Kerlink iFemtocell - connect to TTN?

Hi @cpaumelle @Eelviny @kersing @Tord @disk91
I have problems connecting iFemtoCell-evolution” gateway to TTN, I did Keros 4.3.3: (CPF) configuration as it is written in Kerlink website, and my firmware version is Keros 4.3.3. (Starting v4.3.0, packet forwarder is included in the firmware)
I would appreciate if someone could advise me regarding these questions:

1) as there is no /user/spf/bin/execute_spf.sh file used in this version, which file I should open to edit the IPTable by replacing all “-A” (append) options by a “-I” (insert) for Keros 4.3.3 to connect TTN?

2) For the future usage and connecting it to ChirpStack, if after changing this rule to -I , I do a factory reset and upgrade with liveburner IPK, will these changes I made revert back to the default?