You're missing what version your running so I checked on my 1.3-AA, but it seems that those are not exist anymore...I only found below.
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# sysctl net.inet.ip.fw.curr_dyn_buckets=256
sysctl: unknown oid 'net.inet.ip.fw.curr_dyn_buckets'
# sysctl net.inet.ip.fw.dyn_buckets=2048
sysctl: unknown oid 'net.inet.ip.fw.dyn_buckets'
#
# sysctl -a|grep bucket
net.inet.tcp.hostcache.bucketlimit: 30
net.inet.tcp.syncache.bucketlimit: 30
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Are those still exist in 1.2* ? Then how about to put those into /boot/loader.conf, or very end of /etc/rc ??
cheers,