SNAT and Forwarding (IP) virtual servers

iRule seem to be the best option... and works as expected. I'm still trying to find a way of keeping the information on the original source adresses. Following iRule would do the job, but it's not working (on a LTM v10.2.4) :

when LB_SELECTED {

if {[IP::addr "[IP::client_addr]/24" equals "[LB::server addr]/24"]} {

set osaddr IP::client_addr

scan $osaddr %d.%d.%d.%d ip1 ip2 ip3 ip4

set tsaddr 192.168.10.$ip4

snat $tsaddr

}

}

Any idea how to achive that ?

NB : I also tried to split the original source address with:

set ip4 [lindex [split $ip "."] 3]