In any network which provides some sort of useful service (essentially, everything but the smallest home networks used only for Internet connectivity), someone has to keep everything running. This may be the one administrator (as in the case with my home development network) or a team of dedicated specialists. Even in my own home network, my email, file access capabilities, and this very web site, depend on billions of tiny components all working correctly.
To keep on top of network usage, health, and problems, it is essential to use some software solution to detect problems.
Monitoring Software Packages
My current choice is Nagios.
Out-of-Band Monitoring / Alerting
It's all well and good that I have Nagios running, but since I only have one fiber line coming in, a connectivity loss will wipe out all external problem alerting - both via email and via email-to-SMS on my cell phone. The solution to this problem is out-of-band monitoring or alerting, where problem alerts are sent via some channel other than normal Internet connectivity.
One possible solution is a plug-in to the Asterisk PBX which allows, with the use of a POTS (analog telephone) card, a system to dial-out on a landline and "speak" an alert to your cell phone or voicemail. While this is a novel solution, the fact that my POTS service actually comes in as VoIP on my FiOS fiber line precludes this from any usefulness.
The two remaining possibilities are:
- The same Asterisk-based setup as above, but using a cell phone rather than the POTS landlines
- Some way to use a cellular handset as an SMS gateway, thereby sending SMS messages directly over the cellular network with no ties to the landline system.