Networking / Beginners

Sender Policy Framework Overloading

Sender Policy Framework (SPF) is an example of a protocol that overloads existing DNS data types. SPF is an attempt to authenticate email and reduce undesirable email (spam). This protocol works by storing sender information in the TXT field. For example:

$ host -t txt abc.com
pobox.com descriptive text "v=spf1 mx mx:fallback-relay.%{d}
a:webmail.%{d} a:smtp.%{d} a:outgoing.smtp.%{d}
a:discard-reports.%{d} a:discards.%{d} mx:stor" "e.discard.%{d}
a:emerald.%{d} redirect=%{l1r+}._at_.%{o}._spf.%{d}"

The TXT field contains the SPF information. It specifies the authorized sources for email from the pobox.com domain.

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In this tutorial:

  1. Domain Name System (DNS)
  2. DNS Common Uses
  3. Hostname-to-Address Mapping
  4. Common Lookup Tools
  5. Naming Confusion Attack Vectors
  6. Dotted Names
  7. Name Formatting
  8. Exploited Anonymity
  9. Mail Servers
  10. Sender Policy Framework Overloading
  11. Domain Keys Overloading
  12. DNS Protocol
  13. Packet Information
  14. Simple DNS Server
  15. Distributed Architecture
  16. Top Level Domain Servers
  17. Generic Top Level Domain (gTLD)
  18. Secondary Level Domain (SLD)
  19. Primary and Secondary Servers
  20. Caching Servers
  21. DNS Management
  22. DNS Direct Risks
  23. DNS Performance versus Security
  24. DNS Cache Poisoning
  25. Corrupt DNS Packets
  26. DNS Domain Hijacking
  27. DNS Server Hijacking
  28. Dynamic DNS
  29. Similar Hostnames
  30. Domain Renewals
  31. Hostnames
  32. Zone Transfers
  33. Host Listing
  34. DNS Fields
  35. Mitgation Option
  36. Technical Threat Mitigation
  37. Social Threat Mitigation
  38. Defining Trusted Replies