Clearing hung CLOSE_WAIT TCP/IP connections on a FreeBSD server.

I am using proftpd on  a FreeBSD 4.0 server.  After I disconnect from the ftp server there are multiple TCP connections in the CLOSE_WAIT state when I run a netstat.

tcp4       0      0  mymachine.ftp           x.x.x.5.4964        CLOSE_WAIT
tcp4       0      0  mymachine.ftp           x.x.x.4.4956        CLOSE_WAIT

Here is what I have in the proftpd.conf file

TimeoutLogin                    120
TimeoutIdle                      300
TimeoutNoTransfer            600
TimeoutStalled                  900
TimeoutSession                 1000

I also run ipfw on this server and tried the following commands to get rid of these hung connections:
net.inet.ip.fw.dyn_ack_lifetime=400

Is there a way I can make these CLOSE_WAIT sessions expire quickly?
mvarsAsked:
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gheistConnect With a Mentor Commented:
This is normal behavior.
Use maxusers=512 if this hits any system limits (I doubt).

These parameters affect this aspect of network
net.inet.tcp.keepidle: 7200000
net.inet.tcp.keepintvl: 75000
net.inet.tcp.keepinit: 75000
net.inet.tcp.always_keepalive: 1

(times in slowhz, i.e. half-seconds)
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