Hi Roberto,
If you’re able to, please test the latest nightly. It contains a patch from Suricata which will enable cache management and reduce the amount of disk space used.
Thanks to @stevee for getting this updated hours after Suricata finished the patch. Not only was patching Suricata necessary but also a few other large packages too. The effort was not small. When the next version of Suricata is released this will likely include the patch, but as of now it is yet to be released.
So right now we are ahead of the game, which what you expect from IPFire, right? 
Since you’re connected via ssh you can stop IPS, delete its cache then restart IPS again:
/etc/rc.d/init.d/suricata stop
find /var/cache/suricata/ -type f -atime +7 -delete
/etc/rc.d/init.d/suricata start
This should free some space.
This might be the answer: Core 199 - Hostapd write exessives logs - #6 by ms
Thanks,
A G