For some reason, for a long while now net-snmp which the snmpd agent on OS X is based on has been broken in several aspects.
First: there is some wierd error that keeps coming up (sometimes) when you try and start snmpd:
nlist err: neither icmpstat nor _icmpstat found.
which I found the answer to fixing here.
Pretty simple, change this line in /System/Library/StartupItems/SNMP/SNMP from:
/usr/sbin/snmpd to /usr/sbin/snmpd -I -icmp
OK, that fixes that.
Second, I want to specify in the snmpd.conf file data for the “agentaddress”. I want to run snmpd on a different port and/or to restrict it to a backside interface.
so, every time I would put something like this into snmpd.conf:
agentaddress 16001
which is what the interactive snmpconf program put in there itself, I’d get this annoying error message in /var/log/snmpd.log
Error opening specified endpoint “16001”
Server Exiting with code 1
ugh.
I finally figured out how to make the stupid thing work. Don’t put the agentaddress specification into snmpd.conf; add it to the command that launches snmpd as it can be a command line option.
So finally to get snmpd on OS X to work:
/usr/sbin/snmpd -I -icmp
becomes:
/usr/sbin/snmpd -I -icmp 16001 or
/usr/sbin/snmpd -I -icmp 127.0.0.1:16001
So apparently the issue is somewhere in the code that picks up this information from the config file and not with snmpd in general.
Like I said: VERY annoying.
Update: John Welch of AFP548.com fame has a new article giving a primer on snmp and it’s use/setup in 10.5/Leopard Server. From what we’ve seen with Leopard Server, Apple has fixed some of the basic flaws in snmp. As in, you don’t have to do the nonsense above any longer.