Previous Table of Contents Next


Trace 7.1a. IP routing table retrieval (summary)

  Sniffer Network Analyzer data 5-Oct at 09:04:44, file NAME.ENC Pg 1
  SUMMARY  Delta T   Destination  Source    Summary
     9     0.0043    Agent        Manager   sNMP GetNext ipRouteDest..
                                           ipRouteIf Index
                                            (4 items)
    10      0.0102   Manager      Agent     SNMP GetReply ipRouteDest
                                           .. ipRouteIfIndex (4 items)
    11      0.0482   Agent        Manager   SNMP GetNext ipRouteDest
                                           .. ipRouteIfIndex (4 items)
    53      0.0662   Agent        Manager   SNMP GetNext ipRouteDest
                                           .. ipRouteIfIndex (4 items)
    54      0.0104   Manager      Agent     SNMP GetReply
                                           ipRouteDest .. ipRouteIfIndex
                                            (4 items)
    55      0.0687   Agent        Manager   SNMP GetNext ipRouteDest
                                           .. ipRouteIfIndex (4 items)
    56      0.0138   Manager      Agent     SNMP GetReply
                                           ipRouteIfIndex ..
                                            ipRouteMetric1
                                           (4 items)
    57      65.7201  HP133ADE     HP17B65F  ARP C PA=[128.79.3.105] PRO=IP
    58      0.0005   HP17B65F     HP133ADE  ARP R PA=[128.79.3.105]
                                           HA=080009133ADE PRO=IP
    59      82.5076  Agent        Manager   ICMP Echo
    60      0.0008   Manager      Agent     ICMP Echo reply
    61      50.1077  Agent        Manager   SNMP GetNext ifIndex
                                           .. ifPhysAddress (3 items)
    62      4.9924   Agent        Manager   SNMP GetNext ifIndex
                                           .. ifPhysAddress (3 items)
    63      5.0003   Agent        Manager   SNMP GetNext ifIndex
                                           .. ifPhysAddress (3 items)

Trace 7.1b. IP routing table retrieval details (GetNext Requests)

  Sniffer Network Analyzer data 5-Oct  at 09:04:44, file NAME.ENC
   Pg 1
  ------------------------- Frame 9 -----------------------------
  SNMP: ----- Simple Network Management Protocol (Version 1)-----
  SNMP:
  SNMP: Version = 0
  SNMP: Community = public
  SNMP: Command = Get next request
  SNMP: Request ID = 11386
  SNMP: Error status = 0 (No error)
  SNMP: Error index = 0
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.1} (ipRouteDest)
  SNMP: Value = NULL
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.7} (ipRouteNextHop)
  SNMP: Value = NULL
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.8} (ipRouteType)
  SNMP: Value = NULL
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.2} (ipRouteIfIndex)
  SNMP: Value = NULL
  SNMP:

  -------------------------- Frame 10 ---------------------------
  SNMP: ----- Simple Network Management Protocol (Version 1) ----
  SNMP:
  SNMP: Version = 0
  SNMP: Community = public
  SNMP: Command = Get response
  SNMP: Request ID = 11386
  SNMP: Error status = 0 (No error)
  SNMP: Error index = 0
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.1.0.0.0.0}
         (ipRouteDest.0.0.0.0)
  SNMP: Value = [0.0.0.0]
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.7.0.0.0.0}
         (ipRouteNextHop.0.0.0.0)
  SNMP: Value = [128.79.3.200]
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.8.0.0.0.0}
         (ipRouteType.0.0.0.0)
  SNMP: Value = 4 (indirect)
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.2.0.0.0.0}

         (ipRouteIfIndex.0.0.0.0)
  SNMP: Value = 2
  SNMP:

Trace 7.1c. IP routing table retrieval details (End of GetNext)

  Sniffer Network Analyzer data 5-Oct  at 09:04:44, file NAME.ENC
   Pg 1

  -------------------------- Frame 55 ---------------------------
  SNMP: ----- Simple Network Management Protocol (Version 1)-----
  SNMP:
  SNMP: Version = 0
  SNMP: Community = public
  SNMP: Command = Get next request
  SNMP: Request ID = 11409
  SNMP: Error status = 0 (No error)
  SNMP: Error index = 0
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.1.128.79.200.0}
            (ipRouteDest.128.79.200.0)
  SNMP: Value = NULL
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.7.128.79.200.0}
            (ipRouteNextHop.128.79.200.0)
  SNMP: Value = NULL
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.8.128.79.200.0}
            (ipRouteType.128.79.200.0)
  SNMP: Value = NULL
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.2.128.79.200.0}
            (ipRouteIfIndex.128.79.200.0)
  SNMP: Value = NULL
  SNMP:
  -------------------------- Frame 56 ---------------------------
  SNMP: ----- Simple Network Management Protocol (Version 1) ----
  SNMP:
  SNMP: Version = 0
  SNMP: Community = public
  SNMP: Command = Get response
  SNMP: Request ID = 11409
  SNMP: Error status = 0 (No error)
  SNMP: Error index = 0
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.2.0.0.0.0} (ipRouteIfIndex.0.0.0.0)
  SNMP: Value = 2
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.8.0.0.0.0} (ipRouteType.0.0.0.0)
  SNMP: Value = 4 (indirect)
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.9.0.0.0.0} (ipRouteProto.0.0.0.0)
  SNMP: Value = 2 (local)
  SNMP:
  SNMP: Object = {1.3.6.1.2.1.4.21.1.3.0.0.0.0} (ipRouteMetric1.0.0.0.0)
  SNMP: Value = 1
  SNMP:

7.2 Verifying Access Control with the Community Name and IP Address

Many network devices, such as routers, allow the network administrator to configure multiple SNMP community names for remote access. In addition, the network device can have a filter that specifies the IP address of the remote manager. Thus, the combination of the community name and the IP address acts as a two–level method of remote access security.

In this example, a router was configured with two SNMP communities (see Figure 7-2). The first uses community name = abcsnmp and allows access with IP address [XXX.YYY.ZZZ.145]. The second uses community name = xyzsnmp and allows access with IP address [XXX.YYY.ZZZ.146]. Let's see how the router reacts to an invalid request.


Figure 7-2  Agent access from multiple communities

In Frame 64 of Trace 7.2a, Manager 145 issues a GetRequest for the value of the sysDescr object. As you can see in Frame 64 of Trace 7.2b, that GetRequest includes the community name = abcsnmp. Since a match exists between the community name and the IP address, the router issues a GetResponse (Frame 65) containing the system description

     Value = /usr3/wf/wf.rel/v5.75/wf.pj/proto.ss/ace_test.p/


Previous Table of Contents Next