[bittorrent] BT, Nats, and hackers at the door...
Olaf van der Spek
olafvdspek at gmail.com
Mon May 30 07:41:52 EDT 2005
On 5/30/05, Bill Cox <bill at viasic.com> wrote:
> On Mon, 2005-05-30 at 11:20 +0200, Olaf van der Spek wrote:
> > On 5/30/05, Bill Cox <bill at viasic.com> wrote:
> > > Hi, Olaf.
> > >
> > Why would hardware be harder to hack than software?
> Dedicated hardware has software installed and tested at the factory. We
> Linux hackers install a lot of software ourselves. Getting it exactly
> right isn't our job (for most of us). It is their job. It's what they
> That's why I buy LinkSys router/firewall/NATs, rather than using my
> server to do the job. I trust Cisco's solution more than the open-
> source solution that I could install and configure myself. Not that I'm
> worried about the open-source solution's quality, but I make too many
> mistakes to be trusted to install a firewall/router/NAT.
> I might put more effort into it. I took a quick look at SmoothWall at
> sf.net. What stateless firewall software would you suggest?
I'd suggest a stateful firewall. But I don't have much experience with
firewalls. I use Windows XP Internet Connection Sharing and Firewall.
On my Linux servers, I have iptables but without any rules, so it's
basically without firewall.
> > Would that guarantee the security of your p2p app?
> Not completely. You need the kernel to get involved to properly police
> an app. However, you could police the app's internet traffic, which is
> one of the scariest avenues for abuse.
But if you look for example at HTTP servers. Most exploits use
perfectly valid HTTP 'traffic', so what would such a traffic filter
> > > The kernel
> > > could restrict such access, and report attempted violations.
> > I think SELinux does things like this.
> > Additional restrictions (and kernel-level configuration) would indeed
> > be a good thing.
> Agreed. I just did some googling, and found setfacl and getfacl in
> Linux, which seem to exist as commands, but don't yet do anything in
> Fedora Core 3. These will give administrators the ability to assign
> various groups access to various files and directories. That may be
> enough to secure access to the disk and devices reasonably well on a per
> application basis. For example, BT could be a user executing the
> bittorrent application, and belong to eth0. Then, if the ethernet
> device had an "ACL" entry like group:eth0:rw, only eth0 group processes
> could use it. However, it seems like we're a long way off from having
> most applications install with solid user configurable restrictions.
That's more like user-based access while you need process-based access.
> > > It's possible that when IPv6 is well established, average mom will be
> > > buying a stateful router rather than a NAT, but I'm not so sure.
> > Why not?
> > You *will* need a router to connect multiple hosts to one internet line.
> The stateful part implies a more sophisticated router, and the average
Not more sophisticated than NAT.
> > > Dynamic IPs and NATs are two more levels to help protect the end-user
> > > from hackers, and I'm concerned that ISPs will keep them in place even
> > > with IPv6.
> modem account gave me an IP address for two months at a time, so I doubt
> that they were trying to conserve IP addresses by only handing them out
> when needed. I think it was dynamic only for security reasons, and so
What security? Your back door would 'only' work for two months?
> Another reason that ISPs may like dynamic IPs is that it makes it hard
> for home users to have servers. Servers at home are probably a major
Servers at home?
Are simply compromised desktops?
> source of spam and other internet PITAs. In fact, AOL wont accept mail
> from my mail server, because they detect that it comes from a home-based
> Bell South server (which makes my mail server close to useless).
> > The reason to close all ports by default is that most apps listen on
> > all interfaces by default while they should only be listening on
> > localhost.
> That's why I keep my Linux firewall on. If I can still ssh in, I can do
> anything else once I'm logged in.
Why didn't you configure your apps to bind to localhost instead of all
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