Change file crontab

[m4rk]

Hello,
I found this problem on Pfsense (version 10.3-REALEASE-p19):
I simply have to execute the file /etc/rc.dyndns.update every 2-3 minutes so i thougt to change the file /etc/crontab and infact when i saved the changes it worked. But when i do a restart of Pfsense the crontab file returnes in the default settings so i lost the changes. I have tried to change the file config.xml too, setting the minutes at 1 but nothing changed. Someboby can help me?
Thanks a lot

Marco

[doktornotor]

Install the cron package.