On Fri, 2013-09-13 at 20:46 +0000, Andy Cress wrote:
> Folks,
>
> Currently net-snmp measures sysUpTime relative to when the snmpd
> starts, and perhaps that is often the same as the overall system
> uptime, but in some systems, the services could be restarted without
> rebooting, so I am proposing that the sysUpTime should be measured
> against the /proc/uptime or /usr/bin/uptime value instead. The daemon
> could read this at init time.
I recently came across this problem on an embedded system where I was
restarting the daemon in the (extremely rare) event that I needed to
change an account password. Suddenly my "reboot" detection triggered
because sysUptime had gone backwards.
I could see various solutions to this problem:
1) Use the MIB based authentication configuration, but this wasn't an option
for me as we didn't want that enabled in the system.
2) Find some other way of re-configuring snmpd without restarting. Well
I failed on that one.
3) Find some other, more appropriate object to use for reboot detection.
Again I failed.
4) Patch snmpd to use the system uptime.
I ended up doing the latter, even though I don't believe it's strictly correct
(see patch below). I wonder if this could be put in inside #ifdefs for we
strange people who prefer the non-correct operation?
diff -Naur net-snmp-5.7.2_unpatched/agent/mibgroup/mibII/system_mib.c
net-snmp-5.7.2/agent/mibgroup/mibII/system_mib.c
--- net-snmp-5.7.2_unpatched/agent/mibgroup/mibII/system_mib.c 2013-08-13
16:10:04.653206559 +0100
+++ net-snmp-5.7.2/agent/mibgroup/mibII/system_mib.c 2013-08-13
16:14:57.789213501 +0100
@@ -231,7 +231,7 @@
netsnmp_request_info *requests)
{
snmp_set_var_typed_integer(requests->requestvb, ASN_TIMETICKS,
- netsnmp_get_agent_uptime());
+ get_uptime());
return SNMP_ERR_NOERROR;
}
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