Re: [Nagios-users] How to check Internet access and/or DNS?

2006-01-24 Thread Marc Haber
On Wed, Jan 25, 2006 at 04:34:34PM +1300, Steve Shipway wrote:
> So many different ways to do this.  We do it thusly.
> 
> 1) Set up a host for your border router.
> 2) Within this, sefine a number of http check services that try to collect
> web pages from popular internet sites ( google, microsoft, ibm...).  Disable
> notifications on them.
> 3) Use check_summary (from nagiosexchange.org) to define a service which is
> OK if any of the http check services are OK, and critical if they are all
> down.

That's a quite neat idea. I like that. Thanks!

Greetings
Marc

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RE: [Nagios-users] How to check Internet access and/or DNS?

2006-01-24 Thread Steve Shipway
So many different ways to do this.  We do it thusly.

1) Set up a host for your border router.
2) Within this, sefine a number of http check services that try to collect
web pages from popular internet sites ( google, microsoft, ibm...).  Disable
notifications on them.
3) Use check_summary (from nagiosexchange.org) to define a service which is
OK if any of the http check services are OK, and critical if they are all
down.

Now, the check_summary service will go critical if and only if *all* the
http checks are failing, which would indicate a loss of Internet
connectivity somewhere beyond your border router.  You can even add a final
check to ping a known IP address on the internet to this in case your
external DNS fails.

Steve




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Re: [Nagios-users] How to check Internet access and/or DNS?

2006-01-24 Thread Hugo van der Kooij
On Tue, 24 Jan 2006, Guy B. Purcell wrote:

>
> On Jan 23, 2006, at 23:56, Marc Haber wrote:
>
> > some services, most notably DNS, depend on the Internet to be
> > available. I'd like to express this in Nagios configuration. I'd
> > probably need to have a service "Internet" for that where my DNS
> > service definitions could depend on to avoid DNS being reported down
> > in case of an internet outage.
> >
> > Any idea how to do this elegantly? I don't find the idea of pinging my
> > ISP's router at the national Internet Exchange Point very appealing.
>
> Configure the "parents" field in the host definition for the host
> running the service you're checking across the Internet.  It's parent
> should be your boarder router.  You'll need to make a host def. for
> that router, as well as a service to check on it (use the "dummy"
> service for that).  With such a setup, there'll be no real periodic
> check of the router, but it will be ping'd if your across-the-
> Internet service fails, and you'll get just one notification (either
> router down or remote service unavailable).

There are propably a dozen ways or more to do this.

My internet link is a fake host which has the IP adres of my DSL router.
On it I have defined a check which will see if a tunnel is still active.
(This tunnel is an accurate indication of my connectivity.)

The IPv6 tunnel is similarly defined giving me some indication wether or
not internet is available.

On my to-do list is to write a passive check that will turn snmp traps for
these tunnels into host down and host up events that I can feed to nagios.

Hugo.

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Re: [Nagios-users] How to check Internet access and/or DNS?

2006-01-24 Thread Guy B. Purcell


On Jan 23, 2006, at 23:56, Marc Haber wrote:


some services, most notably DNS, depend on the Internet to be
available. I'd like to express this in Nagios configuration. I'd
probably need to have a service "Internet" for that where my DNS
service definitions could depend on to avoid DNS being reported down
in case of an internet outage.

Any idea how to do this elegantly? I don't find the idea of pinging my
ISP's router at the national Internet Exchange Point very appealing.


Configure the "parents" field in the host definition for the host  
running the service you're checking across the Internet.  It's parent  
should be your boarder router.  You'll need to make a host def. for  
that router, as well as a service to check on it (use the "dummy"  
service for that).  With such a setup, there'll be no real periodic  
check of the router, but it will be ping'd if your across-the- 
Internet service fails, and you'll get just one notification (either  
router down or remote service unavailable).



On a second thought, how do I check DNS? I mean, even with the
Internet down, my local DNS servers probably can correctly serve DNS
records for my local network which they're authoritative for. So, does
it make sense to check the DNS servers once for an external host (like
www.nagios.org) and once for an internal host, resulting in two
services being checked on the DNS server?

What do you do regarding DNS server checks?


Well, you check the DNS with the check_dns plug-in, of course ;^)   
Seriously, though, it depends on your infrastructure.  Generally  
speaking, I suggest that you use the plug-in to monitor all of _your_  
nameservers and just assume that the only reason for the DNS outside  
of your organization to be down is an outage of your network,  
absolving you from having to monitor the DNS at large.  You can  
monitor your Internet connection itself in many ways--paid service  
from the Internet, free from your home network, free from within your  
org. looking out (with lots of variation thereof).  Pick what suits  
you best.


-Guy




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Re: [Nagios-users] How to check Internet access and/or DNS?

2006-01-24 Thread Brian Scanlan
On 24/01/06, Marc Haber <[EMAIL PROTECTED]> wrote:
> On a second thought, how do I check DNS? I mean, even with the
> Internet down, my local DNS servers probably can correctly serve DNS
> records for my local network which they're authoritative for. So, does
> it make sense to check the DNS servers once for an external host (like
> www.nagios.org) and once for an internal host, resulting in two
> services being checked on the DNS server?

Just do checks for a few DNS entries - your ISP's website, your
externally hosted website, your internal website, nagios.org... If
most of these go down at the same time as your web check to
google.com, you know there's something bad happening  :)

Brian.


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[Nagios-users] How to check Internet access and/or DNS?

2006-01-23 Thread Marc Haber
Hi,

some services, most notably DNS, depend on the Internet to be
available. I'd like to express this in Nagios configuration. I'd
probably need to have a service "Internet" for that where my DNS
service definitions could depend on to avoid DNS being reported down
in case of an internet outage.

Any idea how to do this elegantly? I don't find the idea of pinging my
ISP's router at the national Internet Exchange Point very appealing.

On a second thought, how do I check DNS? I mean, even with the
Internet down, my local DNS servers probably can correctly serve DNS
records for my local network which they're authoritative for. So, does
it make sense to check the DNS servers once for an external host (like
www.nagios.org) and once for an internal host, resulting in two
services being checked on the DNS server?

What do you do regarding DNS server checks?

Greetings
Marc

-- 
-
Marc Haber | "I don't trust Computers. They | Mailadresse im Header
Mannheim, Germany  |  lose things."Winona Ryder | Fon: *49 621 72739834
Nordisch by Nature |  How to make an American Quilt | Fax: *49 621 72739835


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