Blocked Port?

[Kevin Darcy]

Barry Margolin wrote:

> In article <93fm7s$bhk at pub3.rc.vix.com>,
> Eric Leslie <eric.leslie at metzgers.com> wrote:
> >
> >Hello:
> >This is a follow-up message to a message I sent to the list a few days ago
> >(subject: MX Records Change).
> >
> >Anyway, I did some more digging, and when I was connected to the new
> >provider, I used a port scanner to check ports 110, 80, and 25. Ports 110
> >and 80 came back active, but not port 25. This would explain the no
> >incomming email. When I go back to the old connection, I am able to connect
> >to all three ports.
> >
> >I called the provider and they said that it did not appear to be a problem
> >on their end. What I don't understand is why can I ping 2 of the 3 ports
> >when connected to them? I would think that if it was a problem on my end, I
> >wouldn't be able to connect to any of them AND I would have problems with
> >the other provider. And when I connect to the other provider (no config
> >changes occur) I am able to connect to all three ports.
> >
> >Anyone have any ideas for me to check if it is on my end? It is starting to
> >look like my only alternative is to switch providers. Thanks for any help
> >you can provide.
>
> Are media.metzgers.com and corp.metzgers.com really the same machine?  I
> can successfully connect to media's port 25, but when I try to connect to
> corp's port 25, I get "Connection refused".  This implies that both
> connections are up, but sendmail is only bound on the media interface's
> address.  I thought that sendmail always listened on all interfaces, but it
> seems like it's only listening on one of them.  Maybe sendmail started up
> before you enabled the corp interface, and it only binds to the interfaces
> that are up when it starts.  Try restarting sendmail on the machine and see
> whether you can connect.

Modern versions of sendmail allow you to specify a particular address or port or
even address family on which to listen. See the "DaemonPortOptions" option.


- Kevin