Security :: How To Threshold Value For Failed SSH Comms Script

I was playing around with a script that seems to work relatively for my needs when SSH comms fail - AKA a user or someone attacking. This works. But, how would I add a threshold value? lets say if there are 3 entries, then perform add the IP to iptables as a rule.

Code:
#!/bin/sh
#
# FIREWALL SCRIPT
#
# March 1st, 2011
#
# Purpose:
# Add offending IP from failed SSH connections
# to the iptables (firewall) rules.
#
## Vars:
TIMETHRESHOLD="10" .....