问题
Given the following sample/simple snmpd.conf (Net-SNMP 5.7.2 on RHEL 7.4)
rwcommunity private 192.168.56.101
trapsess -Ci --clientaddr=192.168.56.128 -v 2c -c private 192.168.56.101:162
when starting a SNMP Daemon
snmpd -f -Lo -D -C -c data/snmpd_test.conf udp:192.168.56.128:161
We obtain ''Start Up'' InformRequest with IP source 192.56.168.1 instead of ...128 (WireShark snapshot below)
It is not surprising as the -D option allows us to output the debug information saying that
trace: netsnmp_config_process_memory_list(): read_config.c, 696: read_config:mem: processing memory: clientaddr 192.168.56.128 trace: run_config_handler(): read_config.c, 562: 9:read_config:parser: clientaddr handler not registered for this time
Web sources however say:
snmp.conf
...This value is also used by snmpd when generating notifications.
snmpd.conf
trapsess [SNMPCMD_ARGS] HOST provides a more generic mechanism for defining notification destinations. SNMPCMD_ARGS should be the command-line options required for an equivalent snmptrap (or snmpinform) command to send the desired notification
I read also some old threads like this one
- However this option is working well with snmptrap
snmptrap -D -Lo -Ci --clientaddr=192.168.56.128 -M+path_to_my_mibs -v 2c -c private 192.168.56.101:162 "" .1.3.6.1.4.1.a.b.c.d.e.f.0 i 0
- This option is also working when placed in snmp.conf ( mind there is no 'd' here ) and then it applies to snmpset and snmpget (and maybe other)
So my question is: Is it a documentation error, a bug, a misuse of the Net-SNMP stack ?
回答1:
After a long struggle I may have an answer and I write a short note as I just found a trick
It seems that clientaddr is not parsed correctly wherever in the snmpd.conf
(I tried not also inside the trapsess line)
But it seems to be a valid option in the command line of snmpd
like it was a valid option in the snmptrap command line. So I assumed it could be the same parsing mechanism for both.
a condition also is that the IP addres must be valid one
which means that
snmpd -f -Lo -D -C -c data/snmpd_test.conf --clientaddr=192.168.56.128 udp:192.168.56.128:161
seems to fully solve my problem.
I will perform more tests and if accurate format this answer a little bit better but it seems a good hint.
来源：https://stackoverflow.com/questions/53767608/snmpd-conf-clientaddr-not-working-for-sending-trap-inform-with-given-ip-source