NOUSER

[Rick Stevens]

On Fri, 2007-09-14 at 07:43 +0200, Gregory Machin wrote:
> > If you must leave ssh open to the outside world, use a simple iptables
> > ruleset to limit attempts:
> >
> > # This rejects ssh attempts more than twice in 180 seconds...
> > # First, mark attempts as part of the "sshattack" group...
> > -A INPUT -p tcp --syn --dport 22 -m recent --name sshattack --set
> > # Optional: Include this line if you want to log these attacks...
> > -A INPUT -p tcp --syn --dport 22 -m recent --name sshattack --rcheck
> > --seconds 180 --hitcount 2 -j LOG --log-prefix "SSH REJECT: "
> > # Finally, reject the connection if more than one attempt is made in 180
> > seconds...
> > -A INPUT -p tcp --syn --dport 22 -m recent --name sshattack --rcheck
> > --seconds 180 --hitcount 2 -j REJECT --reject-with tcp-reset
> >
> > If more than one ssh attempt is made in 180 seconds (three minutes)
> > from a given IP address, this blocks that IP address for that duration.
> > You get one try.  If you fail, you must wait 3 minutes before you can
> > try again.
> >
> > Note that even a successful login is counted.  If you log in and
> > immediately log out, you still have to wait 3 minutes to get in again.
> >
> > Change the "--hitcount 2" bits to "--hitcount 3" if you want to give
> > yourself two tries to get in.  You can also change the "--seconds 180"
> > to "--seconds 300" to make the delay 5 minutes.  The values I give above
> > are enough to discourage most script kiddie attempts to get into your
> > box.
> 
> Hi
> Sorry to hijack this tread. The above should it be before, or after
> you allow the ssh port ?

Before.  You want packets NOT rejected by that bit to fall through to
other rules for further processing.

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- Rick Stevens, Principal Engineer             rstevens at internap.com -
- CDN Systems, Internap, Inc.                http://www.internap.com -
-                                                                    -
-        Change is inevitable, except from a vending machine.        -
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