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A consequence of this issue is that when an affected version of snmp is installed,
MMIS will report a monitored service as 'down' when it is 'running' if the process name contains a space.
Max Message size too small/large
snmp_max_msg_size
The primary tunable NMIS configuration setting for SNMP is snmp_max_msg_size, which controls how large a single SNMP packet may be.
This can be set as a system-wide default (in the System menu, under System Configuration), or as a per-host setting (in the Edit Node menu, under Advanced Options).
The default for snmp_max_msg_size is 1472 bytes, just below the 1500 byte packet limit for normal Ethernets. In LAN-only scenarios it is possible to increase this past 1500 bytes: this causes IP fragments and packet reassembly, but unless your LAN is saturated and starving for bandwidth fragmentation is not a problem. The benefit of a larger SNMP packet would be that the data to be collected fits into fewer packets.
To quickly adjust this setting you could run the following command using the node_admin.pl tool that ships with NMIS. The max_messagesize value of course can be increased or decreased as desired.
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/usr/local/nmis9/admin/node_admin.pl act=set node=nodename entry.configuration.max_messagesize=2800 |