Re: [lwip-devel] Junk in SNMP responses

[Dirk Ziegelmeier]

Place a breakpoint in

ip_NetToMediaTable_get_cell_value_core()

and check whether the correct MAC is returned for you GW. If it is correct, please check wireshark if the response is comparable to the other entries. I guess it is only an snmpwalk problem that tries to figure out if the returned value is a "printable"/"visible" string or not.

Dirk

On Mon, Oct 22, 2018 at 1:57 PM Gisle Vanem <address@hidden> wrote:

While testing the lwIP-SNMP client or agent (correct term?), using
Net-SNMP's snmpwalk, I see some responses with "junk" like
this (in the lwIP host's ARP table):

   snmpwalk.exe -M mibs -m ALL -v2c -c public 10.0.0.23 RFC1213-MIB::atPhysAddress
   RFC1213-MIB::atPhysAddress.1.10.0.0.1 = STRING: "╪δù0ëí"
   RFC1213-MIB::atPhysAddress.1.10.0.0.10 = Hex-STRING: E0 3F 49 81 2E EA
   RFC1213-MIB::atPhysAddress.1.10.0.0.21 = Hex-STRING: 94 A1 A2 07 04 BB

and:
   snmpwalk.exe -M mibs -m ALL -v2c -c public 10.0.0.23 RFC1213-MIB::ipNetToMediaPhysAddress
   RFC1213-MIB::ipNetToMediaPhysAddress.1.10.0.0.1 = STRING: "╪δù0ëí"
   RFC1213-MIB::ipNetToMediaPhysAddress.1.10.0.0.10 = Hex-STRING: E0 3F 49 81 2E EA
   RFC1213-MIB::ipNetToMediaPhysAddress.1.10.0.0.21 = Hex-STRING: 94 A1 A2 07 04 BB

(the lwIP host is at 10.0.0.23).

I do not claim to understand SNMP. Why are there seemingly 2 types
of responses here? Maybe Net-SNMP is to blame here?

The 'E0-3F-49-81-2E-EA' and '94 A1 A2 07 04 BB' are the correct MAC-addresses
of machines connecting to the lwIP web-server. 10.0.0.1 is my default GW.


--
--gv

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