Newbie question, understanding of initial protocol running

[dcarped]

Hi to newbies and experienced users,

I've installed succesfully Cacti -v 0.8.7g on a Debian 64 bits distro.
As from the installation process, I get 4 graphs (memory usage, logged-in users, ...).
My question is quiet simple: What protocol lies these 4 graph on io to gather the data? Does it use net-snmp?
My intiution tells me that it not uses snmp. But is it this reflexion pertinent, what protocol than; icmp (I doubt not though)?
I've read and understood that on the server side you don't have to install snmp, snmpd will do. (on the agents snmp is required and only it. Basicaly remote stations need snmp, right?? The server whom cacti's running on needs snmpd )
why do I present this questions?
Following the installation of the packet mibs-downloader-snmp, I ran a /etc/init.d/snmp restart resolving in status snmpd not running (same status after a reboot). Therefore I assume the values being graphed aren't gathered using the net-snmp protocol. These 4 inital graphs are they able to get filled in while snmpd status tells me not running?

Thanks for your accurate know-how.
Dorian

[victorantunes]

Cacti can use several data gathering methods, since it works as a front end for RRDTool, which is kind of a universal data gathering/presentation tool.

SNMP is one of the possible methods for gathering data with Cacti, and possibly the most used one, since we're mostly talking about computer networks here. However, you'll also see a lot of custom scripts that run on PHP, Perl and etc.

To know precisely which methods a graph is using (and to better understand how Cacti works), I recommend you do a bit of investigating: go to Console -> Graph Templates and from there check its input items for which data sources they are using. From there, check said Data Sources to figure out which Data Templates they are using, and from those Data Templates you'll be able to tell how Cacti is getting data from the clients.

This link better expresses Cacti's functioning:
http://www.cacti.net/downloads/docs/htm ... iples.html

[cigamit]

Most of the default graphs for the local host are using perl scripts, not snmp.

[dcarped]

Hi

Thanks cigamit: You made me spare valuable time.

thanks victorantunes: I managed to settle/trace my path to the console window which showed the method used. This was in System utilities/View poller cache.
Refering to the link you provide:

To retrieve data from remote targets/hosts, cacti will mainly use the Simple Network Management Protocol SNMP

In the case the method of gathering on the localhost is based on a script, say in perl, if I want to monitor a remote host is it right that the same script is encapsulated in a SNMP packet io to poll the remote host? In other words, does a script work over a point to point/remote target and is capable to gather the data without usage of SNMP?

I need to open a new topic because I get *.rrd : No such file or directory following a graph creation.

Thanks for making out the understanding.

[cigamit]

No, to monitor a remote host, you generally need to use SNMP. This is completely different scripts / queries than the local perl scripts.

Its actually quite easy, just install an snmp agent on the remote host (net-snmp for linux or install the SNMP agent in Windows from the Add/Remove Components).

Then add the device to Cacti through the devices section, tell it to use SNMP v2, and input the Community String used on the remote host (by default, its "public")
After saving the device, it should show you up top if it was able to successfully contact the device via SNMP. Then begin by adding any the HOST MIB queries to the device (these are a few standard graphs that use SNMP), and it then should show you a listing of graphs you can create when you click the "Create Graphs" link.