If you don't have any username password, then the only way to recover the password for IDS-4215 is to reimage the device.
If you had service account username/password, you might have logged in as the service account, su to root, then enter "passwd (user)" to reset a user's password.
Assuming that you dont have any username/password, On a 4215 (and also on 4210, 4220, 4230, 4235 and 4250) you can connect to the serial console, reboot the sensor, then when the Grub menu appears, select "Cisco IDS Recovery", choice 1 on the Grub menu. When this process completes, all user data on the sensor is lost. The system is restored back to the default state, except that the network settings are remembered. All accounts are deleted except for the single administrative account "cisco", whose password is reset to "cisco".
You'll need system image file to perform this operation. You may download these from following links given that your CCO ID has sufficient privileges-
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...