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Our internet connection is awful. It goes up and down several times during the day without warning. Every time it does, we get a large number of calls saying the network is down.

Replacing the internet connection isn't an option because they're the only one that services the building we're in.

I was wondering if anyone knew a way to notify everyone automatically when our ISP goes down. Ideally it would be an internal website users can visit to see if the ISP is down (e.g. visit http://isbroadstripedown and see what the current status is) but if it's an internal program we run on a server or workstation that'll work too. Just as long as people can visit it to see what's going on.

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Which operating system would you prefer to use in general, and which one are you using on your gateway? –  Eduardo Ivanec Apr 15 '11 at 18:21
Windows 2008 (I know, I know) and a Juniper SSG 5 as the gateway. –  zippy Apr 15 '11 at 18:30
We ended up going with a Ruby on Rails webapp that pings our static IP address and the ISP gateway address every minute. I'll give the answer to Alex for Nagios which is probably the "correct" solution. –  zippy Apr 22 '11 at 3:22
carrier pigeon and smoke signals. ;-) sorry! –  Tom H Jan 31 '12 at 22:35
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5 Answers

up vote 4 down vote accepted

Install Nagios, do a check-host-alive on Google.com or your ISP gateway.

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Sledgehammer, meet nut. –  Izzy Apr 15 '11 at 18:17
I've used nagios many times before, and you can set it to send mass-emails out when the gateway goes down, or throwing a "net send" message using the windows messaging system. I would still argue that fixing the connectivity issues is much easier than deploying nagios & annoying people with mass notices that the internet is down. –  TheCompWiz Apr 15 '11 at 18:30
I agree completely about fixing the problem at the root, but they are literally the only ISP who services the building. It's that bad. –  zippy Apr 15 '11 at 18:33
Perhaps the problem(s) can be resolved at the demarc... More info on the problem in a new SO post would be a good start... –  TheCompWiz Apr 15 '11 at 18:40
+1 for nagios. If you think it's too powerful, you can write a cronjob or daemon that will ping google or something and send out a mass email if it goes down. –  pfyon Apr 15 '11 at 19:02
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Back in college, we would use Vocalnet to broadcast such alerts. The investigator would stick his/her head out of the office door and shout "HEY EVERYBODY, THE INTERNET IS DOWN!" into the hallway.

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Ok... that made me LOL. Bit un-professional... but still funny. It's still 1 better than TCP over carrier pidgins. ietf.org/rfc/rfc1149.txt –  TheCompWiz Apr 15 '11 at 18:27
Maybe you could hook up a siren and a warning light so that it turns on when your pings fail, then turns off when the internet is working. I know one thing for sure, it will stop people calling you, and eventually they'll be grateful when the whole system goes away and won't bother you again to let you know about what you already know. –  Ernie Apr 15 '11 at 18:45
Unfortunately this isn't a real solution for me so I can't give you credit for the answer. –  zippy Apr 19 '11 at 18:29
zippy, I just wanted to earn enough rep on serverfault to vote up somebody elses answer to a different question, so I went looking to see if there was a question I could answer. there wasn't. ergo, the vocalnet jibe. the funny thing is that my rep jumped to 75 within an hour of posting that. over on stackoverflow, I put in a meticulous answer to a question with code sample and screenshot to facilitate the reader's understanding. my rep over there is only hovering at around 35 after 3 weeks. so it goes. –  randomfactor Apr 21 '11 at 18:03
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I don't know Juniper, but if it has support for DNAT or redirects you could perhaps set up a rule to activate on demand that redirects all http traffic to an information page that tells users that service is down (sort of a transparent proxy). This works better if most of the people use HTTP over all things.

You can do this more easily if you already have a proxy in place for internet access, of course.

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In the older versions of Windows, you could send messages to workstations that would be presented as popups on screens, using "net send". There seem to be a similar mechanism (msg.exe) in modern versions. Similar things can probably be achieved with a small daemon and an OSD library on Linux boxen.

You could trigger such a message from e.g. Nagios, but just triggering it by hand will probably be enough.

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Do you have an internally hosted email?

If you do, you can blast out an email to ALL@youroffice.com with an ETA if one exists.

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Nope...it's an externally hosted email provider. –  zippy Apr 19 '11 at 18:31
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