Mikrotik script to detect WAN IP updates and call scripts if it changes.

update_wan_ip.rsc

:global wanInterface "wan1"
:global wanIP "$wanIP"

# Get the current IP on the interface
:local currentIPtemp [/ip address get [find interface="$wanInterface" disabled=no] address];

# IP without netmask
:local currentIP [:pick $currentIPtemp 0 ([:len $currentIPtemp]-3)];

:if ($currentIP != $wanIP) do={
    /log info "wan ip changed from $wanIP to $currentIP"
    :set wanIP $currentIP
    /system script run ddns_freedns
    /system script run hairpin_nat
}