Exploration should include
- DNS Security Extension (DNSSEC)
- Secure Shell (SSH)
- Secure/Multipurpose Internet Mail Extension (S/MIME)
- Simple Network Management Protocol, version 3 (SNMPv3)
- Hypertext Transfer Protocol (HTTPS) over Secure Sockets Layer (SSL)/Transport Layer Security (TLS)
- IP Security (IPSec)
- authentication header (AH)
- encapsulating security payloads (ESP)
- tunnel/transport
- Secure Post Office Protocol (POP)
- Internet Message Access Protocol (IMAP).