/ip firewall filter
add action=drop chain=input comment="drop ssh brute forcers" dst-port=22 \
    protocol=tcp src-address-list=ssh_blacklist
add action=add-src-to-address-list address-list=ssh_blacklist \
    address-list-timeout=1w3d chain=input connection-state=new dst-port=22 \
    protocol=tcp src-address-list=ssh_stage3
add action=add-src-to-address-list address-list=ssh_stage3 \
    address-list-timeout=1m chain=input connection-state=new dst-port=22 \
    protocol=tcp src-address-list=ssh_stage2
add action=add-src-to-address-list address-list=ssh_stage2 \
    address-list-timeout=1m chain=input connection-state=new dst-port=22 \
    protocol=tcp src-address-list=ssh_stage1
add action=add-src-to-address-list address-list=ssh_stage1 \
    address-list-timeout=1m chain=input connection-state=new dst-port=22 \
    protocol=tcp
add action=drop chain=forward comment="drop ssh brute downstream" protocol=\
    tcp src-address-list=ssh_blacklist