Exponential back off on failed logins
I'm trying to implement an exponential back off to thwart dictionary attacks. I'm currently being hit by over 5,000+ unique IPs, so linear rate limiting is not an effective solution.
Using the algorithm below, where 'T' is seconds before they can attempt another login and 'c' is the number of failed attempts.
T(c) = (2^c -1) / 2
I'm comfortable with general iRule aspects but tying in time with subtables is throwing me for a loop. If anyone wants to give it a crack, for simplicity write an exponential back off for any POST request.