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Date:      Tue, 8 May 2001 22:19:48 -0500
From:      Mike Meyer <mwm@mired.org>
To:        Dru <genisis@istar.ca>
Cc:        questions@freebsd.org
Subject:   Re: limit telnet access
Message-ID:  <15096.46932.622324.43579@guru.mired.org>
In-Reply-To: <31588347@toto.iv>

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Dru <genisis@istar.ca> types:
> Very good question, now you have me curious. Is it possible to tell a
> daemon to only listen on specified interfaces, or do we instead use
> firewall rules and tcpwrappers to ensure the daemon only sees the requests
> we actually want it to respond to? I suspect the latter, but would be
> interested in any URLs that would explain the semantics of how this works.

Of course it's possible to tell a daemon to only on listen specific
interfaces. Some daemons just don't listen, though :-).

I don't know of any way to specify *interfaces* except with firewall
rules. Not even tcp wrappers can do that. If you're willing to use IP
addresses instead - like the ones that interface is configured for -
then it's possible for a daemon to listen for connections only on a
specific IP address, instead of on all of them. If you're running a
daemon that has such an option, you can just use it.

The standard telnetd supplied with FreeBSD doesn't listen to ports -
it's started from inetd. Inetd can be configured to bind to a specific
address, so you could have one inetd that runs daemons for internal
ports, and another that runs daemons for external ports - or maybe you
don't want that second one. See the inetd man page for more
information.

	<mike
--
Mike Meyer <mwm@mired.org>			http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.

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