# Forum in English  > Internet security for beginners  > Microsoft Windows  >  Protocol Numbers

## SDA

(last updated 2008-02-27)

Registries included below:
- Assigned Internet Protocol Numbers

Registry Name: Assigned Internet Protocol Numbers
Reference: [RFC5237]
Registration Procedures: IESG Approval or Standards Action
Note: In the Internet Protocol version 4 (IPv4) [RFC791] there is a field
called "Protocol" to identify the next level protocol.  This is an 8
bit field.  In Internet Protocol version 6 (IPv6) [RFC1883], this field
is called the "Next Header" field.
http://www.iana.org/assignments/protocol-numbers

----------

