From: "Hansa" <mythtv@logic-q.nl>
To: 'Andrew Beverley' <andy@andybev.com>
Cc: netfilter@vger.kernel.org
Subject: RE: Is the current firewall model static?
Date: Wed, 21 Dec 2011 10:18:13 +0100 [thread overview]
Message-ID: <002201ccbfc1$7743d7f0$65cb87d0$@nl> (raw)
In-Reply-To: <1324375868.21032.1.camel@steve-pc>
From: Andrew Beverley [mailto:andy@andybev.com]
Sent: dinsdag 20 december 2011 11:11
> On Tue, 2011-12-20 at 10:25 +0100, Hansa wrote:
> > Hi there,
> >
> > Fedora is running a project called firewalld. Firewalld manages the
> firewall
> > dynamically via D-BUS
> > (http://fedoraproject.org/wiki/FirewallD/#Why_A_Firewall_Daemon).
> They say:
> > "the current firewall model is static and **every** change requires a
> > complete firewall restart. This includes also to unload the firewall
> > netfilter kernel modules and to load the modules that are needed for
> the new
> > configuration."
> >
> > I would be very surprised if their claim is true. Because that would
> break
> > statefull connections when changing the rules. I'm not familiar with
> the
> > code so I can't comment on that. Hence my question. Is the current
> firewall
> > model static?
>
> I think that what they mean is that the current *Fedora* firewall model
> is static. It looks like firewalld still uses iptables, but is slightly
> more intelligent as to how it processes changes to rules and so on.
I wasn't aware the firewall model is implemented differently across different Linux flavors. I thought netfilter implements a packet filtering framework into the Linux kernel. Shouldn't it work the work the same on every Linux flavor? I did the following test.
Ssh on port 22 into a Linux box with following filter rules
# iptables -L -n --line-numbers
Chain INPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
2 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
3 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
4 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Remove line 3, so new ssh connections are rejected. The current ssh session however should be working because of rule number 1.
# iptables -D INPUT 3
# echo "yup it does"
yup it does
Seems pretty much dynamic to me :)
Am I missing something?
-Hansa
next prev parent reply other threads:[~2011-12-21 9:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-20 9:25 Is the current firewall model static? Hansa
2011-12-20 10:11 ` Andrew Beverley
2011-12-21 9:18 ` Hansa [this message]
2011-12-21 9:27 ` Andrew Beverley
2011-12-21 10:16 ` Hansa
2011-12-21 10:22 ` Andrew Beverley
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