Proof of Concept
Instead of using canned SSH-based probes for UNIX, we are researching the possibility of using SNMP against unix boxes (and possibly windows). In theory we can do this by simply replacing the SSH probes with equivalent SNMP probes which SNMP GET information from extended MIB objects which we apply to all machines we plan to instrument.
Since we have to touch all boxes anyway (even in "agentless" SSH probe mode), there is little or no opportunity cost to picking SNMP aside from the need to port the probes. But that cost is balanced by certain advantages:
- SNMP doesn't require us to open up shell access to a broad population of machines
- SNMP is the same protocol used for net devices & printers (2 down, Windows potentially remains the odd man out)
Linux
On Linux/net-snmp 5 here's one way to do extensions (there are several).
- Use "exec" to add an extension to snmpd.conf
exec echotest /bin/cat /etc/motd
- Restart snmpd and do a GET against a view which can see the extended MIBs
snmpget -v2c localhost -c public 'NET-SNMP-EXTEND-MIB::nsExtendOutputFull."echotest"'
...we may want to use SNMPv3, but the general idea is clear... we can expose arbitrary configuration data through SNMP. Since there are only a few dozen probes (and maybe only a subset of actual interest to Yale) we should be able to leverage SNMP for UNIX discovery instrumentation.