Disabling firewalld on AWS?

[Sam Kottler]

----- Original Message -----
> From: "Daniel J Walsh" <dwalsh at redhat.com>
> To: "Fedora Cloud SIG" <cloud at lists.fedoraproject.org>
> Cc: "Sam Kottler" <skottler at redhat.com>
> Sent: Wednesday, September 11, 2013 8:57:50 AM
> Subject: Re: Disabling firewalld on AWS?
> 
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> On 09/11/2013 08:53 AM, Sam Kottler wrote:
> > 
> > 
> > ----- Original Message -----
> >> From: "Michael Hampton" <error at ioerror.us> To:
> >> cloud at lists.fedoraproject.org Sent: Wednesday, September 11, 2013
> >> 8:47:23 AM Subject: Re: Disabling firewalld on AWS?
> >> 
> >> 
> > On 09/11/2013 08:13 AM, Sam Kottler wrote:
> >>>> On 09/10/2013 11:36 PM, Sam Kottler wrote:
> >>>>>>>>> Given the deny-by-default nature of security groups I think
> >>>>>>>>>  it makes sense to disable firewalld in the AMI's. I
> >>>>>>>>> haven't seen any other AMI's that have a firewall enabled
> >>>>>>>>> by default and we probably shouldn't break that pattern
> >>>>>>>>> IMO.
> >>>>>>>>> 
> >>>>>>>>> Thoughts?
> >>>>>>>>> 
> >>>>>> 
> >>>>>> This is easily one of my least-favorite "features" of certain
> >>>>>> Linux distributions.
> >>>>>> 
> >>>>>> Debian/Ubuntu images don't have a firewall enabled by default in
> >>>>>>  their cloud images because they don't have a firewall enabled at
> >>>>>>  all in a default installation. At least the last time I looked
> >>>>>> at them; maybe they've gotten smarter in the last couple of
> >>>>>> years.
> >>>>>> 
> >>>>>> I'm not really sure I see a benefit here. There may not even be a
> >>>>>>  second firewall in front of the virtual machine; a user might
> >>>>>> turn it off because it's getting in the way, or a cloud provider
> >>>>>> might not provide this feature at all. I know of at least one
> >>>>>> public cloud provider which has an external firewall feature
> >>>>>> similar to AWS security groups, but it's off by default. In this
> >>>>>> case I see plenty of downside.
> >>>>>> 
> >>>>>>> If people disable their firewall then that's their prerogative,
> >>>>>>>  but it's confusing and non-standard to have a firewall
> >>>>>>> running on the instance and one running via the security
> >>>>>>> group(s) that the host is in.
> >>>>> 
> >>>>> Also, I don't trust the public cloud providers to configure their
> >>>>> firewall correctly.
> >>>> 
> >>>> So in your case you just `chkconfig firewalld on` and configure it.
> >>>> I'm sure that people who share your opinion (myself among them) will
> >>>> do that for the extra layer of security, but I'm just advocating for
> >>>> the Fedora images to follow the way other AMI's are handling
> >>>> firewalls.
> > 
> > And I'm saying that the way other AMIs do it is wrong. We should not also
> > be wrong merely because everyone else is jumping off the cliff. Rather we
> > should continue to be secure by default and require explicit action from
> > the user to disable security, not explicit action to enable security.
> > 
> >> It's not "disabl[ing] security", security groups already do that for
> >> you. You're adding an extra convoluted layer, and the vast majority of
> >> users will just disable it and rely on security groups (that's conjecture
> >> on my part). Have you ever heard about vulnerabilities in the AWS
> >> security group implementation? I haven't.
> > 
> I would figure Amazon would do everything in its power to prevent leakage of
> information about vulnerabilities to the public.  Their stock price would
> take
> a large hit...

Right, but I'm sure there are outside security researchers who are looking at security groups who would publicly disclose vulnerabilities. There have been vulnerabilities in iptables in the past and I'm sure there will be in the future, too.

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