It defines the type of security algorithm performed on SNMP packets. These are used in only SNMPv3. There are 3 security levels namely:

1. noAuthNoPriv:

This (no authentication, no privacy) security level uses community string for authentication and no encryption for privacy.

2. authNopriv: This security level (authentication, no privacy) uses HMAC with Md5 for authentication and no encryption is used for privacy.

3. authPriv: This security level (authentication, privacy) uses HMAC with Md5 or SHA for authentication and encryption uses DES-56 algorithm.