; ; SNMP in HotSaNIC ; With the 0.5 release of HotSaNIC the new SNMP enhancement was introduced. I will try to assamble all usefull information about the snmp part in this document to give the user an overview whats happening and help developers to make their own SNMP enhanced modules. -------- Overview -------- All mdoules gathering data through SNMP use the lib/HotSaNICsnmp.pm module to communicate with the SNMP server and collect the needed information. The module tries to guess the version of SNMP to use and the "kind" of interface (perl module Net::SNMP or system commands). After the first call by anyone module the guessed version is stored in a file to be read for later calls. Located in $HotSaNIC/modules and named $host.info. This is important to know, because if the server is down for some reason the content might be wrong, to be sure just do the following: 1. Stop HotSaNIC 2. Delete the file(s) storing version information 3. Start HotSaNIC Probing for each host is done again by the first module doing some SNMP query. Supported protocol versions are: SNMPv1 and SNMPv2c Probing is done by sending a get_bulk_request to the agent. If this request fails it is assumed that the agent runs protocol version 1 and this will be used for all further queries to the same address. ------------------------------------------------- Modules with SNMP support with sample config line ------------------------------------------------- apps: APP=SNMP:192.168.1.1:public:sshd,sshd@gateway part: DRIVE=SNMP:192.168.1.1:public:/dev/hda1,root-fs@gateway system: HOST=SNMP:192.168.1.1:public,Gateway traffic: DEV="SNMP:192.168.1.1:public:eth0,12500000,12500000,100MBit Ethernet" ------------------------- Sample run in the logfile ------------------------- To give you a clue about a correct run of SNMP query here is a log examples. To get all information you have to set the DEBUGLEVEL option in the main settings file to 5. The APPS module without preprobed version: starting module: "apps" Operating system "linux" not supported! Falling back to "default" .running on PID 14565 1053344545: main loop running 1053344545: signaling 14565 0.181(apps) 1053344545 APPS: enter snmp_walk() 1053344545 APPS: probe_version() module 1053344545 APPS: set_version() [2c] 1053344545 APPS: snmp_mod_walk() [HASH(0x82c4d6c)] 1053344545 APPS: leave snmp_walk() After normal startup the first query to the snmp daemon is done by calling snmp_walk which logs entry and exit point enclosing the whole process. After entering snmp_walk the set_version() function is called which needs to call probe_version(), the occurence of the logentries is a bit confusing because all function log at the end before returning. But well the set_version line shows us that the probed version is '2c' which is correct in this case and the snmp_mod_walk() function is called because of the presence of Net::SNMP it handles the request and returns a hash of results. If the module is not availible to the function it would have handed out the control to snmp_sys_walk(), which does the query by calling apropiate system commands. -------------------------- snmp_walk() and snmp_get() -------------------------- These two functions are the core of the HotSaNICsnmp.pm from the modules point of view. Their synopsis is: $res = snmp_walk($host, $community, @oids) $res = snmp_get($host, community, @oids) $res is in both cases a reference to a hash which contains the result in the form $res{$oid} = $value and the array argument @oids always contains a list of oids to query either with the (bulk)walk or the get mehtod. I hope I documented the HotSaNICsnmp.pm good enough to make clear whats going on, so if you want more details on the functions you might want to look in there. WebSVN - hotsanic - Blame - Rev 9 - /trunk/Documentation/README.snmp

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