The IKE daemon knows different numerical levels of logging, ranging from -1 to 4:
-1: Absolutely silent 0: Very basic auditing logs, (e.g. SA up/SA down) 1: Generic control flow with errors, a good default to see whats going on 2: More detailed debugging control flow 3: Including RAW data dumps in hex 4: Also include sensitive material in dumps, e.g. keys