[dba-Tech] Firewall alert - lsass.exe

I had a firewall alert today that I've never had before and I was hoping one
of you network gurus could shed some light on it for me. On W2k.
Here are the Details:
the user has chosen to "block" communications
Inbound UDP packet
Local address,service is <snipped>
Remote address,service is (219.234.228.245,isakmp(500))
Process name is "C:\WINNT\system32\lsass.exe"

Does lsass.exe have something to do with login security?

JB