DHCP leased workstations

[Sigy]

Hi everyone

First of all "Cacti is a great tool !! "

I have a network:
10.10.10.0/24
10.10.11.0/24
10.10.12.0/24
10.10.13.0/24

The workstations in this networks are DHCP-leased.

I need a script or tool in cacti who can monitor such devices when one of them go's offline.

I'm not familiar with scripting so is there someone who can help me with this isue ??

Thanks

[gandalf]

Sorry, I do not understand. What do you want to monitor from a workstation that is down? Od do you simply want to get an info about the fact, that it has gone down? EMail or the like? Did you have a look at the Device list? The status of each device is reported here; but updates are only made at each polling interval.
Or you may have a look at the "Advanced PING Template" in this section of the forum. This even tells you about the RTT and the loss% of the target.
HTH
Reinhard

[Sigy]

Hi lvm

What i mean is that i have in all networks workstations (Hand helds). This workstations are normaly 24/7 alive. This means that if one of them become a leased address due bi DHCP-Server they will hold this address for a long time. The problem is when someone turn it off and on again then it dosn't become the same Ip-address. It will become another one bi DHCP-server.
What i want is a situation that i can "monitor" the workstations even if they change their ip address. Normaly there is no problem with it when i have a static Ip address but in this case I'm confused how to "monitor" devices that will change theitr Ip address time bi time.

I'm sorry for probably mi bad English. I hope there is someone who can help me with this.

[gandalf]

Sorry,
personally I do not have a clue for that at the moment.
But is it an option to modify the dhcp lease time of that DHCP server? Then, the clients should regain their original IP address from DHCP server.
Reinhard

[egarnel]

what about usig dhcp reservations? Ip based monitoring will only be effective if the device being monitored can be uniquelly identified consistantly, in this case, by ip address. Dhcp reservations will allow you to bind the same ip address to the same mac address without having to manually config tcp/ip settings on the end device[s]. Cacti with thold can then alert you via email if a device goes down

[Sigy]

hi egarnel,

Thanx for your replay

Can you explain me more how to do this because I don't have opperational access to the DHCP-server. Also can you explain me how to arange the "ping sweep"scanning of this 4 networks to become them allerting in thold and monitor ?

[egarnel]

If you have no operational [administrative ] access to the dhcp server, the best you can hope for is to ask for it to be done for you by an admin.

Here is a script I wrote a while back that does a ping sweep. Please read the notes involved.
DISCLAIMER: I suck at coding, so use the script at your own risk.

Note: The script has the size of the scope hardcoded in it. Since you are the operator of the dhcp server, you may not know the exact size of the scope, which will give an inaccurate count of hosts used per scope.

At least it will give you an idea of how to implement a ping sweep.
Also, a ping sweep can be resource intensive and can bring a server to its' knees. I would definately not try a sweep of all 4 subnets at the same time.

Again, as was stated before in this thread, ip based monitoring is only good if the address is consistant. A ping sweep will only give you a general idea and may not give any indication if a particular host is up/down or other, especially if that host has a different ip address.