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Date:      Sat, 29 Dec 2001 13:10:39 -0800
From:      "Crist J . Clark" <cjc@FreeBSD.ORG>
To:        Eugene Grosbein <eugen@www.svzserv.kemerovo.su>
Cc:        questions@FreeBSD.ORG
Subject:   Re: strange behavour of stock ftpd in STABLE: ports exhausion?
Message-ID:  <20011229131039.J93411@blossom.cjclark.org>
In-Reply-To: <20011229170326.A98378@svzserv.kemerovo.su>; from eugen@www.svzserv.kemerovo.su on Sat, Dec 29, 2001 at 05:03:26PM %2B0700
References:  <20011229170326.A98378@svzserv.kemerovo.su>

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On Sat, Dec 29, 2001 at 05:03:26PM +0700, Eugene Grosbein wrote:

This is not really a topic for -stable. Diverted to -questions.

> I use standard ftpd coming with FreeBSD 4.4-STABLE.
> 
> My /etc/sysctl.conf contain these lines:
> 
> net.inet.ip.portrange.hifirst=49152
> net.inet.ip.portrange.hilast=49200
> 
> This should restrict number of concurrent passive mode connections to 49.

Why would it?

> But this does much more. Suppose, a ftp client has good link to server,
> 100Mb ethernet in my case. Suppose it uses passive mode and starts
> to download very bug number of files sequentially, one then next then next...
> It says TYPE I, PASV, RETR, TYPE I, PASV, RETR...
> So, it can download 49 files in a row then server says 
> 425 Can't open passive connection: can't assign requested address

I don't see why it would say that, but anyway...

> If client does not break control connection, waits a little and
> starts to download the rest of files, it can download next 49 files and so on.
> 
> There are no other clients connected meantime.
> How can this happed?

Well... why wouldn't it? You get the 'can't assign requested address'
error when you try to open a connection on top of an existing one. If
the new TCP connection isn't trying to use an existing <source
address, source port, destination address, destination port> quartet
(notice that the client changes the source port too), it should work
fine. 
-- 
"It's always funny until someone gets hurt. Then it's hilarious."

Crist J. Clark                     |     cjclark@alum.mit.edu
                                   |     cjclark@jhu.edu
http://people.freebsd.org/~cjc/    |     cjc@freebsd.org

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