DOS prevention

[Andrew Beals]

It his pipe is full, then he has bigger problems than that which J. Random
Unix Jock can explain over a mass e-mail.  Especially when yum knows not of
fail2ban.

Serving 404 pages to script kiddies shouldn't Bork a server. It shouldn't
even put an appreciable load on it. Script kiddies are here to stay, thanks
to the fringe members of the "information should be free" crowd.  (Just as
an example, there appear to be about 1.6k copies of The Anarchist Cookbook
out there, ready for downloading.)

Andy
Ps. There are too many kittens - please spay/neuter your pets.

Any typos are the direct result of Swiftkey X's autocorrect function.
On Mar 18, 2013 2:40 PM, "Billy Crook" <billycrook at gmail.com> wrote:

> Every time you use a route table as a firewall, God kills a kitten.
>
> If you want a firewall, use..... a firewall.  iptables is the command.
>
> If you want something that scales, and won't require your time to
> maintain a shitlist of IPs; use fail2ban, and it will manage the list
> per your specifications.
>
> Most likely, your DoS is apache-local.  i.e. they aren't actually
> flooding your entire pipe.  If you use fail2ban/iptables, this should
> fix you right up.
>
> If they are flooding your actual pipe, you need to apply the filter on
> the far end of your pipe.  i.e. Get your ISP (or a new isp) that will
> let you administer an ACL on the router on THEIR side of your line.
> Or get a DDoS prevention service.  Blocking on the sonic wall will
> have NO affect on a flood if the sonic wall is at the same site as the
> targeted server.
>
> Fail2ban can integrate with this remote filtering too.  You simply
> modify fail2ban's 'action' to call a script that adds the IP upstream.
>
> On Mon, Mar 18, 2013 at 2:27 PM, Andrew Beals <andrew.beals at gmail.com>
> wrote:
> > If they're coming from just the single IP, then black-hole'ing their IP
> is
> > easier.  If the address they're coming from is 128.115.1.1, then simply
> > paste this at a shell prompt and give it your password when sudo asks for
> > it:
> >
> > sudo route add 128.115.1.1 gw 127.0.0.1 lo
> >
> > This will cause all packets destined to go back to them to get dropped on
> > the floor and should be sufficient.  You'd really prefer to do this (or
> just
> > add them to the naughty list which is something that I believe the SW can
> > do, even with ancient builds of their SW) on your SonicWall box, but you
> can
> > get away with doing it on your server.
> >
> > Adding an IP tables (again, if you can't convince your SW to just drop
> > packets from them) is more efficient, of course, but it's hairier to set
> up.
> >
> >
> >
> > On Mon, Mar 18, 2013 at 2:19 PM, J. Wade Michaelis
> > <jwade at userfriendlytech.net> wrote:
> >>
> >> I have a CentOS web server that has recently been brought to a halt on
> two
> >> separate occasions.  Checking the access.log, it appears that it was a
> >> Denial of Service (DOS) attack (hundreds of HTTP requests in a very
> short
> >> time, all from a single IP address).
> >>
> >> I want to prevent these types of attacks from bringing the server to its
> >> knees.  We have a hardware firewall (SonicWall) in place, but it isn't
> quite
> >> new enough to run the firmware that allows rate-limiting.
> >>
> >> I have found a number of tutorials that show how to do this type of
> thing
> >> with IPTABLES.  Is there a better solution?
> >>
> >> Supposing I go with IPTABLES, do I need to include rules to allow FTP
> and
> >> SSH (the only other services on the server)?
> >>
> >> Would any of you be willing to assist me with this?
> >>
> >> Thanks,
> >> ~ j.
> >> jwade at userfriendlytech.net
> >>
> >> _______________________________________________
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> >> KCLUG at kclug.org
> >> http://kclug.org/mailman/listinfo/kclug
> >
> >
> >
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>
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