net.inet.ip.portrange.randomized=1 hurts

Dmitry Pryanishnikov dmitry at atlantis.dp.ua
Wed Jun 2 09:28:53 PDT 2004


Hello!

On Wed, 2 Jun 2004, Barney Wolff wrote:
> Is the problem that the two systems have different ideas of MSL?

 I haven't changed default

net.inet.tcp.msl: 30000

on server. Note that on client side, connection never goes to TIME WAIT,
because during active FTP server side closes data connection (see RFC793,
figure 6), so it goes down-left on diagram from ESTAB state through TIME WAIT
state; but client side receives this first FIN and goes down-right on diagram
through CLOSE WAIT and LAST-ACK states. So MSL on client side is actually N/A
in this case. We have asymmetry here: client has already forgot about previous
usage of data port, but server must remember about it during 2*MSL according
to RFC793.

Sincerely, Dmitry
-- 
Atlantis ISP, System Administrator
e-mail:  dmitry at atlantis.dp.ua
nic-hdl: LYNX-RIPE


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