speed match v0.1 options:
--pps/bps/Bps value Limit by value PacketPerSecond/BitsPerSecond/BytesPerSecond
--ip/sip/dip adderss Match ip/src/dst adderss
--mask netmask Netmask for ip adderss
--class id class id length
For limit 192.168.0.0/23 per C class for 20KBps.
iptables -A FORWARD -m speed --Bps 20k --ip 192.168.0.0 --mask 255.255.254.0 --class 24 -j DROP
or iptables -A FORWARD -m speed --Bps 20k --ip 192.168.0.0 --mask 23 --class 24 -j DROP