A while back, I looked at a network monitoring product from Belkin called the Pulse, a stand alone hardware device for monitoring network components. Belkin discontinued the Pulse, but the product remains available in both hardware and virtual machine versions from the creator of the technology, Jumpnode.
Here, I'm going to look at a software based network monitoring product called Servers Alive from a company called Woodstone. I'm going to focus on the free version of Servers Alive, which is a limited 10 device version of their full blown products that can monitor up to 1000 devices (Standard Version = $279) or 5000 devices (Enterprise Version=$419).
I've been using Servers Alive on my network to monitor various different components, and have found it handy for detecting and notifying me of issues on my network. I'm using it to monitor the status of various devices, as well as some more advanced monitoring, including logging into the web utility of several devices and receiving SNMP traps.
To start, I downloaded and ran the 16.3MB salive.exe (v6.1) file on a Windows XP Pro PC, a process that took just a couple minutes. With the software installed, putting it to work is a matter of adding devices to the Start screen, shown in Figure 1 below, and choosing how they will be monitored.
Figure 1: Servers Alive Start Screen
Monitoring choices I use include running ping tests, checking disk space on network drives, logging into device web utilities, as well as receiving SNMP traps. There are additional tools for Protocol, NT Server and Database checks that can also be used.
The most basic network test is to ping the IP address of a device. Getting a response indicates the target device is powered on and running its basic network functionality.
To monitor my Asterisk PBX, I selected Add, entered the IP address of the device in the General Tab, then selected Ping under the Check Tab, as shown in Figure 2. Servers Alive now pings my VoIP PBX 5 times every 3 minutes and will generate an alert if the device fails to respond 2 or more times per 5 pings.
Figure 2: Checking via ping
In addition to my ATA, I monitor my VoIP ATA and a WIFI Access Point with ping checks. Since the WIFI Access Point I'm pinging is only reachable through a VPN connection, I'm effectively monitoring the status of the VPN link with this same test.
NAS Free Space
With several NAS devices on my network, Servers Alive provides a useful means of checking their up/down status and their disk utilization. By entering the network path to the file share, Servers Alive can report the amount of remaining disk space on a share, as well as alarm if the amount of disk space falls below a specified threshold.
In Figure 3, I've configured Servers Alive to monitor a NAS device on my LAN at \\192.168.3.170\share. Notice how it is set to alarm if remaining disk space drops to less than 10 GB.
Figure 3: Monitoring NAS free space
Another useful test is to configure Servers Alive to log into the web utility of a device. This not only verifies the device is on line, it also verifies the device's software is running.
In Figure 4, I've configured Servers Alive to log into my WIFI router's web page, by selecting URL as my network Check, entering the IP address of the device, clicking Password protected page, and entering the user name and password to allow Servers Alive to log in.
Figure 4: Checking a router's login
Servers Alive can monitor web servers via public IP addresses or URLs. In addition to logging in to my WIFI router on my LAN, I was able to input a Dynamic DNS domain name in the server name and Check field to have Servers Alive monitor a network device external to my LAN.