1. DNS
    2. UDP
    3. SMTP
    4. POP
    5. PAP
    6. CHAP
    7. LDAP
    8. ICMP
    9. DHCP
    10. EAP
    11. 802.*
    12. RIP
    13. BGF
    14. OCSP

    RADIUS

    Remote Authentication Dial In User Service.

    1. https://en.wikipedia.org/wiki/RADIUS
    2. https://www.untruth.org/~josh/security/radius/radius-auth.html

    RADIUS is supported and used by almost all vendors of authentication devices and is de-facto standard protocol for remote authentication.

    IPv4

    Internet Protocol version 4.

    1. https://en.wikipedia.org/wiki/IPv4
    Offsets Octet 0 1 2 3
    Octet Bit 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
    0 0 Version IHL DSCP ECN Total Length
    4 32 Identification Flags Fragment Offset
    8 64 Time To Live Protocol Header Checksum
    12 96 Source IP Address
    16 128 Destination IP Address
    20 160 Options (if IHL > 5)
    ⋮ ⋮
    56 448

    UDP

    User Datagram Protocol.

    1. https://en.wikipedia.org/wiki/User_Datagram_Protocol
    Offsets Octet 0 1 2 3
    Octet Bit 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
    0 0 Source port Destination port
    4 32 Length Checksum

    TCP

    Transmission Control Protocol.

    1. https://en.wikipedia.org/wiki/Transmission_Control_Protocol
    Offsets Octet 0 1 2 3
    Octet Bit 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
    0 0 Source port Destination port
    4 32 Sequence number
    8 64 Acknowledgment number (if ACK set)
    12 96 Data offset Reserved
    0 0 0
    NS
    CWR
    ECE
    URG
    ACK
    PSH
    RST
    SYN
    FIN
    		Window Size
    16 128 Checksum Urgent pointer (if URG set)
    20
    		 160
    		 Options (if data offset > 5. Padded at the end with "0" bits if necessary.)
    ⋮ ⋮
    60 480

    Ethernet frame

    https://en.wikipedia.org/wiki/Ethernet_frame

    802.3 Ethernet packet and frame structure
    Layer Preamble Start frame delimiter MAC destination MAC source 802.1Q tag (optional) Ethertype (Ethernet II) or length (IEEE 802.3) Payload Frame check sequence (32‑bit CRC) Interpacket gap
    7 octets 1 octet 6 octets 6 octets (4 octets) 2 octets 46-1500 octets 4 octets 12 octets
    Layer 2 Ethernet frame ← 64–1522 octets →
    Layer 1 Ethernet packet & IPG ← 72–1530 octets → ← 12 octets →