Date: Thu, 21 Aug 2008 15:54:15 -0400 From: Mikhail Teterin <mi+mill@aldan.algebra.com> To: Neil Neely <neil@neely.cx> Cc: freebsd-security@freebsd.org, freebsd-stable@FreeBSD.org Subject: Re: machine hangs on occasion - correlated with ssh break-in attempts Message-ID: <48ADC7E7.9030907@aldan.algebra.com> In-Reply-To: <B9E94DF3-52B5-4A5E-9BDF-18773F34DF91@neely.cx> References: <48ADA81E.7090106@aldan.algebra.com> <B9E94DF3-52B5-4A5E-9BDF-18773F34DF91@neely.cx>
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Neil Neely ΞΑΠΙΣΑΧ(ΜΑ):
> I haven't explored this issue enough to speak with any authority - but
> once upon a time I had an app doing tons of ipfw rule add/removes all
> the time and we had no end of performance and stability problems on
> that box (this would have been in 4.x or so timeline I expect). As
> that approach wasn't really critical we abandoned it without really
> digging into the details.
>
> Years later a need for lots of rapid firewall changes came up again
> and I drilled into it and found the use of tables was excellent for
> doing this and it does the job very well. This is approach is on a
> FreeBSD 6.3 box.
>
> ipfw add 00550 deny ip from 'table(1)' to any
>
> Then just add remove entries to table 1 via:
> ipfw table 1 add 10.1.1.22/32
> ipfw table 1 delete 10.1.1.22/32
>
> show all entries in table 1 with:
> ipfw table 1 list
>
> Clear out the whole of table 1
> ipfw table 1 flush
>
> I can't be sure if this relates to your particular issue, but I would
> recommend trying it out.
Thanks! I was not even aware of this functionality... Yes, I'll try that
-- maybe, a bug in ipfw only hits once per 1000 invocations :-)
-mi
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