From owner-freebsd-questions@FreeBSD.ORG Tue Aug 25 22:11:37 2009 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 9535A106568F for ; Tue, 25 Aug 2009 22:11:37 +0000 (UTC) (envelope-from amvandemore@gmail.com) Received: from mail-gx0-f227.google.com (mail-gx0-f227.google.com [209.85.217.227]) by mx1.freebsd.org (Postfix) with ESMTP id 426A68FC23 for ; Tue, 25 Aug 2009 22:11:37 +0000 (UTC) Received: by gxk27 with SMTP id 27so4451216gxk.12 for ; Tue, 25 Aug 2009 15:11:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:cc:content-type; bh=P/hhp7SBatC7HaK/UMMAY5FUYfy7nwZOMekjZl0lOlU=; b=WEHo9uz3MUAdhLMAihkZq/x2KwlEdna73mEkD56xNBZqMUMEvFmOr2By/zgoqIPiwR sO+4gxY8K24CikdLPquyCIOIMKNzwErcgPg/MPvB5gXIjihlxeUU/pEq8oZIYzsrrHmh TdbLkaP9hGhSv5/3qr4KWce9u5Ljn4p5pfuNc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=XCu1ZqZKExn3WFaonSXGzawNJhTtWE4QuneimXeQYdtMy7Ou5MVy7KALeT9J7POIEy Z9RIhLn00zxl8girDSAjKux2gVzQ6kMBNrNuNyfAa25pHyARqQ1ivm5n8Ofcu9Lka26v 3GVZyLaMNGf+b545bBkCX3JIapXWw8Y13i4wc= MIME-Version: 1.0 Received: by 10.150.110.1 with SMTP id i1mr7239843ybc.63.1251238295057; Tue, 25 Aug 2009 15:11:35 -0700 (PDT) In-Reply-To: <20090825154358.7c792d3a.wmoran@potentialtech.com> References: <4A924601.3000507@lim.nl> <25132123.post@talk.nabble.com> <20090825082604.41cad357.wmoran@potentialtech.com> <25134277.post@talk.nabble.com> <20090825120504.93a7c51d.wmoran@potentialtech.com> <6201873e0908250921w46000c2by78893a1c5b581e78@mail.gmail.com> <20090825130616.20ab0049.wmoran@potentialtech.com> <6201873e0908251237n5c819d9ag36f867b5e68e258c@mail.gmail.com> <20090825154358.7c792d3a.wmoran@potentialtech.com> Date: Tue, 25 Aug 2009 17:11:34 -0500 Message-ID: <6201873e0908251511q643f3662nc73f264cbfcfe645@mail.gmail.com> From: Adam Vande More To: Bill Moran Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: Paul Schmehl , freebsd-questions@freebsd.org, Colin Brace Subject: Re: what www perl script is running? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 25 Aug 2009 22:11:37 -0000 On Tue, Aug 25, 2009 at 2:43 PM, Bill Moran wrote: > In response to Adam Vande More : > > > On Tue, Aug 25, 2009 at 12:06 PM, Bill Moran >wrote: > > > > > In response to Adam Vande More : > > > > > > > On Tue, Aug 25, 2009 at 11:05 AM, Bill Moran < > wmoran@potentialtech.com > > > >wrote: > > > > > > > > > In response to Paul Schmehl : > > > > > > > > > > > --On Tuesday, August 25, 2009 08:30:17 -0500 Colin Brace < > cb@lim.nl> > > > > > wrote: > > > > > > > > > > > > > Bill Moran wrote: > > > > > > >> > > > > > > >> You can add an ipfw rule to prevent the script from calling > home, > > > > > which > > > > > > >> will effectively render it neutered until you can track down > and > > > > > actually > > > > > > >> _fix_ the problem. > > > > > > > > > > > > > > Mike Bristow above wrote: "The script is talking to > 94.102.51.57 on > > > > > port > > > > > > > 7000". OK, so I how do I know what port the script is using for > > > > > outgoing > > > > > > > traffic on MY box? 7000 is the remote host port, right? > > > > > > > > > > > > > > FWIW, here are my core PF lines: > > > > > > > > > > > > > > pass out quick on $ext_if proto 41 > > > > > > > pass out quick on gif0 inet6 > > > > > > > pass in quick on gif0 inet6 proto icmp6 > > > > > > > block in log > > > > > > > > > > > > > > That is to say: nothing is allowed in unless explicitly allowed > > > > > > > Everything allowed out. > > > > > > > (plus some ipv6 stuff I was testing with a tunnel) > > > > > > > > > > > > > > > > > > > The problem with blocking outbound ports is that it breaks things > in > > > odd > > > > > ways. > > > > > > For example, your mail server listens on port 25 (and possibly > 465 as > > > > > well) but > > > > > > it communicates with connecting clients on whatever ethereal port > the > > > > > client > > > > > > decided to use. If the port the client selects happens to be in > a > > > range > > > > > that > > > > > > you are blocking, communication will be impossible and the client > > > will > > > > > report > > > > > > that your mail server is non-responsive. > > > > > > > > > > You're doing it wrong. Block on the destination port _only_ and > you > > > don't > > > > > care about the ephemeral ports. > > > > > > > > What ports would you block then when you're trying to run a > webserver? > > > > > > My point (which is presented in examples below) is that you block > > > everything > > > and only allow what is needed (usually only dns and ntp, possibly smtp > if > > > the web server needs to send mail) > > > > > > That single statement above was directed specifically at the comment > about > > > it being impossible to predict (and thus block) ephemeral source ports. > > > He's > > > right about that, and that's why filtering on the destination port is > the > > > more common practice. > > > > > > Of course, that caused me to create an email that seems to contradict > > > itself, if you don't notice that it's two answers to two different > > > comments. > > > > My point was that it's unfeasible to block by destination point. You can > > only block by destination port if it's a known quantity, and the > destination > > port is ephemeral in the question I posed(which what the OP had an issue > > with). > > Please read the entire email before you respond. My last example below > demonstrates how to do what you call "unfeasible". > > > > > > > It's much easier to block outgoing ports for services you *don't* > > > want to > > > > > > offer, but, if the service isn't running anyway, blocking the > port is > > > > > > non-productive. > > > > > > > > > > You're obviously misunderstanding me completely. Your not blocking > > > > > incoming > > > > > connections, your preventing outgoing ones, which means there _is_ > no > > > > > service running on your local machine. > > > > > > > > > > For example, a server that is _only_ web (with SSH for admin) could > > > have > > > > > a ruleset like: > > > > > > > > > > pass in quick on $ext_if proto tcp from any to me port > {25,587,465,22} > > > keep > > > > > state > > > > > pass out quick on $ext_if proto tcp from me to any port {25} keep > state > > > > > pass out quick on $ext_if proto upd from me to any port {53,123} > keep > > > state > > > > > block all > > > > > > > > > > (note that's only an example, there may be some fine points I'm > > > missing) > > > > > > > > > > One thing that had not yet been mentioned when I posted my earlier > > > comment, > > > > > is that this system is a combination firewall/web server. That > makes > > > the > > > > > rules more complicated, but the setup is still possible: > > > > > > > > > > pass in quick on $ext_if proto tcp from any to me port {80} keep > state > > > > > pass out quick on $ext_if proto upd from me to any port {53,123} > keep > > > state > > > > > pass out quick on $ext_if from $internal_network to any all keep > state > > > > > block all > > > > > > > > > > Which allows limited outgoing traffic originating from the box > itself, > > > > > but allows unlimited outgoing traffic from systems on > > > $internal_network. > > > > > > > > > > I've done this with great success. In fact, I had a fun time where > a > > > > > client in question was infected with viruses out the wazoo, but the > > > > > viruses never spread off their local network because I only allowed > > > > > SMTP traffic to their SMTP relay, which required SMTP auth (thus > the > > > > > viruses couldn't send mail) > > > > > > > > > > > > > > > > > > > > > > -- > > > > Adam Vande More > > > > _______________________________________________ > > > > freebsd-questions@freebsd.org mailing list > > > > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > > > > To unsubscribe, send any mail to " > > > freebsd-questions-unsubscribe@freebsd.org" > > > > > > > > > -- > > > Bill Moran > > > http://www.potentialtech.com > > > http://people.collaborativefusion.com/~wmoran/ > > > > > > > > > > > > -- > > Adam Vande More > > You said block by destination port. What you presented is not this, although it gives give a functional environment of it. Sorry for the pedantic pursuit here, but IMO terminology is important here. -- Adam Vande More