Вопрос: DynDNS.com и mikrotik hex lite rb750r2 (ROS 6.30.2). какой скрипт взять, чтоб динамический IP-адрес прописывался на сервис при изменении?

Лучший ответ: насколько помню, эти скрипты постоянно писали во внутреннюю память файлы/логи? не проще ли использовать встроенный ip/cloud? при функционале "из коробки" флэш целее будет

Худший ответ: Решение найдено!!! Просто нужен был "правильный скрипт" в причины  и нюансы не стал вдаваться - работает и хорошо! Вот работающий, если кто столкнётся с проблемой :# Based on a script found on the Internet.Will add attribution if I find it.
# Changed 20150719 by Graeme Ruthven (graeme@kula.co.nz)
# Modified to:
# - update using authentication in URL as original method appeared to stop working.
#   This was about the time of the RouterOS 6.30 release, but may be unrelated.
# - Get the previous IP from the contents of the dyndns.txt file, as the global variable
#   doesn't appear to persist.
#
# Reference: https://help.dyn.com/remote-access-api/perform-update/

:local username "xxxx"
:local password "xxxx"
:local hostname "xxxx.dyndns.org"
:local emailAddress "xxxxx@gmail.com"

:local url "dummy"
:local previousIP

:global dyndnsForce

:set dyndnsForce false

:log info ("UpdateDynDNS starts.")

# print some debug info
#:log info ("UpdateDynDNS: username = $username")
#:log info ("UpdateDynDNS: password = $password")
#:log info ("UpdateDynDNS: hostname = $hostname")
#:log info ("UpdateDynDNS: previousIP = $previousIP")

# I have some doubt over the persistence of the global previousIP.
# This value should be stored in /dyndns.txt after the last update attempt,
# preceded by the status and a space.
# For status values see: https://help.dyn.com/remote-access-api/return-codes/

:if ([:len [/file find name=dyndns.txt]] > 0) do={
   :local ipfile [/file get dyndns.txt contents]
   :local ipstart ([find $ipfile " " -1] + 1)
   :local ipend [:len $ipfile]
   :set previousIP [:pick $ipfile $ipstart $ipend]
} else={
   :set previousIP "0.0.0.0"
}

# get the current IP address from the internet (in case of double-nat)
/tool fetch mode=http address="checkip.dyn.com" src-path="/" dst-path="/dyndns.checkip.html"
:delay 1
:local result [/file get dyndns.checkip.html contents]

# parse the current IP result
:local resultLen [:len $result]
:local startLoc [:find $result ": " -1]
:set startLoc ($startLoc + 2)
:local endLoc [:find $result "</body>" -1]
:local currentIP [:pick $result $startLoc $endLoc]

# Remove the # on next line to force an update every single time - useful for debugging,
# but you could end up getting blacklisted by DynDNS!

#:set dyndnsForce true

# Determine if dyndns update is needed
# more dyndns updater request details http://www.dyndns.com/developers/specs/syntax.html

:if (($currentIP != $previousIP) || ($dyndnsForce = true)) do={
   :log info ("Changing IP from $previousIP to $currentIP.")
   :set dyndnsForce false
   :set url "http://$username:$password@members.dyndns.org/nic/update?hostname=$hostname&myip=$currentIP&wildcard=no"
   /tool fetch url=$url mode=http dst-path="/dyndns.txt"
  
# Original code:
#   /tool fetch user=$username password=$password mode=http address="members.dyndns.org" \
#      src-path="nic/update?system=dyndns&hostname=$hostname&myip=$currentIP&wildcard=no" \
#      dst-path="/dyndns.txt"

   :delay 1

 #  :set previousIP $currentIP

   :local result [/file get dyndns.txt contents]
   :log info ("UpdateDynDNS: Dyndns update needed")
   :log info ("UpdateDynDNS: Dyndns Update Result: ".$result)

# email result:
   :local output "DynDNS Update Result: $result"
} else={
   :log info ("UpdateDynDNS: No dyndns update needed")
}
а вот ссылка:  forum.mikrotik.com/viewtopic.php?t=98426