How can I display current connections for designated IP, using /ip firewall connections. Is it possible at all? I would like to kill connections for one IP using script 
Thanks
You can deny an IP completely… if that’s what you mean.
open up winbox…
IP → Firewall
hit the + sign
change chain to FORWARD
src address to the address you want to block
change action to DROP
do the same steps except instead of forward, do INPUT (same host, src address)