25 server postfix/submission/smtpd[10256]: disconnect from
> > unknown[unknown]:unknown commands=0/0
> >
> > It is clear that this was a bad connection, but under what
> > circumstances does Postfix consider a remote connection?s address
> > as ?unknown? ? Wouldn?t Postfix always know the remote IPv4/IPv6
> > address because when a client connects to the server the address
> > is passed from the OS to Postfix ?
>
> "unknown" clients are defined in
> http://www.postfix.org/postconf.5.html#reject_unknown_client_hostname
>
> reject_unknown_client_hostname (with Postfix < 2.3: reject_unknown_client)
>
> Reject the request when 1) the client IP address->name mapping
> fails, or 2) the name->address mapping fails, or 3) the
> name->address mapping does not match the client IP address.
The "unknown" address means that the connection was already closed
when Postfix asked the OS for the client IP address.
Wietse
