SNMP Notes

The first thing I would like to do if I were you is to disable authorization. Otherwise, you may see a warning like the following example demonstrates and no message will be printed even when traps come in (because they are dropped silently).

# snmptrapd -f -Lo -m all -Os
Warning: no access control information configured.
This receiver will *NOT* accept any incoming notifications.
NET-SNMP version 5.5

This because, starting with release 5.3, access control checks will be applied to incoming notifications.

To disable it, append the following line to /etc/snmp/snmptrapd.conf:

disableAuthorization yes

This is achieved by -M. For example:

snmptrapd -f -Lo -m all -Os -M +/abs/path/to/dir1:/abs/path/to/dir2

Add -d, i.e.

snmptrapd -f -Lo -m all -Os -d

This is useful when you don't have dependant MIB files since this way you can at least take a peek at the message received.

Replace -Os in previous examples with -OS to print MIB module id. Use -Of instead to print full oids on output. For more output format options, please refer to manual.

Though this is not part of snmptrapd, here it is anyway.

tshark -f "udp port 162" -c 2 -w snmp.pcap -i lo