Security Protocols

Security Protocols - Web

  • SSL - Secure Sockets Layer (latest version: 3.0) {source}
    • Now depreciated by the IETF and should not be used.
    • Uses certificates for authentication and encryption for message integrity and confidentiality.
    • Establishes a stateful connection.
  • TLS - Transport Layer Security {source}
    • Based on SSL v3.0
    • Provides privacy (symmetric encryption), message integrity (Message Authentication Code), and authentication (PKI digital certificates).
    • Forward secrecy ensuring that any future disclosure of encryption keys cannot be used to decrypt any TLS communications recorded in the past.
    • Uses SSL/TLS to secure web-based communications.
    • X.509 digital certificates.
    • 256-bit encryption keys.

Domain Name Service (DNS) Security

  • Suite of Internet Engineering Task Force (IETF) specifications.
  • Protects against DNS Cache Poisoning.
  • DNS extensions provide DNS clients (resolvers) origin authentication of the DNS data, authenticated denail of existence, and data integrity.
    • Not confidentiality or availability.

SSH - Secure Shell {source}

  • Replaces telnet for remote communications.
  • Establishes a session between the client and host computers using an authenticated and encrypted connection.
  • Uses the asymmetric (public key) RSA cryptography for both connection and authentication.
  • Used for remote administration of Linux servers.
  • Other protocols can tunnel through SSH.

Secure Email

  • Secure / Multipurpose Internet Mail Exentioins (S/MIME)
    • A standard for encryption (confidentiality) and signing (authentication) of MIME (email) data.
    • Requires PKI and uses Certificate Authorities (CA).
    • Internal Email.
  • POP3S and IMAPS
    • Use SSL to secure emails in transit between a POP or an IMAP server and the client.
    • External email.

FTPS - Securing FTP

  • FTP - File Transfer Protocol
    • Passes credentials in clear text.
  • FTPS - FTP extension that adds SSL/TLS
    • Mutual authentication of parties (certificates).
    • Data confidentiality (encryption) and integrity (hashing).
    • FTPS Implicit over port 990.
    • FTPS Explicit over port 21.
  • SFTP (Secure FTP)
    • Uses SSH to transfer files (SSL encapsulation).


  • Secure voice and video transmissions.
  • Voice and video calls are established with session initiation protocol (SIP) and data is transmitted with realtime transfer protocol (RTP).
  • The Secure Real-Time Transport Protocol (SRTP)
    • Extension to RTP.
    • Intended to provide encryption, message authentication and integrity, and replay attack protection to the RTP data in both unicast and multicast applications.


  • LDAP is a Directory Protocol
    • Contains sensitive information about organizational systems and users.
  • Attackers may sniff the network to read unencrypted LDAP traffic.
  • LDAPS over SSL/TLS
  • Uses TCP port 636.


  • SNMP (Simple Network Management Protocol) used to manage networks.
  • Each managed device has a software agent reporting configuration settings and alerts (traps) to a central SNMP Management Server.
  • SNMPv1 & v2 sent all data as clear text.
  • SNMPv3 encrypts data.
  • Uses port 161.

Network Address Allocation

  • Allocating IP addresses.
  • DHCP (Dynamic Host Control Protocol) - Assigns internal IP addresses.
  • Use of network subnets to segregate multiple hosts and control network traffic.

Time Synchronization

  • NTP (Network Time Protocol) - UDP protocol used to synch time based on the atomic clock.
  • NTP Servers - redundant and secured.

Subscription Services

  • Software as a Service (SaaS)
  • Cloud email: Gmail, microsoft office, etc.
  • Network defenses:
    • Firewall / IDS/IPS
    • Web and app filtering.
    • AV
    • Patching

Secure Copy Protocol (SCP) {source}

  • A means of securely trasnferring files between a local host and a remote host or between two remote hosts.
  • Based on SSH.
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On this page
Security Protocols - Web
Domain Name Service (DNS) Security
SSH - Secure Shell {source}
Secure Email
FTPS - Securing FTP
Network Address Allocation
Time Synchronization
Subscription Services
Secure Copy Protocol (SCP) {source}