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CITA 440 Week 7

CITA 440 Week 7. SNMPv1 Message Frame Analysis. Reference Links. Ethernet Type II Frame Format IP Header Format UDP Header Format SNMPv1 Message Format. Sample SNMPv1 Get-Next-Request Message Frame (CRC checksum not included). 00 0d 56 9e f6 da 00 04 76 dd 76 db 08 00 45 00

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CITA 440 Week 7

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  1. CITA 440 Week 7 SNMPv1 Message Frame Analysis

  2. Reference Links • Ethernet Type II Frame Format • IP Header Format • UDP Header Format • SNMPv1 Message Format

  3. Sample SNMPv1 Get-Next-Request Message Frame(CRC checksum not included) 00 0d 56 9e f6 da 00 04 76 dd 76 db 08 00 45 00 00 43 05 e8 00 00 80 11 3c dd 89 25 72 cf 89 25 72 cb 04 59 00 a1 00 2f d0 73 30 25 02 01 00 04 06 70 75 62 6c 69 63 a1 18 02 01 03 02 01 00 02 01 00 30 0d 30 0b 06 07 2b 06 01 02 01 01 05 05 00

  4. Ethernet Header (14 octets) 00 0d 56 9e f6 da 00 04 76 dd 76 db 08 00 • 00 0d 56 9e f6 da -- destination MAC • 00 04 76 dd 76 db -- source MAC • 08 00 -- EtherType (IPv4)

  5. IP Header (20 octets) 45 00 00 43 05 e8 00 00 80 11 3c dd 89 25 72 cf 89 25 72 cb • 4 -- version • 5 -- IP header length in words • 00 -- type of service (routine, normal) • 00 43 -- total length (67 octets) • 05 e8 -- identification • 00 00 -- fragment (no) • 80 -- time to live (128) • 11 -- protocol (17, UDP) • 3c dd -- header checksum • 89 25 72 cf -- source IP (137.37.114.207) • 89 25 72 cb -- destination IP (137.37.114.203)

  6. UDP Header (8 octets) 04 59 00 a1 00 2f d0 73 • 04 59 -- source port (1113) • 00 a1 -- destination port (161) • 00 2f -- total length (47) • d0 73 -- header checksum

  7. SNMP Message (39 octets) 30 25 02 01 00 04 06 70 75 62 6c 69 63 a1 18 02 01 03 02 01 00 02 01 00 30 0d 30 0b 06 07 2b 06 01 02 01 01 05 05 00 • 30 -- T (Universal 16, SEQUENCE) • 25 -- L (37) • 02 01 00 04 06 70 75 62 6c 69 63 a1 18 02 01 03 02 01 00 02 01 00 30 0d 30 0b 06 07 2b 06 01 02 01 01 05 05 00 -- V • 02 01 00 -- version (TLV, Universal 2, INTEGER 0) • 04 06 70 75 62 6c 69 63 -- community (TLV, Universal 4, OCTET STRING "public")

  8. SNMP PDU (26 octets) a1 18 02 01 03 02 01 00 02 01 00 30 0d 30 0b 06 07 2b 06 01 02 01 01 05 05 00 • a1 -- T (Universal 16, SEQUENCE, Context-Specific 1, GetNextRequest) • 18 -- L (24) • 02 01 03 02 01 00 02 01 00 30 0d 30 0b 06 07 2b 06 01 02 01 01 05 05 00 -- V • 02 01 03 -- request-id (TLV, Universal 2, INTEGER 3) • 02 01 00 -- error-status (TLV, Universal 2, INTEGER 0, noError) • 02 01 00 -- error-index (TLV, Universal 2, INTEGER 0) • 30 0d 30 0b 06 07 2b 06 01 02 01 01 05 05 00 -- variable-bindings

  9. Variable-Bindings (15 octets) 30 0d 30 0b 06 07 2b 06 01 02 01 01 05 05 00 • 30 -- T (Universal 16, SEQUENCE OF) • 0d -- L (13) • 30 0b 06 07 2b 06 01 02 01 01 05 05 00 -- V • 30 -- T (Universal 16, SEQUENCE) • 0b -- L (11) • 06 07 2b 06 01 02 01 01 05 05 00 -- V • 06 07 2b 06 01 02 01 01 05 -- OID (TLV, Universal 6, 1.3.6.1.2.1.1.5, sysName in system group) • 05 00 -- value (TL, Universal 5, NULL)

  10. Sample SNMPv1 Get-Response Message Frame 00 04 76 dd 76 db 00 0d 56 9e f6 da 08 00 45 00 00 4b cc e0 00 00 80 11 75 dc 89 25 72 cb 89 25 72 cf 00 a1 04 59 00 37 db 84 30 2d 02 01 00 04 06 70 75 62 6c 69 63 a2 20 02 01 03 02 01 00 02 01 00 30 15 30 13 06 08 2b 06 01 02 01 01 05 00 04 07 4e 59 35 31 31 38 34

  11. Variable-Bindings (23 octets) 30 15 30 13 06 08 2b 06 01 02 01 01 05 00 04 07 4e 59 35 31 31 38 34 • 30 -- T (Universal 16, SEQUENCE OF) • 15 -- L (21) • 30 13 06 08 2b 06 01 02 01 01 05 00 04 07 4e 59 35 31 31 38 34 -- V • 30 -- T (Universal 16, SEQUENCE) • 13 -- L (19) • 06 08 2b 06 01 02 01 01 05 00 04 07 4e 59 35 31 31 38 34-- V • 06 08 2b 06 01 02 01 01 05 00 -- OID (TLV, Universal 6, 1.3.6.1.2.1.1.5.0, sysName scalar value in system group) • 04 07 4e 59 35 31 31 38 34-- value (TLV, Universal 4, OCTET STRING "NY51184")

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