The specific file vios-adventerprisek9-m.vmdk.spa.157-3.m3 is an image for the Cisco IOSv virtual platform, typically used in lab environments like GNS3 or CML (Cisco Modeling Labs). Important Note on Downloading
These images are proprietary and officially distributed as part of the Cisco Modeling Labs (CML) (formerly VIRL) software suite. Cross Platform Release Notes for Cisco IOS Release 15.7(3)M vios-adventerprisek9-m.vmdk.spa.157-3.m3 download
vios-adventerprisek9-m.vmdk.spa.157-3.m3 file.Final Recommendation: Visit software.cisco.com/download (requires a valid service contract) and search for "Cisco Modeling Labs Virtual IOS." Proceed from there. The specific file vios-adventerprisek9-m
k9 indicating that it includes full IPsec and other features typically requiring a strong encryption module. The -m could denote a specific packaging or feature set.