* dman ([EMAIL PROTECTED]) [020419 09:10]:
> On Fri, Apr 19, 2002 at 11:22:56AM -0400, Shawn McMahon wrote:
> | begin  Noah Meyerhans quotation:
> | > HA!  That's the most rediculous thing I've ever heard on this list.
> | 
> | "ridiculous".

"pedantic".

> | 
> | > The
> | > only thing a firewall is good for is to provide you with a false sense
> | > of security.
> | 
> | A firewall is a useful tool for securing a network.  If you don't know
> | enough about security to know that, you shouldn't be pontificating on
> | the subject in a public list.  Like any other tool, it is neither
> | necessary nor sufficient in and of itself.

Well said.

> | 
> | > If you want to be able to run services like web or mail
> | > servers, you by definition must start punching holes in your firewall.
> | 
> | And, of course, opening a single hole in a firewall makes it completely
> | useless.  NOT.  Go away, troll.
> 
> Noah isn't a troll.  He absolutely right here -- if you run a mail
> server, no firewall will prevent you from becoming an open relay.
> The only firewall that will prevent your mail server from being an
> open relay is one which disconnects the mail server from the rest of
> the world (and prevents you from getting any mail at all).  If you are
> to run a mail server you have to open TCP port 25.  Once you've done
> that, your firewall doesn't help you on port 25 and you must then look
> to other means for securing that part of your system/network.
> 
> Noah (and I) didn't say a firewall was useless, just that discussing
> firewalls when the problem is a (potential) mail relay is wholly
> pointless.

Well, there may be other issues on the table here. Will's original
question was "can I tell if I've been hacked?" His exim setup could be
sound, but it's definitely feasible that a rootkit could install a mail
relay listening on another port and sending out a ton of spam
unbeknownst to ps and top. Are your hub lights blinking, Will?

If that rootkit was installed by somebody exploiting a samba which
should have been blocked from The Outside, this could potentially have
been prevented if a packet filter was installed to allow incoming
connections only to tcp/25.

Also, I'm pretty sure Noah did say the firewall was useless - that the
only thing it's good for is a false sense of security. 'Troll' may be a
bit strong, but then, so was his remark about the usefulness of
firewalls!

-- 
Currently seeking opportunities in the SF Bay Area
Please see http://www.doorstop.net/resume.shtml

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