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Date:      Sun, 13 Apr 1997 17:48:54 +1000 (EST)
From:      "Daniel O'Callaghan" <danny@panda.hilink.com.au>
To:        Darren Reed <avalon@coombs.anu.edu.au>
Cc:        adam@veda.is, hackers@freebsd.org
Subject:   Re: kern/3244: ipfw flush closes connections
Message-ID:  <Pine.BSF.3.91.970413173618.10264z-100000@panda.hilink.com.au>
In-Reply-To: <199704120234.MAA07302@panda.hilink.com.au>

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On Sat, 12 Apr 1997, Darren Reed wrote:

> In some mail from Daniel O'Callaghan, sie said:
> > Have you read my earlier e-mail?  This occurs because if you leave out 
> > the '-q' option 'flush' says "Flushed all rules".  But when the tcp 
> > packets come to be sent, and error "Permission denied" is return, so 
> > telnetd/rlogind quite, kernel resets connection and the rest of 
> > rc.firewall is probably not executed.
> 
> Hmmm, if it returned EHOSTUNREACH, would that be as bad as EPERM ?

I don't know.  It couldn't be that hard to test, but I'm not really up 
with predicting kernel behaviour in my head.

A quick read indicates that ip_input() simply returns if its call to 
ip_fw_chk() returns -1, which is the case in a deny/reject.  Since rule 
65535 is a 'deny' rule, no ICMP is returned, as would be for 'reject'.

I'm not quite sure where the EPERM comes from - that's just the error you 
see if you do (at the console) 'ipfw -f flush; ping localhost'

Danny



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